Light Charginos.Pdf

CHARGED FERMIONS BELOW 100 GEV 1801.04432 Daniel Egana-Ugrinovic C.N. Yang Institute, Stony Brook University

Matthew Low Institute for Advanced Study

Joshua Ruderman New York University

SUSY 2018, Barcelona. 1 FERMIONS WITH UNIT ELECTRIC CHARGE

Are motivated by naturalness, theories of dark matter and baryogenesis.

Are being intensely looked for at LHC, mostly in the form of “charginos”.

LHC chargino mass reach as high as ~1 TeV.

But we have to be careful…

Are we leaving gaps at low masses?

2 Daniel Egana-Ugrinovic, C.N. Yang Institute, Stony Brook University THERE IS A 100 GEV “FOLK" BOUND

From R. Camacho’s talk Atlas 1403.5294 From the PDG “LEP limit is 103 .5GeV ” 0 “For m(1± ,1) 3GeV limit degrades to 91.9GeV ”  3 Daniel Egana-Ugrinovic, C.N. Yang Institute, Stony Brook University SIMPLE MESSAGES TO TAKE AWAY

Fermions with unit electric charge well below 100 GeV* are not ruled out by LEP or LHC.

* And above mZ/2

4 Daniel Egana-Ugrinovic, C.N. Yang Institute, Stony Brook University 0 0 the chargino, H± , and the neutralino, H . At dimension-ﬁve, the masses of H± and H may be split by the Weinberg operator (in the MSSM this mass splitting arises from the mixing

0 0 among the higgsinos,± winos, and bino). At one-loop, there is an additional± irreducible the chargino, H , and the neutralino, H0. At dimension-five, the masses of H and H0 may the chargino, H± , and the neutralino, H . At dimension-five, the masses of H± and H may contributionbe split to by the the mass Weinberg splitting operator from (in infrared the MSSM e↵ thisects. mass In splitting the range arises 50 from GeV the mixingm be split by the Weinberg operator (in the MSSM this mass splitting arises from the mixingH±  among the higgsinos, winos, and bino). At one-loop, there is an additional irreducible 100 GeV, thisamong radiative the higgsinos, splitting winos, monotonically and bino). At increases one-loop, from there 206 is MeV an additional to 256 MeV irreducible [61]. In ARCHAEOLOGICALcontribution to the mass splitting from infrared COLLIDER e↵ects. In the rangePHYSICS 50 GeV m(ACP) H± this work,contribution we assume to that the the mass neutral splitting fermion from infrared is the e lightest↵ects. In component the range 50 of GeV the doubletm  and 100 GeV, this radiative splitting monotonically increases from 206 MeV to 256 MeV [61].H± In is stable. 100 GeV, this radiative splitting monotonically increases from 206 MeV to 256 MeV [61]. In this work, we assume that the neutral fermion is the lightest component of the doublet and At LEP,thisConcentrate charginos work, we assume are pairon that producedcharged the neutral viaHiggsinos fermions-channel is the (SU(2) diagrams lightest componentdoublets) mediated of the by doublet gauge bosons and is stable. is stable. and they decayAt LEP, through charginosW arebosons pair produced into quarks, via s-channel leptons diagrams or pions, mediated as shown by gaugein Fig. bosons3. The LEPI:At LEP, irreducible charginos are bound pair produced via s-channel diagrams mediated by gauge bosons decays may be two or three-body, depending on the chargino-neutralino mass splitting. Since andand they they decay decay through throughWWbosonsbosons into into quarks, quarks, leptons leptons or or pions, pions, as as shown shown in in Fig. Fig. 33.. The The all interactionsdecaysdecays may are may be fixed be two two or by or three-body, the three-body, higgsino’s depending depending quantum on on the the numbers, chargino-neutralino chargino-neutralino the properties mass mass splitting. splitting. of the higgsino Since Since all interactions are fixed by the higgsino’sm quantum± m numbers,Z /2 the properties of the higgsino system, includingall interactions the chargino are fixed lifetimeby the higgsino’s and branchingH quantum ratios,numbers, are the completely properties of determined the higgsino by the charginosystem,system, and including including neutralino the the chargino masses. chargino lifetime lifetime and and branching branching ratios, ratios, are are completely completely determined determined by thetheLEP chargino chargino II: presumably and and neutralino neutralino masses.covers masses. the chargino mass region 45-100 GeV ¯ f¯d ffd¯ + + d e + H ++ +( ) e + H + e , Z H W +(⇤+() ) ++⇡ ,Z, Z WW ⇤⇤ ⇡⇡ + ffu + ++ fuu ++ H HH HHH 0 00 00 0 e ee H HH HHH HHH

Figure 3:FigureFigureFeynman 3: 3:FeynmanRatesFeynman diagrams fixed diagrams diagrams for by chargedchargino-neutralino for for charged charged higgsino higgsino higgsino pair pair pair productionmasses production production and at at gauge LEP LEP LEP (left) (left) (left)invariance and and and charged charged charged higgsinoshiggsinos decays decays (center (center and and right). right).fuf,fu,fd dstandstand for for Standard Standard Model Model up up or or down down type type quarks quarks higgsinos decays (center and right). fu,fd stand for Standard Model up or down type quarks 5 oror leptons. leptons. Both Both the the cross cross section section and and branching branching ratios ratios are are fixed fixed by by the the higgsino’s higgsino’s quantum quantum or leptons.Daniel Both Egana-Ugrinovic, the cross C.N. section Yang Institute, and branching Stony Brook ratiosUniversity are fixed by the higgsino’s quantum numbersnumbers and and the the chargino chargino and and neutralino neutralino masses. masses. numbers and the chargino and neutralino masses.

LEPLEP performed performed several several searches searches for for charged charged higgsinos higgsinos heavier heavier than than half half the theZZ bosonboson mass. mass. LEPThe performedThe searches searches several may may be be searches divided divided into for into di charged di↵erent↵erent categories higgsinos categories depending depending heavier than on on the the half chargino-neutralino chargino-neutralino the Z boson mass. The searchesmassmass splitting may splitting be divided into di↵erent categories depending on the chargino-neutralino 0 m m m0 , (1) m mH± m H, (1) mass splitting ⌘⌘ H± H whichwhich controls controls both both the the typical typical momentum momentum of of the the final final state state particles particles and and the the chargino chargino m m m0 , (1) ⌘ H± H lifetimelifetime [64 [64].]. The The region regionm>m>3GeViscoveredbyconventionalsearcheslookingfor3GeViscoveredbyconventionalsearcheslookingfor which controlscharginoscharginos both promptly promptly the typical decaying decaying momentum into into leptons leptons of and and the jets. jets. final For For state 320 320 MeV MeV particles<< m require a3GeViscoveredbyconventionalsearcheslookingfor a photon photon from from ISR ISR as as well well as as other other detector detector activity activity from from the

chargino’s decay products. For m⇡± < m<320 MeV the chargino lifetime is greater than charginoschargino’s promptly decay decaying products. into For leptonsm⇡± < andm< jets.320 MeV For the 320 chargino MeV lifetime< m< is greater3 GeV, than the 1cm,anddedicatedsearchesfordisappearingtracksandlargeimpactparametersset most e↵ective⇡1cm,anddedicatedsearchesfordisappearingtracksandlargeimpactparametersset searches require a photon from ISR as well as other detector activity from the ⇡ chargino’s decay products. For m⇡ < m<320 MeV the chargino lifetime is greater than ± 6 1cm,anddedicatedsearchesfordisappearingtracksandlargeimpactparametersset6 ⇡

6 0 0 the chargino, H± , and the neutralino, H . At dimension-ﬁve, the masses of H± and H may be split by the Weinberg operator (in the MSSM this mass splitting arises from the mixing among the higgsinos, winos, and bino). At one-loop, there is an additional irreducible contribution to the mass splitting from infrared e↵ects. In the range 50 GeV m  H±  100 GeV, this radiative splitting monotonically increases from 206 MeV to 256 MeV [61]. In this work, we assume that the neutral fermion is the lightest component of the doublet and is stable. At LEP, charginos are pair producedARCHAEOLOGICAL via s-channel diagrams mediated by gauge (LEP) bosons COLLIDER PHYSICS and they decay through W bosons into quarks, leptons or pions, as shown in Fig. 3. The decays may be two or three-body, dependingLEP on the II: chargino-neutralinodepending on the mass chargino-neutralino splitting. Since mass splitting, all interactions are ﬁxed by the higgsino’s quantum numbers, the properties of the higgsino system, including the chargino lifetime and branching ratios, are completely determined by 1. Conventional searches: m 5 GeV the chargino and neutralino masses. Prompt decays with hard leptons/jets f¯d + + e H +( ) + , Z W ⇤ II. Compressed⇡ region: m = O(1) GeV + fu + H H 0 0 e H H Prompt Hdecays with soft leptons/jets. ISR Assisted.

Figure 3: Feynman diagrams for charged higgsino pair production at LEP III. (left) Super-compressed and charged region: m 500 MeV higgsinos decays (center and right). fu,fd stand for Standard Model up or down type quarks  or leptons. Both the cross section and branching ratios are ﬁxed by the higgsino’sDisplaced quantum decays. Kinked tracks, numbers and the chargino and neutralino masses. HSCP, impact parameter offset. 6 Daniel Egana-Ugrinovic, C.N. Yang Institute, Stony Brook University LEP performed several searches for charged higgsinos heavier than half the Z boson mass. The searches may be divided into di↵erent categories depending on the chargino-neutralino mass splitting

m m m0 , (1) ⌘ H± H which controls both the typical momentum of the ﬁnal state particles and the chargino lifetime [64]. The region m>3GeViscoveredbyconventionalsearcheslookingfor charginos promptly decaying into leptons and jets. For 320 MeV < m<3 GeV, the most e↵ective searches require a photon from ISR as well as other detector activity from the chargino’s decay products. For m⇡± < m<320 MeV the chargino lifetime is greater than 1cm,anddedicatedsearchesfordisappearingtracksandlargeimpactparametersset ⇡

6 REVISITING LEP LIMITS ON PURE HIGGSINOS Uncompressed region Compressed region

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Pure higgsinos below ~90 GeV are indeed excluded.

Digitized OPAL and ADLO limits available on request 7 Daniel Egana-Ugrinovic, C.N. Yang Institute, Stony Brook University LOTS OF ASSUMPTIONS GOING INTO THAT LIMIT

1. The production cross section may be smaller if the production mechanism is not exactly the pure chargino one.

Examples: charginos with interfering sneutrinos, other gauge reps, simpliﬁed models.

2. Final state topologies may be different from the ones considered at LEP

Example : super-compressed region with signiﬁcant enhancement in the decay width.

8 Daniel Egana-Ugrinovic, C.N. Yang Institute, Stony Brook University A SIMPLIFIED MODEL WITH INTERFERENCE

A (non-SUSY) model with a “higgsino” and a scalar singlet

1 m2 S2 + m F F¯ +  L FS¯ + ⌘ (FH)(FH¯ c) 2 S F Le e 5 Yukawa “Chargino- with electron neutralino” and singlet mass splitting

Two important effects: 1. Changes the cross section. 2. Changes the decay widths

9 Daniel Egana-Ugrinovic, C.N. Yang Institute, Stony Brook University 1. INTERFERENCE IN THE PRODUCTION X-SEC

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Determined Maximal t-channel by gauge invariance interference dominated 10 Daniel Egana-Ugrinovic, C.N. Yang Institute, Stony Brook University 2. ADDITIONAL DECAY CHANNELS

F¯0 f¯d

+( ) + ( ) W ⇤ ⇡ S ⇤ fu F + F + F + ⌫e F¯0 F¯0 e+

Figure 7. Feynman diagrams for charged fermion F ± decays. fu,fd stand for Standard Model up or down type quarks or leptons. The decays through a W ⇤ (left) or the two body decays into ⇡± (center) are set by the fermion’sA new quantum decay numbers, channel while the is singlet-mediated open. decay width (right) is controlled byThis the coupling affects andbranching the scalar singletfractions mass m andS. In total the singlet-mediated width. diagram, 0 0 both F¯ ⌫e and F ⌫¯e ﬁnal states are possible.

11 Daniel Egana-Ugrinovic, C.N. Yang Institute, Stony Brook University

Figure 8. Charged fermion F ± decay branching fractions as a function of the coupling  for a mass splitting of m m 0 = 3 GeV (left), and as a function of the mass splitting for coupling F ± F

 =0.5 (right). In both cases, the charged fermion mass is mF ± = 75 GeV and the scalar singlet mass is mS = 110 GeV. Decays into the charged pion are matched to decays into up and down quarks at m =0.9 GeV. Decay widths are obtained from [63, 73].

The singlet-doublet model is a simpliﬁed version of the wino-bino-sneutrino system. In the MSSM with decoupled higgsinos, the lightest chargino is wino-like. At LEP, s- channel production proceeds via gauge-mediated diagrams, while the interfering t-channel diagram is mediated by the electron sneutrino. Destructive interference due to the sneutrino-mediated diagram modiﬁes the charged wino production rates at LEP, and weak- ens the limits. As an example, consider taking the bino, wino, and higgsino masses to be

M1 = 300 GeV, M2 = 95 GeV, and µ = 500 GeV, with tan =2. In this case, the

– 11 – ELECTRON-RICH DECAYS

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Efﬁciencies are altered with respect to the pure-chargino case

“Higgsino” lifetime is reduced

12 Daniel Egana-Ugrinovic, C.N. Yang Institute, Stony Brook University LEP LIMITS ON THIS “HIGGSINO” ARE MUCH WEAKER

Uncompressed region Compressed region ��

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The (robust) LEP limit on our charged fermions is around 73 GeV.

13 Daniel Egana-Ugrinovic, C.N. Yang Institute, Stony Brook University LHC SETS ADDITIONAL LIMITS

Recall mass-splitting interaction

c ⌘5(FH)(FH¯ )

Large mass splittings Higgs invisible decays h F 0F¯0 !

For mass splittings below ~300 MeV, decay length is order ~cm.

Disappearing track searches

14 Daniel Egana-Ugrinovic, C.N. Yang Institute, Stony Brook University 0 0 the chargino, H± , and the neutralino, H . At dimension-ﬁve, the masses of H± and H may be split by the Weinberg operator (in the MSSM this mass splitting arises from the mixing among the higgsinos, winos, and bino). At one-loop, there is an additional irreducible contribution to the mass splitting from infrared e↵ects. In the range 50 GeV m  H±  100 GeV, this radiative splitting monotonically increases from 206 MeV to 256 MeV [61]. In this work, we assume that the neutral fermion is the lightest component of the doublet and is stable. At LEP, charginos are pair produced via s-channel diagrams mediated by gauge bosons and they decay through W bosons into quarks, leptons or pions, as shown in Fig. 3. The decays may be two or three-body, depending on the chargino-neutralino mass splitting. Since all interactions are ﬁxed by the higgsino’s quantum numbers, the properties of the higgsino system, including the chargino lifetime and branching ratios, are completely determined by the chargino and neutralino masses.

f¯d + + e H +( ) + , Z W ⇤ ⇡ + fu + H H 0 0 e H H H

Figure 3: Feynman diagrams for charged higgsino pair production at LEP (left) and charged higgsinosLHC decays (center SETS and right). ADDITIONALfu,fd stand for Standard Model LIMITS up or down type quarks or leptons. Both the cross section and branching ratios are ﬁxed by the higgsino’s quantum numbers and the chargino and neutralino masses. For mass splittings below ~10 GeV

F 0

p F + , Z Soft `/j Monojets Soft `/j p F

F 0 Mass splittings below the pion mass are well covered by LEP HSCP LEP performedsearches. several searches for charged higgsinos heavier than half the Z boson mass. The searches may be divided into di↵erent categories depending on the chargino-neutralino LHC multilepton do not lead to stronger limits than the ones set 6 by LEP.

15 Daniel Egana-Ugrinovic, C.N. Yang Institute, Stony Brook University STATUS OF LHC AND LEP LIMITS Uncompressed region Compressed region ��

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LEP LEP+LHC m 10 GeV m 76 GeV m 100 GeV F ± F ± m 10 GeV m 73 GeV m 73 GeV  F ± F ±

16 Daniel Egana-Ugrinovic, C.N. Yang Institute, Stony Brook University CONCLUSIONS

Fermions with unit electric charge may still lie below 100 GeV in generic models (singlet interference, fermions with hypercharge, wino-sneutrino system?)

ATLAS/CMS still have interesting parameter space to cover below 100 GeV.

The unit-charge fermion 100 GeV limit serves as a target for future monojet searches.

17 Daniel Egana-Ugrinovic, C.N. Yang Institute, Stony Brook University ADVERTISEMENT

Spontaneous Flavor Violation (soon) Daniel Egana-Ugrinovic Sam Homiller Patrick Meade Stony Brook University

Asymmetric Star Formation (soon-ish) Jae Hyeok Chang Daniel Egana-Ugrinovic Rouven Essig Stony Brook University Chris Kouvaris CP3-Origins

18 Daniel Egana-Ugrinovic, C.N. Yang Institute, Stony Brook University