PHYSICAL REVIEW D 99, 035046 (2019)
Partially composite supersymmetry
† ‡ Yusuf Buyukdag,* Tony Gherghetta, and Andrew S. Miller School of Physics and Astronomy, University of Minnesota, Minneapolis, Minnesota 55455, USA
(Received 9 December 2018; published 28 February 2019)
We consider a supersymmetric model that uses partial compositeness to explain the fermion mass hierarchy and predict the sfermion mass spectrum. The Higgs and third-generation matter superfields are elementary, while the first two matter generations are composite. Linear mixing between elementary superfields and supersymmetric operators with large anomalous dimensions is responsible for simulta- neously generating the fermion and sfermion mass hierarchies. After supersymmetry is broken by the strong dynamics, partial compositeness causes the first- and second-generation sfermions to be split from the much lighter gauginos and third-generation sfermions. This occurs even though the tree-level soft masses of the elementary fields are subject to large radiative corrections from the composite sector, which we calculate in the gravitational dual theory using the AdS=CFT correspondence. The sfermion mass scale is constrained by the observed 125 GeV Higgs boson, leading to stop masses and gauginos around 10–100 TeV and the first two generation sfermion masses around 100–1000 TeV. This gives rise to a splitlike supersymmetric model that explains the fermion mass hierarchy while simultaneously predicting an inverted sfermion mass spectrum consistent with LHC and flavor constraints. Finally, the lightest supersymmetric particle is a gravitino in the keV to TeV range, which can play the role of dark matter.
DOI: 10.1103/PhysRevD.99.035046
I. INTRODUCTION A knowledge of the sfermion mass spectrum has The Higgs boson discovery at the LHC [1–3] has led to important implications for collider and flavor experiments new constraints on the parameter space of supersymmetric seeking to discover supersymmetry. In split supersymmet- models. In particular, the explanation of the 125 GeV Higgs ric models, the supersymmetry-breaking scale occurs near – boson requires stop masses (or A-terms) which are large, the PeV scale, with sfermion masses in the range 10 ≳1 TeV, causing a significant increase in the tuning of 1000 TeV. Even though this hierarchy of sfermion masses supersymmetric models. In addition, in order to ameliorate seems unrelated to the fermion mass hierarchy, it begs the the supersymmetric flavor problem without any additional question as to whether these two hierarchies could in fact be structure, the first- and second-generation sfermions are explained by the same mechanism. For example, a novel required to have masses in the 100–1000 TeV range. way to account for the fermion mass hierarchy is the idea of Satisfying these two requirements leads to a version of partial compositeness [10]. New strong dynamics is respon- split supersymmetry [4,5] dubbed minisplit [6,7] which sible for operators with large anomalous dimensions that explains the 125 GeV Higgs boson while simultaneously linearly mix with elementary fermions. Assuming the maintaining the successful features of supersymmetric Higgs boson is elementary, a large Yukawa coupling then models such as gauge coupling unification and a dark arises for mostly elementary fermion mass eigenstates, matter candidate. Of course, this comes at the price of a while mostly composite fermion mass eigenstates have a meso-tuning, which may be a sign that we live in a correspondingly smaller Yukawa coupling. The hierarchy of Yukawa couplings is therefore explained by a set of multiverse [5], or instead could possibly be explained by operators with large, order-one anomalous dimensions. a relaxion mechanism [8,9]. If one now further assumes that the strong dynamics is responsible for breaking supersymmetry, then an interesting *[email protected] correlation between fermion and sfermion masses results † [email protected] from partial compositeness. Supersymmetric operators that ‡ [email protected] linearly mix with elementary fermions can now communi- cate supersymmetry breaking to the elementary sector. In this Published by the American Physical Society under the terms of way, composite sfermions obtain large supersymmetry the Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to breaking masses, while elementary sfermions obtain hier- the author(s) and the published article’s title, journal citation, archically smaller soft masses. The fermion mass hierarchy is and DOI. Funded by SCOAP3. therefore inversely related to the sfermion mass hierarchy:
2470-0010=2019=99(3)=035046(43) 035046-1 Published by the American Physical Society BUYUKDAG, GHERGHETTA, and MILLER PHYS. REV. D 99, 035046 (2019) light (elementary) stops correspond to heavy (elementary) masses arise from a singlet spurion and the other in a top quarks, while heavy (composite) selectrons are related to nonsinglet spurion case. We find that the observed Higgs the light (composite) electron. Together with the fact that mass naturally accommodates sparticle spectra that hier- gauginos and Higgsinos are predominantly elementary—and archically suppress the masses of the stops and the other therefore lighter than the composite sfermions—a “split” third-generation sfermions below the mass scale of the supersymmetric spectrum arises where the fermion mass first- and second-generation sfermions. In particular, if the hierarchy is naturally explained. It is the anomalous dimen- masses of the first- and second-generation sfermions are sions of the corresponding supersymmetric operators that restricted to be above 100 TeV to additionally suppress simultaneously controls the fermion and sfermion masses. flavor-changing neutral currents that arise in supersym- This contrasts with an alternative approach that radiatively metric models, the stop masses lie in the range 20–100 TeV, generates fermion masses from a sfermion anarchy [11]. while the masses of the lightest stau and neutralino may be A four-dimensional (4D), holographic description of as low as 10 TeV. Previous attempts to explain the sfermion partial compositeness for the fermion mass hierarchy mass hierarchy in a slice of AdS5 before the Higgs mass was previously considered in Refs. [12,13]. In this paper, was known were considered in Refs. [17,18]. The results we generalize this description to the supersymmetric case, obtained in this paper are the first predictions for the using results from Ref. [14]. Assuming that electroweak sfermion mass spectrum from partial compositeness that symmetry is broken in the elementary sector (with an are compatible with a 125 GeV Higgs boson. Additionally, elementary Higgs boson), we consider the linear mixing of we include for the first time the full one-loop radiative elementary superfields with supersymmetric operators in corrections to the bulk scalar soft masses squared, the Higgs- the 4D dual gauge theory. This mixing is responsible not sector soft terms, and the soft trilinear scalar couplings. For only for the fermion mass hierarchy but also for the stops and other UV-localized sfermions, these corrections transmission of the (dynamical) supersymmetry breaking provide the dominant soft mass contributions, and accord- in the composite sector to the elementary sector. This leads ingly have important phenomenological consequences. For to relations that determine the fermion and sfermion mass the Higgs sector, they control the breaking of electroweak hierarchy in terms of the anomalous dimensions of super- symmetry. symmetric operators. These type of theories are similar to A schematic diagram of a possible mass spectrum in the single-sector models of supersymmetry breaking which partially composite supersymmetric model is depicted in were originally proposed in Refs. [15,16] and further Fig. 1. It assumes an elementary Higgs sector interacting studied in Refs. [17–21]. A shortened version of this work with an elementary top quark sector (UV localized). The summarizing the main results can be found in Ref. [22]. first- and second-generation fermions are composites (IR The nonperturbative nature of the strong dynamics only localized) of a strongly coupled sector that is also respon- allows the sfermion mass spectrum to be qualitatively sible for dynamically breaking supersymmetry. The strong determined. To obtain a more detailed sfermion spectrum dynamics therefore leads to a sfermion mass spectrum that is consistent with a 125 GeV Higgs boson, we use the that is inversely related to the fermion mass spectrum. anti-de Sitter/conformal field theory (AdS=CFT) corre- Furthermore, the graviton supermultiplet is elementary, spondence to model the strong dynamics associated with and, since it couples gravitationally, the gravitino receives partial compositeness in a slice of five-dimensional anti-de Sitter space (AdS5) [23]. The supersymmetric Higgs sector is localized on the UV brane, while supersymmetry break- ing is confined to the IR brane. The supersymmetric matter fields are bulk fields with the top quark (light fermions) localized near the UV (IR) brane. In the dual, five-dimen- sional (5D) gravity description, the overlap of fermion profiles [24] with the UV-localized Higgs fields mimics the partial compositeness and explains the fermion mass hierarchy [25]. The Standard Model Yukawa couplings are used to constrain the bulk fermion profiles, which then determine the soft masses at the IR scale. Both the Higgs- sector soft masses and the soft trilinear scalar couplings arise at loop order, due to radiative corrections from the bulk that transmit the breaking of supersymmetry. FIG. 1. Schematic diagram depicting a possible particle spec- Renormalization group evolution is then used to run the trum of the partially composite supersymmetric model. The left soft masses down to the electroweak scale and obtain the (right) column depicts the fermions (bosons). The sfermion mass 125 GeV Higgs mass. Using this procedure, we analyze hierarchy is inversely related to the fermion mass hierarchy and two benchmark scenarios: one for the case that the gaugino the LSP is the gravitino.
035046-2 PARTIALLY COMPOSITE SUPERSYMMETRY PHYS. REV. D 99, 035046 (2019)
3 a small supersymmetry-breaking contribution, becoming is written as 2 þ δ, where δ denotes the deviation from the the lightest supersymmetric particle (LSP) with a mass canonical scaling dimension. The Lagrangian at the UV ≳1 Λ keV. This differs from other split-supersymmetry scale, UV, is taken to have the form models where the gravitino is usually the heaviest super- 1 partner. Finally, even though the first two generations of † μ c Lψ ¼ iψ σ¯ ∂μψ − ðψOψ þ : :Þ; ð Þ matter are composite, gauge coupling unification still Λδ−1 H c 1 UV occurs at approximately 1016 GeV, as in the usual super- symmetric standard model [assuming any underlying where the Minkowski metric ημν ¼ diagð−; þ; þ; þÞ and strong dynamics is SU(5) symmetric]. It should also be an order-one UV coefficient has been assumed in the noted that the elementary matter is present at the grand second term. The mixing term in (1) means that after unified theory (GUT) scale with order-one Yukawa cou- Λ confinement at an IR scale, IR, the mass eigenstates are an plings. This helps one to avoid the tension that occurs from admixture of elementary and composite states. This is Yukawa coupling unification in usual grand unification analogous to γ-ρ mixing in QCD. To obtain analytic scenarios, where the lighter first two fermion genera- estimates of this mixing, the strong dynamics is assumed tions are elementary (do not mix with a composite sector), to be described by a large-N gauge theory, where N is the and consequently have tiny Yukawa couplings at the number of colors. In the large-N limit, the two-point GUT scale. function for a compositeP operator, O can be written as The rest of this paper is summarized as follows: In hOðpÞOð−pÞi ¼ a2=ðp2 þ m2Þ to leading order in 1, Sec. II, we review the idea of partial compositeness in the n npffiffiffi n N ¼h0jOj i ∝ N O context of the fermion mass hierarchy. This is then where an n 4π is the matrix element for to th generalized to a supersymmetric model when supersym- create the n state from the vacuum and mn is the mass of metry is assumed to be broken by the strong dynamics. This that state [26]. gives rise to a sfermion mass hierarchy that inverts the Applying these results to fermions, we consider a simple fermion mass ordering. We then construct the gravitational three-state system containing an elementary Weyl fermion ψ dual of this model in a slice of AdS5 in Sec. III. The soft , together with a lowest-lying composite Dirac fermion ðψ ð1Þ ψ cð1ÞÞ ð1Þ ¼ ð1ÞΛ ð1Þ masses resulting from supersymmetry breaking on the IR ; , with mass, mψ gψ IR, where gψ is an brane are calculated, including one-loop radiative correc- order-one coupling. Note that having a composite Dirac tions from the bulk theory to the sfermions and Higgs fermion follows from assuming that the strong dynamics fields. In Sec. IV, we develop the parameter space available does not break any Standard Model gauge symmetries. The Λ in the 5D model and estimate the constraints arising Lagrangian at the scale IR is given by on this space from various phenomenological and † μ †ð1Þ μ ð1Þ †cð1Þ μ cð1Þ theoretical requirements. We select two representative Lψ ¼ iψ σ¯ ∂μψ þiψ σ¯ ∂μψ þiψ σ¯ ∂μψ benchmark scenarios and perform a full numerical analysis. −ε Λ ðψψcð1Þ þ Þ− ð1Þðψ ð1Þψ cð1Þ þ Þ ð Þ We conclude by presenting the resulting spectra. In ψ IR H:c: mψ H:c: : 2 Appendix A, we write down the partially composite theory below the confinement scale in terms of component fields, The dimensionless coupling εψ is defined at the IR scale and then determine the mass eigenstates resulting from the to be mixing of the elementary and composite sectors. Next, in pffiffiffiffi pffiffiffiffi 1 Λ δ−1 Appendix B, we summarize the zero-mode profiles for N IR N εψ ≡ ε˜ψ ðΛ Þ ¼ pffiffiffiffiffiffi fields in the bulk of a slice of AdS5, including their IR 4π Λ 4π Zψ UV deformations due to the presence of supersymmetry break- sffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffi 1 δ − 1 ing on the IR brane. Finally, in Appendix C, we derive the ≃ pffiffiffiffiffi ð Þ Λ ; 3 ζ IR 2ð1−δÞ one-loop radiative corrections to scalar soft masses ψ ðΛ Þ − 1 squared, the Higgs soft b-term, and the soft trilinear scalar UV couplings arising in the 5D theory after supersymmetry is ε˜ ε˜ ðμÞ μ d ψ ¼ broken on the IR brane. where the running parameter ψ satisfies dμ ðδ − 1Þε˜ þ ζ N ε˜3 ζ ψ ψ 16π2 ψ , ψ is an order-one constant due to II. PARTIAL COMPOSITENESS the (unknown) strong dynamics [12], and the coefficient Zψ is the wavefunction renormalization of the elementary A. The fermion mass hierarchy fermion. In the final expression we have taken the large-N We begin by briefly reviewing how partial composite- approximation of Zψ . ness explains the fermion mass hierarchy [12,13]. Consider The diagonalization of the Lagrangian (2) generates two sectors, an elementary sector with a Weyl fermion ψ fermionic admixtures of the elementary and composite and a composite sector with a (charge-conjugate) fermion states [27]. In particular, the massless fermion eigenstate is c operator Oψ. The scaling dimension of the fermion operator given by
035046-3 BUYUKDAG, GHERGHETTA, and MILLER PHYS. REV. D 99, 035046 (2019) pffiffiffi ε Φ ¼ ϕ þ 2θψ þ θθ ϕ jψ i ≃ N jψi − ψ jψ ð1Þi superfield F, where is a complex 0 ψ ð1Þ scalar field, ψ is a Weyl fermion, and F is an auxiliary field. gψ ( sffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffi ) In addition,p weffiffiffi introduce a supersymmetric chiral operator 1 1 δ − 1 O ¼ O þ 2θO þ θθO ≃ N jψi − pffiffiffiffiffi jψ ð1Þi ð Þ ϕ ψ F. The scaling dimension of the ψ ð1Þ Λ 4 ζ IR 2ð1−δÞ O ¼ 1 þ δ gψ ψ ðΛ Þ − 1 scalar operator is dim ϕ O, the scaling dimension UV 3 of the fermion operator is dim Oψ ¼ 2 þ δO, and the scaling where N ψ is a normalization constant. This expression dimension of the auxiliary operator is dim O ¼ 2 þ δO, shows that for δ ≥ 1 the mass eigenstate is mostly elemen- F where δO ≥ 0 [14]. 0 ≤ δ 1 tary, while for < the state has a sizeable composite The supersymmetric Lagrangian contains separate admixture. These admixtures play a crucial role in deter- elementary and composite sectors, together with linear mining mass hierarchies. mixing terms of the form ½ΦOc for each chiral superfield. ψ F At the UV scale, the chiral elementary fermions L;R are The superfield Lagrangian at the scale Λ is given by coupled to the elementary Higgs field H via the Yukawa UV interaction λψ ψ H, where λ is an order-one proto-Yukawa 1 L R † c LΦ ¼½Φ Φ þ ð½ΦO þ H:c:Þð6Þ coupling and the Higgs field is assumedpffiffiffi to develop a vacuum D Λδ−1 F UV expectation value (VEV) hHi¼v= 2. Diagonalizing the fermion Lagrangian at the IR scale with the Higgs contri- where Oc is the charge-conjugate composite operator with bution gives the fermion mass expression anomalous dimension δ and we have assumed an order-one UV coefficient.1 The composite sector is assumed to λ v 2 mψ ≃ pffiffiffiffiffiffiffiffiffiffiffi pffiffiffi N ψ confine at the infrared scale Λ , and thus, for the Z Z 2 IR 8 L R large-N strong dynamics, the two-point function hOOi is 2 > λ ðδ − 1Þ 16π pvffiffi δ ≥ 1; again assumed to be a sum over one-particle states. The < ζψ N 2 Lagrangian at the IR scale can be written as ≃ 2ð1−δÞ ð5Þ 2 Λ > λ 16π pvffiffi IR : ζ ð1 − δÞ Λ 0 ≤ δ < 1; ψ N 2 UV L ¼½Φ†Φ þ½Φcð1Þ†Φcð1Þ þ½Φð1Þ†Φð1Þ Φ D D D δ ≡ δ ¼ δ þε Λ ð½ΦΦcð1Þ þ Þþ ð1Þð½Φð1ÞΦcð1Þ þ Þ where for simplicity we have assumed that L R, Φ IR H:c: mΦ H:c: ; ð1Þ ð1Þ ð1Þ F F gψ ≡ gψ ¼ gψ , εψ ≡ εψ ¼ εψ , and explicitly included L R L R ð7Þ the normalization factor from (4). The wavefunction coef- 0 ≤ δ 1 ficients ZL;R are approximated as in (3), and for < we Φð1Þ Φcð1Þ ð1Þ where ( ) is the lowest-lying composite chiral have assumed εψ ≲ gψ . Notice that when δ ≥ 1 there is no O Oc ð1Þ ¼ ð1ÞΛ superfield corresponding to ( ) and mΦ gΦ IR is power-law suppression in the Yukawa coupling since the ð1Þ the lowest-lying resonance mass, with g an order-one mass eigenstates are mostly elementary and have order-one Φ coupling. Note that we have neglected heavier resonances couplings to the elementary Higgs field. This, for instance, and higher-order terms in (7). The Lagrangian contains would explain the Yukawa coupling of the top quark. This mixing terms between the elementary superfield Φ and the contrasts with the case 0 ≤ δ < 1, where the mass eigenstates Φcð1Þ have a sizeable composite admixture with a power-law lowest-lying composite superfield . The dimension- ε suppressed Yukawa interaction (due to the fact that the less constant Φ is defined at the IR scale to be proto-Yukawa coupling λ in the elementary sector is divided pffiffiffiffi pffiffiffiffi pffiffiffiffiffiffiffiffiffiffiffi 1 Λ δ−1 by the large wavefunction renormalization factor, Z Z ,at ε ≡ ε˜ ðΛ Þ N ¼ pffiffiffiffiffiffi IR N L R Φ Φ IR 4π ZΦ Λ 4π the IR scale). These states describe the remaining light 8 UV pffiffiffiffiffiffi δ−1 fermions in the Standard Model, where for each flavor i there > δ−1 Λ <> pffiffiffiffi IR δ > 1 is a corresponding operator with anomalous dimension δ . ζ Λ i ≃ Φ UV ð Þ Therefore, the hierarchical Yukawa couplings result from > pffiffiffiffiffiffi 8 > p1ffiffiffiffi−δ order-one anomalous dimensions of operators. In the super- : 0 ≤ δ < 1; ζΦ symmetric generalization, these anomalous dimensions also determine the magnitude of the corresponding sfermion dε˜Φ N 3 where ε˜Φ satisfies μ ¼ðδ − 1Þε˜Φ þ ζΦ 2 ε˜Φ, with ζΦ masses. dμ 16π an order-one constant. Note that the supersymmetric nonrenormalization theorem guarantees that εΦ only B. Supersymmetric partial compositeness depends on the wavefunction renormalization, unlike the 1. Chiral supermultiplet 1A kinetic mixing between the elementary and composite Next, we consider the supersymmetric generalization of Λ−δO ½Φ†O þ sectors of the form UV H:c: D has been omitted in our partial compositeness. Consider the elementary chiral minimal setup.
035046-4 PARTIALLY COMPOSITE SUPERSYMMETRY PHYS. REV. D 99, 035046 (2019) 1 1 nonsupersymmetric case, where the vertex renormalization L ¼ ½ α þ ½ ð1Þα ð1Þ þ piece in (3) was neglected. V 4 W Wα F 4 W Wα F H:c: Just as for the fermions in Sec. II A, the mixing terms in ð1Þ ð1Þ† 2 ð1Þ Φ þ Φ the Lagrangian (7) cause the scalar mass eigenstates to be þ Λ2 ε V þ g Vð1Þ þ Vpffiffiffi V ; ð11Þ IR V V 2Λ admixtures of elementary and composite states. The details IR D of this mixing are given in Appendix A. Using the result ð1Þ (A4) and (8), the massless scalar eigenstate ϕ0 is given by where gV is the composite vector coupling,pffiffiffi and the ε ≡ ε˜ ðΛ Þ N ( sffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffi ) dimensionless constant, V V IR 4π parametrizes 1 δ − 1 ε˜ ðμÞ jϕ i ≃ N jϕi − jϕð1Þi ð Þ the mixing at the IR scale. The running parameter V 0 Φ pffiffiffiffiffiffi Λ ; 9 dε˜ 3 ð1Þ IR 2ð1−δÞ μ V ¼ ζ N ε˜ ζ g ζΦ ð Þ − 1 satisfies μ V 16π2 V, with V an order-one constant Φ ΛUV d that comes from the (unknown) strong dynamics. This where ϕ is an elementary scalar, ϕð1Þ is the lowest-lying immediately leads to the solution composite scalar, and N Φ is a normalization constant. 1 1 4π Similarly to the fermion case (4), the massless scalar ε˜ ðΛ Þ¼qffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffi ≃qffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffipffiffiffiffi; ð12Þ V IR 1 ζ Λ Λ þ V N ð UVÞ UV N eigenstates are mostly elementary for δ > 1, whereas for ε˜2 8π2 log Λ 2ζV logð Λ Þ V IR IR 0 ≤ δ < 1 they are an admixture of elementary and composite states. In fact, supersymmetry guarantees that where we have taken the large-N limit in the last term. the admixtures for both the fermion and scalar field in the The Lagrangian (11) can be diagonalized to obtain the chiral multiplet are the same. mass eigenstates (the details are given in Appendix A). Using (A15), the massless gauge boson eigenstate is found 2. Vector supermultiplet to be 8 9 Next, we consider the supersymmetric generalization of < = partial compositeness for gauge fields. For simplicity, we 1 ð1Þ jAμ0i ≃ N jAμi − qffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffi jAμ i ; ð13Þ V: ð1Þ Λ ; consider the case of an Abelian U(1) gauge field, and 2ζ ð UVÞ gV V log Λ assume our discussion can be generalized to non-Abelian IR gauge fields. In the nonsupersymmetric case, the source ð1Þ where N V is the normalization constant and Aμ is the field Aμ mixes with the conserved U(1) current Jμ and μν ð1Þ lowest-lying composite gauge boson. Assuming a large induces a kinetic mixing of the form F Fμν [27,28], where hierarchy (Λ ≫ Λ ) and order-one values for the ð1Þ UV IR Fμν is the field strength of the lowest-lying composite field, couplings, this expression shows that the massless eigen- ð1Þ Aμ . To supersymmetrize this coupling we introduce state is mostly elementary, but with a sizeable composite † μ † † † † admixture. The corresponding gauge coupling for this the vector superfield, V ¼ θ σ¯ θAμ þ θ θ θλ þ θθθ λ þ 1 † † massless state is given in (A20). θθθ θ D, with field strength superfield Wα ¼ λαþ 2 The gaugino part of the Lagrangian (11) is similarly θ þ i ðσμσ¯ νθÞ þ θθðσμ∂ λ†Þ αD 2 αFμν i μ α. The conserved cur- given in Appendix A, where it is shown to be a special case rent Jμ can be embedded into a linear supermultiplet J , (δ ¼ 1) of the fermion Lagrangian (2). After diagonalizing 2 †2 which satisfies the condition D J ¼ D J ¼ 0 and guar- the mass terms (see Appendix A), the massless gaugino antees current conservation [29]. eigenstate becomes The supersymmetric Lagrangian at the UV scale is 8 9 given by < = 1 ð1Þ jλ0i ≃ N jλi − qffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffi jλ i ; ð14Þ V: ð1Þ Λ ; 1 UV α g 2ζV logð Λ Þ L ¼ ½ þ þ 2ε˜ ½ J ð Þ V IR V 4 W Wα F H:c: V V D; 10 where we have used (A24) and λð1Þ represents the lowest- ε˜ ½ J where V is the mixing parameter. Since V D can be lying composite gaugino. By supersymmetry, the overall ½ αW þ N transformed into a kinetic term such as W α F H:c:, normalization constant, V, and composite admixture are where W is the field-strength superfield operator associated the same as in (13). with a composite vector superfield operator V,weomit such a term in the Lagrangian. 3. Gravity supermultiplet After confinement, the IR Lagrangian for the source V, ð1Þ Next, we consider the supersymmetric generalization of together with the lowest-lying composite vector V , field- partial compositeness for gravity fields. In the nonsuper- ð1Þ Φð1Þ strength superfield Wα , and chiral adjoint superfield V , symmetric case the graviton hμν mixes with the conserved can be written as energy-momentum tensor Tμν, inducing a kinetic mixing
035046-5 BUYUKDAG, GHERGHETTA, and MILLER PHYS. REV. D 99, 035046 (2019) 1 Λ between the graviton and massive spin-2 resonances [27] IR ð1Þ jhμν0i ≃ N jhμνi − pffiffiffiffiffiffi jhμν i : ð20Þ (which is completely analogous to graviton-f2 mixing in H ð1Þ ζ Λ gH H UV QCD). In the supersymmetric extension, the graviton hμν and gravitino ψ μ can be embedded into the real super- Λ ≪ Λ Assuming IR UV, this shows that the massless eigen- gravity field, state is mostly elementary with a tiny composite admixture. The gravitino part of the Lagrangian (17) is given in 1 † ν † † † † Appendix A, where it is shown to be a special case (δ ¼ 2) Hμ ¼ −pffiffiffiðθ σ¯ θÞhμν − iθθθ λμ þ iθ θ θλμ þ ; ð15Þ 2 of the fermion Lagrangian (2). After diagonalizing the mass terms (see Appendix A), the massless gravitino eigenstate 1 1 ρ where we have assumed the gauge 2 ψ μ ≡ λμ þ 3 σμσ¯ λρ becomes and only written the graviton and gravitino parts. The 1 Λ conserved energy-momentum tensor Tμν can be embedded jψ i ≃ N jψ i − IR jψ ð1Þi ð Þ μ0 H μ ð1Þpffiffiffiffiffiffi μ ; 21 into the supercurrent Θμ, which satisfies the condition Λ g ζH UV μ † H −iσ¯ DΘμ ¼ D X, where X is an antichiral superfield, and μν ð1Þ guarantees current conservation: ∂μT ¼ 0 [29]. The where we have used (A38) and ψ μ represents the lowest- supersymmetric Lagrangian at the UV scale is given by lying composite gravitino. By supersymmetry, the composite admixture is the same as in (20), and thus the 4 2ε˜ μ H μ gravitino is again mostly elementary. L ¼ ½HμE þ ½HμΘ ; ð16Þ H 3 D Λ D UV
μ C. Supersymmetry breaking where ε˜H is the mixing parameter and E is the Einstein superfield [30]. In an analogous fashion to the gauge boson Supersymmetry is assumed to be broken in the composite case, the IR Lagrangian after confinement can be written as sector by the strong dynamics and will be parametrized by a composite spurion, chiral superfield, X ¼ θθF, where the vacuum expectation value hFi ≡ FX ≠ 0.Inthelarge-N 4 μ 4 ð1Þ ð1Þμ pffiffiffi L ¼ ½ þ ½ μ 2 H HμE D H E D ∝ N Λ 3 3 limit, we have FX 4π IR [31]. 2 μ ð1Þ ð1Þ 2 þ 2Λ ½ðεHH þ g Hμ Þ ; ð17Þ IR H D 1. Sfermion masses pffiffiffi ε ¼ ε˜ ðΛ Þ N ð1Þ Supersymmetry-breaking scalar masses are only gener- where H H IR 4π and Hμ is a composite real super- field with corresponding Einstein superfield Eð1Þμ.The ated for the composite sector fields, since there is no direct ε˜ μ ε˜ coupling of the supersymmetry-breaking spurion to the pffiffiffiffiffiH d H running parameter ε˜HðμÞ ≡ Λ satisfies μ μ ¼ ε˜H þ ZH UV d elementary fields. For instance, the massive chiral super- ζ N ε˜3 ζ ð1Þ H 16π2 H,with H an order-one constant that arises from the field Φ directly couples to the supersymmetry breaking (unknown) strong dynamics. The solution is then given by in the composite sector via the following D-term:
Λ 1 1 Λ 4π ð1Þ2 2 IR rffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffi pffiffiffiffiffiffi IR pffiffiffiffi gΦ † ð1Þ† ð1Þ ð1Þ2 jFX j ð1Þ† ð1Þ ε˜HðΛ Þ¼ ≃ ; ξ ½X XΦ Φ ¼ ξ ϕ ϕ ð Þ IR Λ ζ Λ 4 2 D 4gΦ 2 ; 22 UV 1 ζ Λ 2 H UV N Λ Λ þ HN 1 − ð IR Þ IR IR ε˜2 16π2 Λ H UV ð Þ where ξ4 is a dimensionless parameter, which for a large-N 18 16π2 gauge theory is proportional to N [26]. This D-term where, in the last term, we have taken the large-N limit. Since interaction gives a supersymmetry-breaking mass to the the graviton couples to the energy-momentum tensor with composite scalar field ϕð1Þ. Given the scalar admixture (9), 18 strength 1=MP (where MP ¼ 2.4 × 10 GeV is the reduced the corresponding sfermion mass squared becomes 1 εH Planck mass), we obtain the matching condition ≡ Λ at 8 MP IR ðδ−1Þ Λ 2ðδ−1Þ j j2 < IR FX 2 ζ ðΛ Þ ξ4 2 δ ≥ 1; the IR scale, which leads to the relation jFX j Φ UV Λ ˜ 2 ≃ N 2 ε2 ξ ≃ IR m Φ Φ 4 2 2 sffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffi Λ : ð1−δÞ jFX j IR ξ4 2 0 ≤ δ < 1; 2 ζΦ Λ pffiffiffiffiffiffi Λ pffiffiffiffiffiffi IR ≃ ζ Λ 1 − IR ≃ ζ Λ ð Þ MP H UV Λ H UV: 19 ð Þ UV 23
ð1Þ The Lagrangian (17) contains mass mixing terms, and the where we have assumed εΦ ≲ gΦ . Note that the sfermion diagonalization details are given in Appendix A. Using mass is power-law suppressed for δ > 1. This is because the (A32), the massless graviton eigenstate is found to be mass eigenstate is mostly elementary and therefore can
035046-6 PARTIALLY COMPOSITE SUPERSYMMETRY PHYS. REV. D 99, 035046 (2019) only obtain a supersymmetry-breaking mass via mixing generically lighter than the heavy composite sfermions with the composite sector. This contrasts with the case with 0 ≤ δ < 1, leading to a “split” spectrum. 0 ≤ δ < 1, where the mass eigenstate has a sizeable However when δ is greater than the critical value δ , the composite admixture and therefore directly feels the gaugino mass radiative correction (24) gives the dominant supersymmetry breaking from the composite sector without contribution to the scalar masses. The critical value δ any power-law suppression. In this way, a sfermion mass occurs when δm˜ 2 ≃ m˜ 2, and using (26) it takes the value hierarchy can be explained by anomalous dimensions of h i 4π Λ ð UVÞ supersymmetric operators. log g log Λ δ δ ≃ 1 þ i IR ; ð27Þ Note, however, that as is increased beyond one, the ΛUV logð Λ Þ scalar mass squared becomes increasingly small, since the IR scalar is becoming more elementary [using (9)]. Eventually, where we have included only the dominant gauge-coupling radiative corrections are sufficiently large that they provide contribution. Thus, for δ > δ , the gaugino is heavierpffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffi than the dominant contribution to the sfermion mass squared. α ð4πÞ the corresponding sfermionpffiffiffiffiffiffiffi mass by a factor of i= . For instance, the sfermion-fermion-gaugino interaction ≫ Λ Note that when FX IR, the lightest gaugino with a massive gaugino leads to the one-loop contribution becomes a Dirac fermion with a mass 2 Λ 2 g 2 IR δ ˜ ≃ i ð Þ Mλ ≃ ε Λ ≃ qffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffi : ð28Þ m 2 Mλ ; 24 V IR Λ 16π i 2ζ logð UVÞ V ΛIR ¼ 1 ð1Þ where gi (i , 2, 3) are the Standard Model U Y × This value parametrically matches the gaugino mass that ð2Þ ð3Þ SU L ×SU gauge couplings, respectively. Note that is found in a five-dimensional (5D) supersymmetric stan- this radiative correction is assumed to be finite. Therefore, dard model where supersymmetry breaking arises from δ there is a maximum value of the anomalous dimension , “twisted” boundary conditions [17]. The Dirac limit can beyond which the gaugino-mediated contribution (24) also be seen in Fig. 2, which shows the elementaryp stateffiffiffiffiffiffiffi dominates. ð1Þ λ marrying the composite Weyl fermion χ as FX ∼ ðΛ ÞΛ becomes larger, giving rise to a Dirac mass gs IR IR 2. Gaugino masses pthatffiffiffiffiffiffiffi is smaller than the mass (A26) that applies when ≪ Λ The spurion superfield X can also be used to generate FX IR. gaugino masses. Since the massless gaugino (14) contains a λð1Þ admixture, supersymmetry breaking in the composite 3. Gravitino masses sector is transmitted by the following interactions: The supersymmetry breaking from the composite sector gives rise to a positive vacuum energy. This contribution ξ ð1Þ2 can be cancelled by introducing a constant superpotential 3 gV ð½X αð1Þ ð1Þ þ Þ ð Þ 2 Λ W Wα F H:c: ; 25 W, which induces a mass term for the elementary gravitino IR 1 4π W μ ρ where ξ3 is proportional to pffiffiffi for a large-N gauge theory. − ψ ρ½σ ; σ¯ ψ μ þ H:c: ð29Þ N 4 M2 The supersymmetry-breaking interaction (25), adds the P ð1Þ2 FX ð1Þ ð1Þ 10 Majorana mass term ξ3g λ λ þ H:c: to the gau- V 2ΛIR gino mass terms in (A21). Note that there is no χð1Þ mass ð1Þ2 ½X 1 term because the interaction V D is not gauge invariant. Diagonalization of the mass matrix then leads to a gaugino mass
/ 0.100 M ¼ N 2 ε2 ξ FX ≃ 2ξ FX ð Þ Mλ V V 3 Λ g 3 Λ ; 26 IR IR 0.010 where we have used the gauge coupling relation (A20) and ε ≃ ðΛ Þ 0.001 V gs IR . The result (26) is consistent with simply 0.01 0.10 1 10 100 using (14) and the fact that the massless mode only has a F / λð1Þ admixture. Notice that the gaugino mass is suppressed by a logðΛ =Λ Þ factor due to the fact that the elemen- ð1Þ ¼ 2 ε ¼ 0 3 UV IR FIG. 2. Gaugino mass eigenvalues for gV , V . , and tary gaugino mixes with the composite sector via a ξ3 ¼ 1 as a function of the supersymmetry-breaking order marginal coupling. This causes the gauginos to be parameter FX.
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At the IR scale, this term becomes the gravitino is generically much lighter than the heavy composite sfermions with 0 ≤ δ < 1. There is also a heavy 1 ð1Þ ð1Þ − W ψ ½σμ σ¯ ρ ψ þ Dirac gravitino mostly comprised of ψ μ and χμ with mass 2 ρ ; μ H:c: ð1Þ2 4ZH M ∼ð þ ε2 Þ1=2Λ P gH H IR. 1 4π FX ≫ Λ ≃− pffiffiffiffi pffiffiffi ψ ½σμ σ¯ ρ ψ þ ð Þ In the opposite limit FX IRMP, one gravitino Weyl 2 ρ ; μ H:c:; 30 4ζ ε˜ state decouples, and the elementary state ψ μ marries the H H N 3MP ð1Þ composite state ψ μ [17] such that the lightest gravitino ε˜ ðΛ Þ ð1Þ where ZH is defined from H IR in Sec. II B 3 and in ≃ Λ 2 then becomes a Dirac fermion with a mass m3=2 gH IR. j j2 N ≃ 3 jWj the second equation, we have tuned FX 16π2 2 so that This is similar to what occurs for the gaugino, except that MP the cosmological constant vanishes. Note that this means the since the mixing is very small, the Dirac limit is reached elementary sector is supersymmetric AdS4, with Minkowski much more slowly for the gravitino. space obtained after the “uplift” from the supersymmetry- breaking composite sector. Diagonalization of the mass 4. Higgs soft mass matrix [given in (A36)] with the inclusion of (30) then leads There is no direct coupling of the supersymmetry- to a gravitino mass breaking spurion to the elementary fields, and therefore the Higgs soft mass can only be generated radiatively, via FX m3 2 ≃ ξ3 pffiffiffi ; ð31Þ loops of fields with a composite admixture. In particular, = 3 MP gaugino and sfermion loops can transmit the supersym- metry-breaking effects to the elementary sector. ≪ Λ N ≃ 1 ξ ¼ 1 p4πffiffiffi where FX IRMP, H , and 3 ζ ε˜2 . The result H H N The first type of sfermion contributions are due to (31) is consistent with simply using (21) and the fact that Yukawa interactions. These lead to the Higgs soft mass Λ ≪ the massless mode is mostly elementary. Since IR MP, squared
y2ðΛ Þ Λ ðΔm2 Þ ≃ δ IR m˜ 2 log IR H y 16π2 TeV λ2 N 2 Λ ≃ Φ m˜ 2 log IR 16π2 Z2 TeV Φ 16π2λ2 N 4 δ − 1 3 Λ 2ðδ−1Þ j j2 Λ ≃ Φ IR ξ FX IR ð Þ 2 3 Λ 4 2 log ; 32 ζ IR 2ðδ−1Þ Λ Λ N Φ 1 − ð Þ UV IR TeV ΛUV ðΛ Þ ≡ h i δ ¼ δ ¼ δ λ where yδ IR mψ = H is the Yukawa coupling from Sec. II A with L R chosen for simplicity, is the proto- Yukawa coupling, N Φ is a normalization constant given in (A4), and ZΦ is defined in (8). − Φð1Þ The second type of sfermion corrections are due to D-term gauge interactions and the mixing term V V . Since the Φð1Þ scalar and the auxiliary field component of V mediates the supersymmetry breaking, the easiest way to estimate the Φð1Þ D-term contribution is to approximately solve for V in order to determine how the elementary D-term is coupled to the composite sfermions. This procedure generates the following correction: 0 1 2 g1ðΛ Þ B Λ N C ðΔm2 Þ ≃ YðHÞYðϕÞ IR ε @log IR þ Φ Am˜ 2 H D 8π2 V m2 TeV 2ε2 1 þ Φ1 Φ Λ2 0 IR 1
ΛIR 2 2 g1ðΛ Þ Blogð Þ δ − 1 N C jFX j ≃ ð Þ ðϕÞ IR ε N 2 @ TeV þ Φ Aξ ð Þ Y H Y 2 V Φ Λ 2ð1−δÞ 2 4 2 ; 33 8π ζ ð IR Þ − 1 mΦ Λ Φ Λ 2 1 þ 1 IR UV Λ2 IR ð1Þ 2 ¼ðε2 þ ð1Þ2ÞΛ2 where g1 is the U Y gauge coupling, Y denotes the hypercharge, and mΦ1 Φ gΦ IR. Finally, the corrections that involve gauginos arise from gauge interactions. The dominant contribution is given by g2ðΛ Þ Λ ðΔm2 Þ ≃ 4CðR ÞN 2 2 IR M2 log IR ; ð34Þ H g H V 8π2 λ TeV
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100 κ ( m ) where μ is a dimensionless coupling. Assuming that the 50 H g2 Peccei-Quinn symmetry is spontaneously broken by a ( m ) H g1 nonzero vacuum expectation value hSi ∼ f, an effective 10 μ-term of size 5
[TeV] 2 κμf H μ ≃ ð36Þ m ( m ) H y 2MP 1 0.5 ( mH)D is then generated. Since the global symmetry is anomalous (and assuming all other sources of breaking are small), the
0.1 pseudo Nambu-Goldstone boson associated with the spon- 0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 taneous symmetry breaking can be identified with the axion. This axion is of the invisible DFSZ type, and is FIG. 3. One-loop corrections to the Higgs mass parameter that consistent with the present astrophysical constraints pro- 109 ≲ ≲ 1012 arise from gauge, Yukawa, and D-term interactions due to a vided that GeV f GeV. For this range of f, single sfermion or gaugino as a function of the anomalous the μ-term (36) can easily accommodate values in the dimension δ. range 0.1 TeV ≲ μ ≲ 100 TeV. Thus, using the Kim-Nilles mechanism, we can solve the strong-CP problem and generate the required values of the μ term. where g2 is the SU(2) gauge coupling and CðRÞ is the quadratic Casimir of the representation R. In Fig. 3,we E. The sfermion mass hierarchy plot the approximate expressions (32), (33), and (34) In a supersymmetric model, partial compositeness relates for a singlepffiffiffiffiffiffiffiffiffiffiffiffi sfermion [with YðϕÞ¼1] and gaugino, ξ ζ ¼ξ ¼ð4 75 1010 Þ2 Λ ¼ the fermion and sfermion mass hierarchies. To explicitly assuming 4= ΦFX 3FX . × GeV , IR ð1Þ ð1Þ 2 ð1Þ2 see this relation we consider a numerical example involving 16 ΛIR 16π 2 2 × 10 GeV, ≃ 0.026, gΦ gΦ λ ≃ 1, g ≃ g5k, ΛUV L R N V the electron and the top quark. In order to explain the ð1Þ2 and ζΦ ≃ 1=g , where i ¼ L, R. Furthermore, for later fermion mass hierarchy, the top quark must be mostly i;V Φi;V 2 elementary with δ > 1 (i.e., irrelevant mixing), while the comparison with the 5D calculation, we use values for m t Φ1 electron must have a sizeable composite admixture with and m2 corresponding to the 5D Kaluza-Klein masses. V1 0 < δe < 1 (i.e., relevant mixing). Using the fermion mass Only the maximal contribution arising from the Yukawa expressions (5), the ratio of the Yukawa couplings at the IR δ ¼ δ δ ¼ 1 interaction (corresponding to L and R ) is shown scale is then given by in the figure. All contributions are qualitatively similar to 2ð1−δ Þ the precise 5D results that are given in Sec. III C and 1 − δ Λ e ye ≃ e IR ð Þ calculated in Appendix C. δ − 1 Λ : 37 yt t UV
D. Higgsino mass The ratio of the electron to the top-quark Yukawa coupling is determined in terms of δ , and for a sufficiently large Since the Higgs supermultiplet is elementary, there is no e;t hierarchy between Λ and Λ , depends sensitively on the direct coupling to the supersymmetry-breaking spurion in IR UV anomalous dimension δ . It is plotted in Fig. 4 for various the composite sector, and therefore the generation of a μ- e values of Λ =Λ , assuming that the Yukawa coupling term via a Giudice-Masiero mechanism [32] is forbidden. IR UV ratio is approximately y =y ≃ 10−5 over most IR scales. Instead, to generate a sizeable μ-term, we consider the e t Note that (37) is a simplified expression for δ values not Kim-Nilles mechanism [33] and introduce an elementary very close to one, but exact expressions are used in the Standard Model singlet S, together with a global U(1) figure. Peccei-Quinn symmetry, where H , H , S have the charges u d Using the sfermion mass expressions (23) and (24),we þ1, þ1, −1, respectively.2 This global symmetry then similarly obtain the ratio of the selectron mass squared to allows the following nonrenormalizable superpotential the stop mass squared at the IR scale: term: 8 2ð1−δ Þ > 1−δ Λ t κ 2 < e IR δ δ μ 2 δ −1 Λ t < t ; W ¼ S H H ; ð35Þ me˜ ¼ t UV ð Þ KN 2 u d 2 38 MP m > 4π 2 Λ t˜ :> ð1 − δ Þlog UV δ ≥ δ : α3 e ΛIR t t 2To allow for Yukawa interactions with the Higgs fields, the fermions Q, L, u¯, d¯, e¯ must have charges −1, −1,0,0,0, Note that this expression is separately valid for left- and respectively. right-handed scalar masses and only the gluino contribution
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1 Z –16 compactified on a S = 2 orbifold of radius R. The 10 spacetime metric is anti-de Sitter, given by 0.8 10–10 2 −2kjyj μ ν 2 M N ds ¼ e ημνdx dx þ dy ≡ gMNdx dx ; ð39Þ 10–7 0.6 where k is the AdS curvature scale and capital Latin indices M ¼ðμ; 5Þ label the 5D coordinates. The 5D spacetime is a –5 10 slice of AdS5 geometry, bounded by two 3-branes located e at the orbifold fixed points: a UV brane at y ¼ 0 and an IR 3 0.4 10–4 brane at y ¼ πR. Λ ¼ The cutoff scale of the UV brane is UV M5, where 350 100 200 40 M5 is the 5D Planck scale, while the scale of the IR brane is Λ ¼ Λ e−πkR. The 4D reduced Planck mass, M ,is 0.2 10 IR UV P 10–3 given by [23]
M3 M3 M2 ¼ 5 ð1 − e−2πkRÞ ≃ 5 ; ð40Þ 0.0 P k k 1.0 1.2 1.4 1.6 1.8 where we are assuming πkR ≫ 1. Note that this expression t is consistent with the result (19) derived from partial compositeness. In order for the classical metric solution FIG. 4. Values of the anomalous dimensions δe and δt that give rise to the electron to top-quark Yukawa coupling ratio. The to be valid, the AdS curvature must be small enough approximately horizontal lines are contours of the ratio ΛIR=ΛUV, compared to the 5D Planck scale so that higher-order while the approximately vertical lines are contours of the tree- curvature terms in the 5D gravitational action can be level sfermion mass ratio me˜ =mt˜. The running of the Yukawa neglected. This requires k=M5 ≲ 2 [37], but, in the follow- Λ ¼ 1018 couplings has been included, assuming UV GeV, ing, we have taken k to be generically smaller, choos- β ¼ 3 tan , and a supersymmetric mass threshold at 50 TeV. ing k=M5 ¼ 0.1. Besides gravity, we introduce the matter and gauge field is included in (24) for the gaugino-mediated contribution to content of the minimal supersymmetric standard model the stop mass squared. Interestingly, the two expressions (MSSM) in the bulk. Since only Dirac fermions are allowed by the 5D Lorentz algebra, the bulk supersymmetry has (37) and (38) differ only in the exponents for δt < δt , while N ¼ 2 for δt ≥ δt the ratio no longer depends on δt. As shown in eight supercharges, corresponding to supersym- Fig. 4, the allowed region is 0 ≲ δe ≲ 0.9 and 1 ≲ δt ≲ 1.8, metry (SUSY) from the 4D perspective. All fields that Λ Λ N ¼ 2 depending on the value of IR= UV. The largest value of propagate in the AdS bulk are thus in representa- Λ the ratio me˜ =mt˜ is approximately 140 (390) for IR= tions of supersymmetry, but the orbifold compactification Λ ≃ 10−3ð10−16Þ breaks this to an N ¼ 1 supersymmetry at the massless UV . Note that the Yukawa coupling ratio level, preserving four supercharges [17,25]. The massless contours in Fig. 4, end at δt because the sfermion mass ratio becomes approximately constant as seen in (38). modes which form this 4D MSSM are the zero-mode Although these are naïve tree-level results obtained at the solutions in the Kaluza-Klein (KK) decompositions of the IR scale, they clearly reveal an inverted mass hierarchy for 5D fields. the sparticle spectrum where me˜ =mt˜ ∼ 10–350. To obtain a The zero-mode profiles for the bulk fields are summa- physical mass spectrum, this range is further restricted due rized in Appendix B. In a bulk hypermultiplet, the fermion to renormalization group (RG) effects. We next include and scalar zero-mode profiles depend on the bulk fermion these effects, as well as a number of phenomenological mass parameter c. By the AdS=CFT correspondence, the constraints, such as the 125 GeV Higgs boson. Since the scaling dimension of fermionic operators in the 4D dual 3 1 strong dynamics is nonperturbative, the AdS=CFT corre- theory is dim Oψ ¼ 2 þjc 2 j, and for scalar operators it 1 spondence is used to calculate the mass spectrum in a slice is dim Oϕ ¼ 1 þjc 2 j, where the upper (lower) sign is of five-dimensional AdS. used for left-handed (right-handed) fields. Thus, there is 1 direct relation δi ¼jci 2 j between the anomalous dimen- III. THE FIVE-DIMENSIONAL PICTURE sions δi in the 4D dual theory (introduced in Sec. II B) and A. Supersymmetry in a slice of AdS 3We do not specify a particular mechanism to stabilize We consider a warped five-dimensional spacetime μ the extra dimension. In a supersymmetric theory, one possibility ðx ;yÞ, where μ ¼ 0, 1, 2, 3 are the 4D coordinates and is supersymmetrization of the Goldberger-Wise mechanism −πR ≤ y ≤ πR is the coordinate of an extra dimension [34–36].
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second-generation sfermions are IR localized. Due to the properties of localization, the effective coupling strength of each superfield on the IR brane is inversely related to its coupling strength on the UV brane. Therefore, when supersymmetry is broken on the IR brane, as discussed in Sec. III C, the localization of the sfermions induced by the fermion mass spectrum results in an inverted scalar soft mass spectrum: light fermions have heavy superpartners, while heavy fermions have light superpartners. We next construct the details of this distinctive supersymmetric particle spectrum.
FIG. 5. Schematic diagram of the 5D model with the Higgs B. The fermion mass hierarchy fields, Hu;d, localized on the UV brane and supersymmetry broken on the IR brane. The Yukawa coupling hierarchy requires Consider first the generation of the fermion mass ψ ð0Þ hierarchy [25,38]. In our 5D spacetime, the SM fermion that the lighter first- and second-generation fermions 1;2 (and ð0Þ mass hierarchy is determined from the overlap of the bulk their superpartners ϕ˜ ) are IR localized (dark gray line) and the 1;2 SM fermion zero modes with the UV-localized Higgs ψ ð0Þ heavier, third-generation fermions 3 (and their superpartners fields. The Yukawa interactions take the form ϕ˜ ð0Þ 3 ) are UV localized (light gray line). The vector super- Z ð0Þ ð0Þ pffiffiffiffiffiffi multiplet, Aμ and λ , (dashed line) is not localized, while ¼ 5 − ð5Þ½Ψ¯ ð μ ÞΨ ð μ Þþ ð μÞδð Þ ð0Þ ð0Þ S5 d x gYij iL x ;y jR x ;y H:c: H x y the gravity multiplet, hμν and ψ˜ μ , (dotted line) is UV localized. Z ≡ 4 ½ ψ¯ ð0Þð μÞψ ð0Þð μÞ ð μÞþ þ ð Þ d x yij iL x jR x H x H:c ; 41 the bulk fermion mass parameters ci. Furthermore, for a bulk vector supermultiplet, the zero-mode profiles of the ð5Þ ¼ 1 where the Yij (with flavor indices i, j , 2, 3) are gauge field and gaugino field are flat, such that the bulk dimensionful (inverse mass) 5D Yukawa couplings, Ψ ð Þ 1 L R mass parameter of the Majorana fermion gaugino is c ¼ . ð2Þ 2 is a Dirac spinors that contains an SU L doublet (singlet) Similarly, the gravity supermultiplet contains a graviton of the MSSM as its zero mode, and H is the appropriate −ky 3 4 with the UV-localized zero mode (∝ e ) and a spin-2 Higgs field. Using the 5D fermion zero-mode profiles Rarita-Schwinger fermion (the gravitino), whose bulk mass (B3), the effective 4D SM Yukawa couplings yij are then 3 parameter is fixed to be c ¼ 2. given by [25] The warped geometry naturally generates a separation of ¼ ð5Þ ˜ ð0Þð0Þ˜ ð0Þð0Þ scales that can be used to explain the hierarchy between the yij Yij fiL fjR scale of supersymmetry breaking and the Planck scale. The sffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffis ffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffi 1 − c 1 þ c IR brane is therefore identified with the scale where ¼ ð5Þ 2 iL 2 jR ð Þ Yij k 2ð1− Þπ 2ð1þ Þπ : 42 supersymmetry is broken; the bulk and UV brane remain e 2 ciL kR − 1 e 2 cjR kR − 1 supersymmetric. The Higgs fields are localized on the UV ð5Þ brane, while the rest of the MSSM fields propagate in the By assuming that the dimensionless 5D couplings Y k are bulk and couple to the Higgs fields with brane-localized ij of order one, and since πkR ≫ 1, the hierarchy in the 4D Yukawa couplings. As discussed in Sec. III B, the degree of Yukawa couplings y is generated by the order one bulk overlap between a particular bulk fermion zero-mode ij profile and a UV-localized Higgs field determines its mass parameters ci of the fermions. Recall that in the 4D effective 4D Yukawa coupling and thus the size of the dual theory, this is equivalent to choosing the anomalous δ corresponding fermion mass. In this setup, third-generation dimensions i. fermions are therefore UV localized, whereas the lighter After electroweak symmetry breaking, the neutral com- ¼ first- and second-generation fermions are more IR local- ponents of each MSSM Higgs doublet acquire VEVs, vu h 0i ¼h 0i β ≡ ized. Including the SM gauge fields, the gauginos, and Hu and vd Hd , which are related by tan vu=vd, gravity, a full schematic diagram of the 5D model is and the fermions obtain masses depicted in Fig. 5. ð Þ ¼ð Þ β ð Þ Since the localization of the fermion in each chiral me ij ye ijv cos ; 43a supermultiplet determines the corresponding scalar localization, this 5D fermion geography has distinctive 4Use of the zero-mode approximation for the profiles, where consequences in the SUSY sector: the third-generation the backreaction of the boundary Higgs-generated fermion mass 2 Λ2 ≪ 1 sfermions are generally UV localized and the first- and is neglected, is a valid approximation provided v = UV .
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ð Þ ¼ð Þ β ð Þ md ij yd ijv cos ; 43b
ð Þ ¼ð Þ β ð Þ mu ij yu ijv sin ; 43c ð Þ ð Þ where mu;d;e ij and yu;d;e ij are the SM fermion mass and 2 2 Yukawa coupling matrices, respectively, and v ≡ vu þ 2 ≃ ð174 Þ2 vd GeV is the SM Higgs VEV. In the mass basis, these matrices are diagonal. Neglecting quark mixing (see Refs. [39,40] for a fuller treatment) the interaction basis coincides with the mass basis, resulting (given values for β Λ ð ð5Þ Þ tan and IR) in a system with 24 free parameters Ye;d;u ii and cLi;ei;Qi;di;ui and nine constraint equations following from (43). If we take a universal value for the 5D Yukawa ð ð5Þ Þ ¼ ð5Þ couplings such that Ye;d;u ii Y k, there remains one parameter degree of freedom within each generation of leptons and within each generation of quarks, which we choose as the doublet c parameters cLi;Qi , without loss of generality. The relations (43) hold for the running masses. Ultimately, we are interested in the bulk mass parameters at the IR-brane FIG. 6. Contours of the effective 4D Yukawa coupling (42) at scale, where they determine the soft masses received by the the IR-brane scale as a function of the localization parameters cL sfermions when supersymmetry is broken. Therefore, before and cR of the bulk fermion fields for tan β ¼ 3, ΛIR ¼ we perform the 4D-5D Yukawa matching, we first evolve the 2 × 1016 GeV, and Yð5Þk ¼ 1. The dashed gray lines give 4D Yukawa couplings to the IR-brane scale. We discuss the contours of the Yukawa coupling strength. In color are contour procedure we use to consistently perform the renormaliza- lines corresponding to the coupling strengths of the SM Yukawa tion in Sec. IV B 1.InFig.6, we give an example of the couplings at the IR-brane scale. The region in which each field is resulting matching, showing the allowed range of local- IR localized is shaded light gray and the region where both fields izations (c parameters) of the SM leptons and quarks when are IR-localized is darker gray. the 5D Yukawa coupling takes the universal value Yð5Þk ¼ 1 Λ ¼2 1016 and IR × GeV. Generally, we see that the largeness include Yukawa couplings for the neutrinos. Neutrinos can of the third-generation Yukawa couplings requires the be naturally incorporated in a warped extra dimension to third-generation fermions for both leptons and quarks to generate the required neutrino masses [24,41–44]. be UV-localized (white region), while the smaller Yukawa couplings of the first and second generations lead to IR C. Supersymmetry breaking localization (darker gray region). Although it is always Supersymmetry is assumed to be broken on the IR brane possible to make one of the chiral fermions in each and is parametrized by the introduction of a spurion generation UV-localized, only for the third generation can superfield X ¼ θθF that couples to the sfermions and this be done without making at least one of the other chiral X the gauginos. The sfermions and gauginos acquire tree- fermions IR localized. level soft masses with a characteristic scale F=Λ , where We note in passing that in the quark sector, since both IR F ¼ F e−2πkR, modulated by their overlap with the IR singlet fields in a given generation must be separately X brane. A gravitino mass of order F=M is generated by the matched to the same doublet field according to (42), the P super-Higgs effect. The Higgs fields receive no tree-level asymmetry between the 4D couplings yui and ydi precludes ð5Þ ð5Þ soft masses, as they are confined to the UV brane and do the solution c ¼ −c ¼ −c unless y =y ¼ Yu =Y . Qi di ui ui di i di not couple directly to the supersymmetry-breaking spurion. In this case, the 4D Yukawa coupling hierarchies are simply We do not include any mechanism to generate tree-level moved into the 5D couplings. This behavior is an indication trilinear soft scalar couplings, although, like the Higgs- of the universality of the warped extra dimension: while it sector soft terms, they arise radiatively. can explain the magnitude of the Yukawa coupling hier- Contributions to the soft masses also generically arise archies, since it is flavor-blind, the underlying flavor from anomaly mediation. Since the gravitino mass is structure remains as an order-one feature. In practice, we Planck-scale suppressed (as opposed to the other soft take Yð5Þk to have a universal value and absorb the flavor masses, which are suppressed by the IR-brane scale), the structure completely into the quark c parameters. A similar anomaly-mediated contribution typically is subdominant situation does not arise in the lepton sector as we do not to the effects (both at tree level and loop level) of the
035046-12 PARTIALLY COMPOSITE SUPERSYMMETRY PHYS. REV. D 99, 035046 (2019) supersymmetry-breaking sector on the IR brane. An addi- 2. Gaugino masses tional source of supersymmetry breaking arises due to the For a field strength superfield Wa of a vector super- stabilization of the radion of the extra dimension, which a a multiplet V containing a standard model gauge field Aμ generically requires a nonzero F-term for the radion and its Majorana fermion gaugino superpartner λa (where a superfield (equivalently, the introduction of a constant is the gauge index), we introduce the interaction superpotential on the IR brane). The scale of the radion- Z Z mediated contribution to the soft masses depends on the pffiffiffiffiffiffi 1 5 2 X αa a S5 ¼ d x −g d θ W Wα þ H:c: δðy −πRÞ: details of the stabilization model. We are interested in the 2Λ k regime where such effects are subdominant to the effects UV ð Þ of the supersymmetry-breaking sector on the IR brane. In 47 the model of Ref. [36], this can be accomplished if the Goldberger-Wise bulk hypermultiplet is sufficiently UV This term gives rise to a boundary Majorana mass for the localized. gaugino field and breaks supersymmetry, shifting the masses of the Kaluza-Klein modes up such that there is no longer a massless gaugino zero-mode solution. At tree 1. Gravitino mass level, the lightest KK mass is
When supersymmetry is spontaneously broken on the IR 2 g5k F 2 F boundary, the effective 4D cosmological constant receives a Mλ ≃ ¼ g ; ð48Þ 2πkR Λ Λ positive contribution from the VEV of FX. In the 5D IR IR warped geometry, this contribution can be canceled by the where g2k ¼ð2πkRÞg2. This mass expression (48) assumes addition of a constant superpotential W on the UV brane 5 the zero-mode approximation for the profiles, where the [36,45–50], which introduces a boundary mass term for the back reaction of the boundary Majorana mass is neglected, gravitino: pffiffiffiffi an approximation that is valid provided F=Λ ≲ 1.In Z pffiffiffiffi IR practice, we include terms higher order in F=Λ . The 5 pffiffiffiffiffiffi 1 W μ ν IR S5 ¼ d x −g ψ μ½σ ; σ¯ ψ ν þ H:c: δðyÞ: ð44Þ mass for arbitrary F can be determined by solving the full 4 M3 5 KK mass quantization condition (see Refs. [17,25]). Note Λ that the gaugino masses are suppressed relative to F= IR by The cosmological constant vanishes when 2 2 6 g ∼ g5=πkR, the square of the 4D gauge coupling [49], and hence the gauginos in general obtain masses suppressed jWj2 jFj2 ≃ 3 ; ð45Þ below those of sfermions with flat profiles ( c ¼ 1). This M2 2 P suppression matches that found in (26), as expected from the AdS=CFT dictionary. such that the lightest gravitino obtains a Majorana mass: If the supersymmetry-breaking sector does not contain any singlets with large F-terms, the interaction (47) is F m3 2 ≃ pffiffiffi : ð46Þ forbidden. In this case, with a nonsinglet spurion X, the = 3 MP leading contribution to the gaugino masses is [51] Z Z This is the super-Higgs effect.5 Again, higher-order terms pffiffiffiffiffiffi 1 † 5 4 X X αa a S5 ¼ d x −g d θ W Wα þ H:c: δðy −πRÞ; can be included to account for the back reaction of the 2Λ3 k gravitino boundary mass, although in practice this is not UV ð Þ necessary in the relevant regions of our parameter space. As 49 expected, due to the universality of gravity, this matches the such that usual 4D result. Since the gravitational coupling is Planck- scale suppressed, the gravitino mass is lower than the 2 2 2 Λ g5k F 2 F characteristic soft mass scale F= IR by a warp factor, and Mλ ≃ ¼ g : ð Þ 2π Λ3 Λ3 50 the gravitino is therefore always the LSP in the relevant kR IR IR regions of parameter space. This is consistent with the pffiffiffiffi ∼ Λ partial compositeness result (31) in the 4D dual theory, Except in the regime F IR, this mass is highly sup- where the gravitino is mostly an elementary state. pressed, and other supersymmetry-breaking contributions such as radion mediation may dominate. 5Note that a constant superpotential can also be introduced on the IR brane, as is generically expected in the context of radion 6The gauge-coupling dependence arises since we assume a stabilization. However, such a superpotential provides a positive generic GUT symmetry that is broken by the Higgs mechanism contribution to the cosmological constant, and so it cannot be the on the UV brane, separated from the supersymmetry-breaking sole source for the gravitino mass. sector on the IR boundary.
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3. Sfermion masses For a chiral supermultiplet Φ containing a Weyl fermion ψ and its complex scalar superpartner ϕ, we introduce the interaction
Z Z † 5 pffiffiffiffiffiffi 4 X X † S5 ⊃ d x −g d θ Φ Φδðy − πRÞ: ð Þ Λ2 51 UVk
As with the gauginos, adding this boundary mass breaks supersymmetry. At tree level, the lightest KK mass is sffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffi 1 ∓ F 2 c ð1∓ Þπ tree ≃ 2 c kR mϕ 2ð1∓ Þπ e L;R Λ 2 c kR − 1 IR e FIG. 7. Plot of the magnitude of the tree-level scalar soft 8 > 1 1=2 ð1∓ Þπ 1 mass and the gauge and Yukawa one-loop radiative corrections as <> − F 2 c kR c 2 Λ e c>2 ; a function of hypermultiplet localization when the gauginopffiffiffiffi ∼ IR ð Þ Λ ¼ 2 1016 ¼ 1 2 52 masses are given by (48). We take IR × GeV, F > 1 = F 1 10 : ∓ c c< ; 4.75 × 10 GeV, and tan β ¼ 3. 2 ΛIR 2 where the upper (lower) signs refer to the L (R) states. As pwithffiffiffiffi the gauginos, the scalar mass is valid in the limit Λ ≲ 1 F= IR , and in our numerical calculations we include Λ2 terms higher order in F= IR to account for the back reaction of the sfermion boundary mass. For simplicitly, we have taken these interactions to be flavor-diagonal, although this assumption can be relaxed. Note that the 1 UV-localized ð c>2Þ sfermion masses are suppressed by a warp factor relative to the IR-localized sfermion 1 masses ð c<2Þ because supersymmetry is broken on the IR brane. This behavior is illustrated in Figs. 7 and 8. Λ Λ ¼ −πkR δ ¼j 1 j Using the relations IR= UV e and i ci 2 , the expressions (52) are seen to be consistent with the FIG. 8. Plot of the magnitude of the tree-level scalar soft mass masses (23) obtained in the 4D dual theory. and the gauge and Yukawa one-loop radiative corrections as a Since the soft masses generated at tree level by (51) can function of hypermultiplet localization when thepffiffiffiffi gaugino masses 6 6 be exponentially small for UV-localized bulk scalar fields, are given by (50). We take ΛIR ¼6.5×10 GeV, F¼2×10 GeV, quantum corrections become significant when c is and tan β ¼ 5. sufficiently large. At the one-loop level, supersymmetry breaking is transmitted to the bulk scalars via interactions with other bulk scalars and gauginos. In Appendix C1,we masses squared at the IR-brane scale, arising when the KK derive the resulting contributions to the bulk scalar masses modes of the theory are integrated out. Parametrized in squared in the bulk theory. From the 4D perspective, these terms of the gaugino and sfermion tree-level soft masses, appear as one-loop threshold corrections to the scalar soft the corrections take the forms
32 ˜ ˜ 2 ˜ ˜ ˜ 1 16π2ðΔ 2 Þ ¼ Qi 2 2 þ 6 Qi 2 2 þ Qi 2 2 − 2 Qi 2 2 − 2 Qi 2 2 − 2Δ ð Þ m ˜ 1-loop rg3 g3M3 rg2 g2M2 rg1 g1M1 ryu yu mu˜ ryd y m˜ g1 S; 53a Qi 3 15 i i i i di di 5
32 ˜ 32 ˜ ˜ 4 16π2ðΔ 2 Þ ¼ ui 2 2 þ ui 2 2 − 4 ui 2 2 þ 2Δ ð Þ mu˜ 1-loop rg3 g3M3 rg1 g1M1 ryu yu m ˜ g1 S; 53b i 3 15 i i Qi 5
32 ˜ 8 ˜ ˜ 2 16π2ðΔ 2 Þ ¼ di 2 2 þ di 2 2 − 4 di 2 2 − 2Δ ð Þ m˜ 1-loop rg3 g3M3 rg1 g1M1 ryd yd m ˜ g1 S; 53c di 3 15 i i Qi 5
˜ 6 ˜ ˜ 3 16π2ðΔ 2 Þ ¼ 6 Li 2 2 þ Li 2 2 − Li 2 2 þ 2Δ ð Þ m ˜ 1-loop rg2 g2M2 rg1 g1M1 rye ye me˜ g1 S; 53d Li 5 i i i 5
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24 ˜ ˜ 6 16π2ðΔ 2 Þ ¼ ei 2 2 − 4 ei 2 2 − 2Δ ð Þ me˜ 1-loop rg1 g1M1 rye ye m ˜ g1 S; 53e i 5 i i Li 5 where ΔS, defined in (C22),is X h i Δ ¼ ðϕ Þ D 2 ¼ D 2 − 2 D 2 þ D 2 − D 2 þ D 2 ð Þ S Y i rϕ mϕ Tr r ˜ m ˜ ru˜ mu˜ r˜ m˜ r ˜ m ˜ re˜ me˜ ; 54 i i Qi Qi i i di di Li Li i i i
ϕi ϕi and the sum is over the sfermions. The coefficients rg , ry , with the inclusion of D-term and Yukawa radiative con- and rD , defined in (C7), (C14), and (C23), respectively, are tributions. The moderate size of this hierarchy is an ϕi numerical parameters which encode the effect of the extra important result of the inclusion of radiative corrections, dimension. which wash out the exponential localization dependence of The radiative corrections to the bulk scalar soft masses the sfermion soft masses that is a tree-level feature of the can be divided into three types of contributions: gauge extra dimension. corrections arising from loops involving bulk vector super- A larger hierarchy can be achieved if the supersymmetry- multiplets, Yukawa corrections arising from loops of bulk breaking sector does not contain any singlets with large hypermultiplets and boundary Higgs fields, and D-term F-terms as in Fig. 8. In this case, the gaugino masses take corrections arising from the Fayet-Iliopoulos D-term for the form (50), and the characteristic sfermion hierarchy is UV IR ∼ 2 Λ weak hypercharge. In Fig. 7 we plot the magnitudes of the mϕ =mϕ gaF= IR. The maximum splitting that can be various contributions as functions of the hypermultiplet accommodated between the two sfermion mass scales is localization when the gaugino mass is given by (48) limited by the requirement that no sfermions receive (singlet spurion), and the magnitudes when the supersym- negative soft masses at the IR-brane scale or in the metry-breaking sector does not contain any singlets with subsequent RG evolution of the theory to lower scales. large F-terms and the gaugino mass takes the form (50) in The constraints this condition imposes on the pattern of Fig. 8. In each case, the tree-level sfermion mass is plotted sfermion mass spectrum at the IR-brane scale are discussed in grey, the one-loop U(1), SU(2), and SU(3) gauge in Sec. IVA 2. radiative corrections are plotted in green, and the magni- In the sfermion sector, localization in the extra dimen- tude of the maximal contribution from a single Yukawa sion thus distinguishes between two scales: a tree-level 1 1 coupling (this corresponds to cL ¼ 2 or −cR ¼ 2 for the mass scale associated with IR-localized sfermions and a corresponding doublet and singlet hypermultiplets), lower mass scale arising from radiative corrections for UV- neglecting all color multiplicity factors and modulo the localized sfermions. When the localizations of the matter 5D Yukawa coupling, is plotted in orange. Also shown is hypermultiplets are chosen to explain the SM fermion mass the magnitude of the one-loop D-term radiative contribu- hierarchy (i.e., the third-generation fermions must be tion due to a single scalar mode (yellow), modulo hyper- predominantly UV-localized, while the lighter generations charge factors.7 are mostly IR-localized), the result is a split sfermion Due to the conformal flatness of the vector supermul- spectrum, with the third-generation sfermions hierarchi- tiplet, the gauge corrections take a universal value for cally lighter than the first two generations. We note that the UV-localized sfermions that is of order of the gaugino sfermion spectrum inverts the ordering of the fermion masses. These contributions are positive and set the spectrum, a consequence of the separation of the super- characteristic scale of the radiative corrections. Since the symmetry-breaking sector and the Higgs sector on opposite tree-level contribution is dominant for IR-localized sfer- orbifold fixed points. Additionally, although both are mions, which accordingly receivepffiffiffiffi a mass of order of the explained by the same localization mechanism, the sfer- Λ characteristic soft mass scale F= IR, the sfermion sector mion hierarchy is necessarily less split than the fermion UV IR ∼ Λ thus accommodates a hierarchy mϕ =mϕ Ma IR=F. hierarchy. This is because the Yukawa couplings only When the gaugino mass is given by (48) as in Fig. 7, receive wave function renormalization, while the scalar UV IR 2 masses are soft parameters and can receive large radiatve the sfermion hierarchy is mϕ =mϕ ∼ ga ∼ Oð0.4 − 1Þ, which may be increased modestly in individual families corrections from the extra dimension and MSSM running.
7As seen in Appendix C1c, one-loop D-term corrections are 4. Higgs sector independent of the localization of the external scalar, and so here The Higgs sector, confined to the UV brane, does not we plot the contribution as a function of the localization of the scalar contributing in the loop (unlike the other radiative con- couple directly to the supersymmetry-breaking sector, and tributions, which depend on the localization of the external thus the Higgs soft terms at the IR-brane scale are zero at scalar). tree level. Nevertheless, as with the sfermions, the breaking
035046-15 BUYUKDAG, GHERGHETTA, and MILLER PHYS. REV. D 99, 035046 (2019) is transmitted to the Higgs fields at the quantum level. We derive the one-loop corrections to m2 , m2 , and b from the Hu Hd bulk theory in Appendix C2. Parametrized in terms of the tree-level gaugino and sfermion soft masses, the one-loop Higgs masses take the form
6 16π2 2 ¼ 6 H 2 2 þ H 2 2 m rg2 g2M2 rg1 g1M1 Hu 5 3 − 6 ½ H 2 ð 2 þ 2 Þ − 2Δ ð Þ Tr ry yu m ˜ mu˜ g1 S; 55a ui i Qi i 5
6 16π2 2 ¼ 6 H 2 2 þ H 2 2 −6 ½ H 2 ð 2 þ 2 Þ mH rg2 g2M2 rg1 g1M1 Tr ry y m ˜ m˜ d 5 di di Qi di 3 FIG. 9. Plot of the magnitude of the one-loop radiative −2 ½ H 2 ð 2 þ 2 Þ þ 2Δ ð Þ Tr ry ye m ˜ me˜ g1 S; 55b corrections that generate the Higgs soft masses as a function ei i Li i 5 of hypermultiplet localizationpffiffiffiffi in the singlet spurion case. We take Λ ¼ 2 × 1016 GeV, F ¼ 4.75 × 1010 GeV, and tan β ¼ 3. 6 IR 2 b 2 b 2 16π b ¼ −μ 6r g2M2 þ r g1M1 ; ð55cÞ λ1 5 λ2
H H b where rg , ry , and rλ are defined in (C29), (C34), and (C41), respectively. The origin of the μ-term on the UV brane is assumed to arise from the Kim-Nilles mechanism, as discussed in Sec. II D; its magnitude is determined as necessary to ensure that electroweak symmetry is broken, along with the value of tan β, as described in Sec. III D. In Figs. 9 and 10, we plot the magnitudes of the various one-loop contributions to the Higgs soft masses as func- tions of hypermultiplet localization in the singlet spurion and nonsinglet spurion cases, respectively. The U(1) (lighter green) and SU(2) (darker green) gauge-sector contributions are independent of localization. In orange, we give the maximal contribution from a single Yukawa ¼ 1 − ¼ 1 FIG. 10. Plot of the magnitude of the one-loop radiative coupling (this corresponds to cL 2 or cR 2 for the corrections that generate the Higgs soft masses as a function corresponding doublet and singlet hypermultiplets), of hypermultiplet localizationp inffiffiffiffi the nonsinglet spurion case. We Λ ¼ 6 5 106 ¼ 2 106 β ¼ 5 neglecting all color multiplicity factors and modulo the take IR . × GeV, F × GeV, and tan . 5D Yukawa coupling. These contributions are negative. In yellow is the D-term contribution from a single bulk scalar, modulo the scalar hypercharge. These individual contribu- 5. Trilinear soft scalar couplings (a-terms) tions can be either positive or negative depending on the Soft a-terms are also generated radiatively. We derive the relative sign between the hypercharge of the Higgs field one-loop corrections in Appendix C4. Parametrized in terms and the hypercharge of the scalar. of the tree-level gaugino masses, these take the forms:
32 2 8 8 2 a 2 a 2 a a a 2 16π a ¼ −y ðrλ Þ g3M3 þ 6ðrλ Þ g2M2 þ − ðrλ Þ þ ðrλ Þ þ ðrλ Þ g1M1 ; ð56aÞ ui ui 3 3 Qiui 2 Qi 5 1 Qi 5 1 ui 15 1 Qiui 32 2 4 4 2 a 2 a 2 a a a 2 16π a ¼ −y ðrλ Þ g3M3 þ 3ðrλ Þ g2M2 þ ðrλ Þ þ ðrλ Þ − ðrλ Þ g1M1 ; ð56bÞ di di 3 3 Qidi 2 Qi 5 1 Qi 5 1 di 15 1 Qidi 6 12 12 2 a 2 a a a 2 16π a ¼ −y 6ðrλ Þ g2M2 þ − ðrλ Þ þ ðrλ Þ þ ðrλ Þ g1M1 ; ð56cÞ ei ei 2 Li 5 1 Li 5 1 ei 5 1 Liei
a where the rλ are defined in (C46a) and (C46b).
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D. Electroweak symmetry breaking model is in general quite large. The overall mass scale of Λ In the MSSM, the tree-level scalar potential has a our sparticle spectrum isp jointlyffiffiffiffi determined by IR, the minimum breaking electroweak symmetry if the following scale of the IR brane, and F, the scale of supersymmetry two equations are satisfied: breaking. Together these two parameters fill the roles associated with MGUT, m1=2, and m0 in classic universal 2 2 1 2 2 2 supergravity (SUGRA) models. As we discuss in Sec. III D, m þjμj − b cot β − ðg1 þ g2Þv cos 2β ¼ 0; ð57aÞ Hu 8 we do not have the usual freedom in tan β and the sign of μ, which are in this case determined by electroweak symmetry 1 2 þjμj2 − β þ ð 2 þ 2Þ 2 2β ¼ 0 ð Þ breaking. In addition to these universal parameters, our mH b tan g1 g2 v cos : 57b d 8 model features nonuniversal IR-scale boundary conditions 2 2 for the sfermion soft masses, which we specify in a flavor- In our model, m , m , and b,givenby(55a), (55b), Hu Hd dependent way by choosing field localizations to explain and (55c), respectivelt, are radiatively generated at the IR- the SM fermion mass spectrum, as described in Sec. III B. brane scale when the extra dimension is integrated out. ð5Þ Solving (57) determines two parameters: the magnitude of We choose a universal value Y k for all 5D Yukawa the Higgsino mass parameter jμj and the ratio of Higgs couplings, such that this specification requires fixing six VEVs tan β. In the limit that the scale of supersymmetry additional free parameters, which we take as the doublet c parameters c and c . In this section we discuss various breaking is much larger than the scale of electroweak Li Qi symmetry breaking the physical solutions are phenomenological and theoretical constraints that impose qffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffi limits on the set of model parameters. 2 2 2 2 2 2 ðm − m Þþ ðm − m Þ þ 4b 2 Hd Hu Hd Hu v tan β ≃ þ O ; 1. Phenomenological considerations 2b b ð Þ We first consider five phenomenological desiderata that 58a constrain our model. (1) Gravitino dark matter.—Since the gravitino mass is m2 − m2 tan2 β jμj2 ≃ Hd Hu þ Oð 2Þ ð Þ Planck-scale suppressed, it is the LSP throughout 2 v ; 58b tan β − 1 our parameter space. In the absence of R-parity violation, the LSP is absolutely stable, and as such, where we require signðμÞ¼−1 and m2 < minðm2 ;m2 = Hu Hd Hd the gravitino makes an attractive dark matter can- tan2 βÞ. Solutions with signðμÞ¼þ1 are excluded at tree didate. However, the stability of a gravitino LSP can level since b is constrained to have the opposite sign from μ lead to cosmological problems, as the thermal at the IR-brane scale according to (55c) (and this typically gravitino mass density arising from freeze-out is remains true under RG evolution). Although these equa- sufficient to overclose the universe unless the grav- tions are modified when loop corrections to the Higgs itino is very light ½Oð100Þ eV [52,53]. In this case, scalar potential are included, they remain practical con- observations of the matter power spectrum at small straints since the iterative method employed to determine cosmological scales limit the free-streaming length electroweak symmetry breaking (EWSB) in the numerical of the gravitino, further requiring m3=2 < 4.7 eV in renormalization procedure (see Sec. IV B 1) requires an order for the gravitino to be adequately cold [54], initial tree-level solution. It is not guaranteed that the Higgs and gravitinos in this scenario cannot therefore soft terms (55a), (55b), and (55c) permit a tree-level account for all of the observed dark matter density. solution at the IR-brane scale, in which case electroweak Throughout the relevant parameter space of our symmetry must be broken radiatively. model, the gravitino is sufficiently heavy that we The conditions (58) for EWSB strongly favor m2 < 0. require inflation to dilute the initial thermal pop- Hu In order for this to occur, the combined radiative correc- ulation [55] and must restrict the reheating temper- tions to m2 both from the KK modes at the IR-brane scale ature so that the gravitino does not subsquently Hu and from the MSSM running to lower scales must be come back into thermal equilibrium. In this case, overall negative. We discuss the constraints this imposes on structure-formation constraints are weaker, requir- ≳ Oð1Þ the parameter space of our theory in Sec. IVA 2. ing m3=2 keV for generic warm dark matter candidates [56–58], such the gravitino may be the IV. SUPERPARTNER MASS SPECTRUM dominant component of dark matter. In this sce- nario, gravitinos may still be produced from the A. Model parameter space scattering of particles in thermal equilibrium with As we have seen in generating the fermion mass the plasma. The largest contribution arises from hierarchy and breaking supersymmetry, the parameter gluinos, such that the thermal gravitino density space available for our partially composite supersymmetric takes the form
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pffiffiffiffi Λ FIG. 11. Plot of the gravitino dark matter constraints on the parameter space of our model in the ( IR; F) plane in the singlet spurion case for Yð5Þk ¼ 1. 2 100 GeV m˜ T component of dark matter. If nonthermal production Ωthermal 2 ∼0 3 g R 3=2 h . 10 : is significant, the reheating temperature must be m3=2 1 TeV 10 GeV lowered to suppress the contribution from thermal ð59Þ production. In the hatched yellow regions, the thermal relic density is insufficient to provide all For m3=2 ≲ 1 keV, thermal scattering production of of the dark matter, and some level of nonthermal gravitinos cannot supply all of the observed dark production is required to obtain the observed dark matter density unless TR is high enough to bring matter density. the gravitino into thermal equilibrium. Further parameter space constraints arise from big Gravitinos are also produced nonthermally, bang nucleosynthesis (BBN), which strongly limits via decays of the next-to-lightest supersymmetric the NLSP energy density if the NLSP is long-lived particle (NLSP), which in our model is typically enough to decay to the gravitino during or after the either a (Bino-like or Higgsino-like) neutralino or a (mainly right-handed) stau. In both cases, the NLSP is sufficiently long-lived throughout our parameter space to decay after freeze-out, such that the resulting nonthermal gravitino population takes the form (superWIMP scenario [59]):
m3 2 Ωnonthermal 2 ¼ = Ω 2 ð Þ 3=2 h NLSPh : 60 mNLSP The initial NLSP population that contributes to Ω 2 NLSPh is moderated by TR. In particular, if the reheating temperature is low enough that the NLSP never comes into thermal equilibrium after infla- ≲ 20 tion (TR mNLSP= ), the initial NLSP population is Boltzmann-suppressed. Ω 2 ¼ The observed dark matter abundance ( dmh 0.1186 0.0020 [60]) thus places an upper limit on the reheating temperature. We showpffiffiffiffi an estimate ðΛ Þ of these limits in the space of IR; F in Figs. 11 and 12. In each case, the yellow contours give the FIG. 12. Plot of the gravitino dark matterp constraintsffiffiffiffi on the Λ reheating temperature necessary for the thermal parameter space of our model in the ( IR; F) plane in the gravitino relic density (59) to provide the dominant nonsinglet spurion case for Yð5Þk ¼ 1.
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formation of the light elements. To avoid altering the flavor-changing neutral currents (FCNCs) and successful predictions of the standard BBN scenario, CP-violation at levels above current experimental decays to the gravitino must be prompt, limiting the limits. This problem can be alleviated if the sfermions τ Oð0 1 − 100Þ lifetime of the NLSP to NLSP < . s, or, of the first and second generations are heavy, ≪ for m3=2 mNLSP, Oð100Þ TeV [63–66], or even heavier [67–69],a 2 5 solution that has gained popularity in the absence of m3 2 = Oð1 − 4Þ = ð Þ any low-energy experimental signatures of supersym- mNLSP > TeV ; 61 10 GeV metry. Such a solution is a natural and elegant choice in our model, as the inverted hierarchy in the sfermion as a conservative estimate. This condition places pffiffiffiffi soft mass spectrum naturally separates the scale of the constraints in the space of Λ and F. We show the IR first two generations from that of the third, which can regions where τ < 0.1 s in the neutralino NLSP remain light enough to explain the Higgs mass and case (dark orange) and in stau case (magenta) in offer the possibility of experimental detection. Figs. 11 and 12. Evading these limits restricts the Thus, to ameliorate the flavor problem, we restrict reheating temperature for our model to the range the masses of the first- and second-generation sfer- T ∼ Oð102–106Þ GeV, necessitating an alterna- R mions to be at least 100 TeV. As a constraint, this tive to thermal leptogenesis to generate the baryon condition places an upper (lower) limit on the asymmetry. c parameters of the first- and second-generation If the NLSP is the stau and is sufficiently stable to left-handed (right-handed) bulk hypermultiplet fields. survive into BBN, the formation of bound states with nuclei can catalyze the production of light elements This is a further limit on the hypermultiplet local- 3 3 izations beyond the structure necessary to explain the [61]. In particular, if 10 s ≲ ττ˜ ≲ 5 × 10 s, the 1 SM fermion mass spectrum. In Figs. 13 and 14,we catalytic enhancement for 6Li can solve the lithium showp anffiffiffiffi estimate of the region in the space of problem in the standard BBN scenario [62]. We show ðΛ Þ an estimate of the region in which the stau lifetime IR; F where this limit is incompatible with the falls within these limits in teal in Fig. 11. We note SM fermion mass for at least one field (the strictest however, that this solution to the lithium problem is constraint typically comes from the muon, the heaviest ruled out for our model, as the entirety of the catalytic of the first- and second-generation fermions). — region is excludedby currentLHC limits (see Fig. 13). (3) 125 GeV Higgs mass and collider exclusion limits. In the nonsinglet spurion case, the stau is not In the MSSM, the tree-level mass of the neutral scalar Higgs boson is bounded from above by sufficiently long-lived to survive into BBN anywhere tree in the relevant parameter space. mh