JHEP05(2014)106 ′ Z m , and t m st review 2 Springer < May 22, 2014 March 5, 2014 April 24, 2014 April 28, 2014 boson ′ : : : : Z ′ process at 8TeV m ¯ t Z t measurements. We → Revised Received Published boson existing in eight Accepted Zjj ′ pp 10.1007/JHEP05(2014)106 Using existing UA2 con- ight scenarios is excluded Z se where riate kinematical cuts. We cance as a function of LHC machine. and doi: tical Physics, a boson that subsequently decays ′ W jj round events. We find constraints [email protected] Z , s, Published for SISSA by . Most scenarios have a lower bound of 1 − , at the LHC to explore the constraints in bγ ¯ b and Kei Yagyu d → γ ′ based upon the LHC data of Z ′ -inspired leptophobic Z 6 [email protected] → m , E pp mass ′ Z Takaaki Nomura . 3 a,b,c grand unified theory, differing in particle embeddings. We fir 6 1402.5579 E The Authors. c Phenomenological Models, Hadronic Colliders

We study collider phenomenology of a leptophobic , [email protected] E-mail: Taipei, Taiwan 11529, R.O.C. Physics Division, National CenterHsinchu, for Taiwan Theoretical 30013, Science R.O.C. Department of Physics, National1, Cheng Ta-Hsueh Kung Road, University, Tainan, Taiwan 70101, R.O.C. Department of Physics andNational Center Central for University, Mathematics Chungli, and TaiwanInstitute Theore 32001, of R.O.C. Physics, Academia Sinica, b c d a the lower mass regime. We compute the expected signal signifi Keywords: ArXiv ePrint: using detailed simulations of signalfor and irreducible two more backg scenarios usingalso the show 8-TeV the data discovery and reach taking for approp each scenario at the 14-TeV into a pair of bottom quarks, propose to use the photon associated production of the the current bound on the at the LHC collisions with an integrated luminosity of 19.6fb other methods need tostraints be and employed dijet for data this atat the lower 95% LHC, mass confidence we regime. level. find No that bound only can one be of obtained the from e about 1TeV. However, this constraint does not apply to the ca scenarios of the Open Access Article funded by SCOAP Abstract: Cheng-Wei Chiang, Phenomenology of JHEP05(2014)106 – 5 7 8 9 1 3 5 10 10 13 14 16 bosons els [ symme- ′ 2 Z Z symmetries in ious motivations in Collider (LHC) has pro- ] with a mass of about r various models beyond V runs, while taking into 2 utral gauge boson usually etry in models. Therefore, oweak phase transition, as , ar impose lower bounds on 1 k symmetry breaking; namely, urally emerge from a local U(1) ]. Properties of such st to discuss what kind of signals ]. Besides, the discrete 21 7 – 3 phenomenology in various models, please ′ model [ Z 6 ′ – 1 – E Z ′ Z m bosons are essential to distinguish such new physics mod- ′ mass by current data Z ′ Z ]). boson 23 process ′ , ¯ t GUT model t plus dijet events Z 22 ]. An extra U(1) has also been employed in supersymmetric mod 6 → 15 E – boson. For example, there are usually additional U(1) gauge 8 pp W/Z ′ Z An extra U(1) gauge symmetry is often introduced based on var 3.5 Summary of constraints on 3.1 The 3.2 The dijet3.3 process The 3.4 The constraints from UA2 ] (so-called UMSSM) to facilitate a strong first order electr try required for stabilizing darkgauge matter group candidates [ can nat see, for example, [ required to realize successful electroweak baryogenesis [ the SM. Moreover, nulltheir results masses of and/or new any physics other scales.from new new It is particles physics of can so great be f intere account expected the at data the collected upcoming in 13-and the 14-Te 8-TeV run. 126GeV. This fact becomes a strong guidance for us to conside els (for nice and comprehensive reviews on strongly depend on thephenomenological origin studies of of the corresponding U(1) symm 20 The operation of the 7- andvided 8-TeV runs us of with the quite CERN important Largethe information discovery about electrowea of a standard model (SM)-like Higgs boson [ A Review of 1 introduction 4 Photon associated production of 5 Conclusions 3 Constraints on the Contents 1 introduction 2 Leptophobic grand unified theories (GUT’s) such as the physics beyond the SM,called resulting the in an additional massive ne JHEP05(2014)106 6 ], ]. Y E can 40 31 , for – – ′ raints boson ns are at the bγ Z ¯ 28 29 b Z process to → process due γ ¯ q ′ bγ osity required ¯ b q Z boson in the ′ → → → Z contribution to the − mass only in one of γ e ′ ′ boson with the mass ′ pp w the interaction La- + ′ charge of each fermion Z Z Z , events observed by the ] and the LHC [ e ′ ′ Z nd at the UA2, deriving ost scenarios, the Z Z 31 8TeV with an integrated → ]) events. ting such a particle at the phobic – e free parameters. They can W jj 25 bosons derived from different 28 pp ound events. With a detailed [ boson does not couple to the sult of signal significance as a ′ efore, we propose a promising to the ′ ′ − Z data at the LHC. However, this Z τ Z processes have been measured at ¯ t + t mass from various experiments are τ ′ boson had been done in refs. [ → ]( ]. Zjj Z ′ ′ , where the decay and production of the 24 40 ]. First, we consider the bound on the Z Z ], a leptophobic [ 2 – , at the LHC to search for the leptophobic 41 ′ and 36 − 37 → – µ Z + boson that couples to a dark matter candidate 34 pp µ ′ – 2 – W jj Z . t and mass is below the threshold for decaying into a pair m − ′ , we propose to use the e 4 Z + ]. In refs. [ e boson in section boson with fermions are the same as those of the searched for at the Tevatron [ ′ ′ 33 ′ case), the lower mass limit has been found to be 2.86TeV Z ], there is a kinetic mixing between the hypercharge U(1) Z , Z ′ (1) TeV by the 27 32 Z O charges for the left-handed and right-handed charged lepto , ′ by using 26 Z 1 . In section boson. A detailed simulation is presented to show what const bosons have been performed mainly using the dilepton events 3 − ′ GUT. ′ Z 6 mass. In addition, we further estimate the integrated lumin Z ′ E model [ Z 6 mixing had been analyzed in ref. [ E ′ Z - Z We further focus on the pair decay mode of The structure of this paper is organized as follows. We revie In the In this paper, we discuss all possible scenarios with a lepto However, such searches become ineffective when the Searches for Phenomenological studies of the leptophobic are also discussed. The current bounds on the mass according to current data of collider experiments. In m boson with a mass smaller than 2 ′ ′ ′ Z the advantage of using doublesimulation b-tagging of to signal reduce and the background backgr function events, of we the obtain the re cross sections compared to thechannel, experimental the error photon bar. associated production Ther of grangian for the leptophobic the LHC, no bound can be obtained currently because of a small for a 5-sigma discovery for the 14-TeV LHC. of top quarks. Werespectively also a take into lower account bound dijet of data about at 500GeV the LHC and a 250GeV on the the scenarios. In addition, although the method does not apply when the be excluded up to about search for a light to the (1.90TeV) at the 95%luminosity of confidence 19.5fb level (CL) from collisions at we could have using the current data and the prospect of detec Tevatron CDF Collaboration. Effects of the leptophobic . In this paper, we focus on the study of leptophobic reviewed in section LHC. If the couplings of the Z Z with collider signals forLHC the collider signatures of a leptophobic group and the extra U(1)’s after GUT breaking. As a result, th (the so-called sequential scenarios of the of about 150GeV was proposed to explain the excess in the had been studied in refs. [ GUT model, differing in particle embeddings [ zero, rendering the leptophobia nature. is a linear combinationbe of chosen so these that U(1) the charges, involving two JHEP05(2014)106 , ′ . g ′ 2 q 3 2 Z / (2.1) (2.3) (2.2) m m 5 plane, can be ′ p Q = decaying is always ¯ Z ′ q Q otal width u = / x Z ¯ of the quark d ′ Q implicity, we ¯ . Z f Q g ¯ the ) Q with and u, d | , s. In our paper, the Q = q ¯ x charge q Q n the details of matter 4 ′ / u Z − ions are the same in these ¯ Q (for 1 | us leptophobic scenarios are n cross section for , I as they are affected by the p The vector coupling coefficient , ′ µ q # 2 . A brief review of the different x  qZ 5 charges, and Scenario-II have the 4 )  q Q q ′ q ¯ Q ¯ − GUT model that realize leptophobia Q a Q ¯ Z ), on the ¯ 5 Q charges. We note here that the value 1 Q 6 . Among the eight scenarios given in ¯ q γ − ′ q Q E p − 1 ¯ Z − Q )] 1 → q  / q ], we adopt for definiteness v d ′ are related to the  x ( Q ¯ 4 q q Z Q 2 µ 42 ¯ ( x Q a – 3 – − B ¯ qγ ′ − = (1 and Z mass, the terms inside the square brackets involve 2 boson with SM quarks are given by q 2 q g ′ d,s,b  ′ a Q as the horizontal axis is simply because = Z q Z Q ¯ u,d at the TeV scale can be predicted according to renor- q Q ¯ Q ¯ Q , a = / Q ′ X ) + q ¯ P u Q q Z  model is given in the appendix.  ¯ / g x Q boson is assumed to decay into only SM quarks. The reason = u q 6 Q ′ ¯ ¯ ¯ Q L Q E Q Z 1 + listed in table IV in the appendix are assumed to be so heavy phenomenology can be safely neglected. " ′ h into a quark pair is (1 + 2 2 Q 2 q Z ′ 1 + boson 2 ¯ v Q [ Z  ′ ′ ′ Z Z Q π π Z 2 4 4 ¯ Q m m ′ ′ charge ratios, 2 2 Z Z = represent the up- and down-type quarks, respectively. For s that depends on the g g ′ q , we show the contour plot of the total branching fraction for d q Z v 1 = x = 1TeV as an example. Here we note that in the calculations of t factor. ) = boson, along with the corresponding ′ ¯ q is the hypercharge coupling, for phenomenological analyse ′ Z Q q and ′ ¯ Z Q m , Scenario-I and Scenario-IV have the same g u → 4 ′ The decay rate of In figure Z and the axial-vector coupling coefficient by q Γ( q assume no or at leastv negligible flavor-changing couplings. where malization group running fromcontents and the unification GUT scale. scale, which As depends in o ref. [ of the gauge coupling constant The interactions of the leptophobic for the where we use the absolute value of 2 Leptophobic table non-SM fermions such as just the two that their effects on the and branching fractions, the negative among the scenarios. The predictions for the vario taking The appendix briefly reviews the scenarios in the leptophobic scenarios in the Apart from into a pair of down-type quarks, same charge ratios asthree them, scenarios. so However, that the the total decay width branching and fract the productio different between Scenario-I oroverall Scenario-IV and Scenario-I 14-TeV LHC. Our findings are summarized in section JHEP05(2014)106 ′ Z and mass ¯ s s ′ Z → ′ Z . The column 4 , ¯ ). The general d d 2.7, 5.4, 8.2 1.7, 3.9, 5.9 2.3 width [GeV] 3.2, 7.2, 11.1 3.2, 7.2, 11.1 0.73, 1.6, 2.4 3.6, 7.7, 11.7 0.32, 0.72, 1.1 5.7, 12.8, 19.6 → ′ Z scenarios that present ( imum (less than 5%) are ¯ c = 500 GeV, 1000 GeV and c (VI) 10 decaying into the down-type ′

Z comes smaller for larger ′

[%] → 5% Z m ′ ¯ d

Z d 10% 7.9, 7.0, 6.8 0.6, 0.6, 0.5 = 1TeV. Predictions for the scenarios We note that varying the 11.0, 9.9, 9.7

and ′ 29.3, 28.7, 28.5 18.4, 17.1, 16.9 21.4, 20.2, 19.9 (V) 20% dependence in eq. ( Z (I, II, IV) (V’) ¯ u

|

q m u 30% Q x

in the scenarios listed in table → /Q 40% ′ u ′ 1 , i.e., Scenario-I, Scenario-III, Scenario-III’, ′ Z Z |Q [%] Z (III) – 4 – ¯ t (III’) t

2.2, 4.2, 4.6 50% 7.9, 14.4, 15.7 6.3, 11.7, 12.8 11.8, 20.8, 22.5 13.5, 23.5, 25.3 22.3, 30.4, 31.7 plane in the case of 90% 70% 95% 60% 80% Q ¯ Q , where the branching fraction of each mode and the total = 500, 1000 and 1500 GeV. / 1 ′ d 0.1 [%] 1

Z ¯

Q 10

0.1

Q d ¯

u m /Q Q u and 5.0, 4.9, 4.9 | 31.5, 27.8, 27.2 14.8, 13.9, 13.7 37.9, 34.0, 33.3 27.6, 24.7, 24.2 18.4, 17.1, 16.9 Q ¯ Q in the appendix are indicated by the red crosses. / u 4 ¯ Q | ) displays the branching fractions for . Contour plot of the total branching fraction for the ¯ d ). The three numbers in each entry are predicted for . Branching fractions and total width of d b ¯ ( b ¯ u Scenario-VI Scenario-IV Scenario-III Scenario-III’ Scenario-V Scenario-V’ Scenario Scenario-I Scenario-II In the following discussions, we will concentrate on the six u → ′ Scenario-V, Scenario-V’, and Scenario-VI. mass, as reflected in table distinct branching fraction patterns of the indicated by red crosses. Therealized maximum in (about Scenario-III’ 85%) and and the Scenario-VI, min respectively. 1500 GeV, respectively. Z width are computed for tendency is that the total down-quark branching fraction be for Table 1 defined in table Figure 1 quarks on the will cause shifts in the contours as a result of the JHEP05(2014)106 ′ ¯ t 1 t Z − and → Z ′ ast two Z pp process to → 1000 γ by the black, contributions ′ ′ for the collision pp Z Root(s) = 14 TeV Root(s) = 14 Z ′ − , Z γ m -channel ′ W → m s ) cut. Z γ region, the produced t panel). The biggest [GeV] ( ′ pp → Z’ and T Z p m onances decaying into ) denotes the transverse + e generally ranked in the m pp cenario-VI (Scenario-III), for the parton distribution γ n upper limit on the cross ( W T e production cross section of grated luminosity of 19.6fb p ergy of 8TeV (dashed curves) mass in the six scenarios. We ses and those in the subsequent plus dijet processes at the LHC, ′ CTEQ6L ) process of associated production. Z ± Scenario V Scenario III Scenario III’ Scenario V’ Scenario I Scenario VI W/Z W 1 3 4 2 0 at the LHC are the 100 -1

10 10 10 10 10 process, the ′ 10 process as a function of σ (pp Z’) [pb] Z’) (pp ′ Z ↑ and 10GeV cut for the , as a result of the Z W ′ W > ′ Z → γ, Z – 5 – Z , dijet and ) ¯ t γ pp t → = ( T and V → p pp ( ] package and using ′ -channel production cross section is shown as a function Z charge for the up-type quarks. ′ Z 43 s V [ ′ 1000 u Z mass by current data Z ¯ → Q ′ Root(s) = 8 TeV , the → pp except for Scenario-VI. In the large Z 2 pp Z ′ CalcHEP [GeV] Z Z’ process m couplings extracted from UA2 experiment. ¯ t and t -channel ¯ qq t ′ W ]. They analyzed the events with one or electron and at le ′ → , the associated production cross sections for the Z Z 3 44 , pp processes for each of the scenarios are shown as a function of γ ′ . Production cross sections of the Scenario VI Scenario V’ Scenario I Scenario III’ Z Scenario V Scenario III W ′ for the collision energy of 8TeV (left panel) and 14TeV (righ ′ 1 3 Z 4 2 0 100 -1 -2

Z 10 reduces faster than those of 10 10 10 10 In figure Dominant production mechanisms for the

10 10 σ (pp Z’) [pb] Z’) (pp → m γ ↑ ′ as well as the The CMS group reported the search for production of heavy res 3.1 The consider the current data on pairs in ref. [ at 8TeV. Since no excess in events is observed, they provide a 3 Constraints on the momentum for the photon.order of In most cases, the cross sections ar vector boson tends toZ get smaller transverse mass, so that th In this section, we discuss various constraints on the avoid collinear singularity of the produced photon, where are summed over. We impose the We calculate the production crossanalyses sections with for the help these of proces jets in the final state using the data corresponding to an inte (smallest) cross section inbecause of the the whole larger mass (smaller) range is given by S of functions (PDF’s). In figure red and blue curves,and respectively, 14TeV also (solid for curves). the collision For the en Figure 2 process and the energy of 8TeV (left) and 14TeV (right) in the six scenarios. pp JHEP05(2014)106 ′ Z for pair ′ Z ¯ t t m process, γ ′ Z 1000 1000 1000 2% with Γ . Scenario V → Scenario III Scenario VI pp = 1 ′ Z [GeV] [GeV] [GeV] /m Z’ Z’ Z’ ′ in our scenarios, we can process as a function of m m m Z ¯ t ¯ t t t ted by the dashed curve. In → -V, -V’ and -VI (right panel). → i.e., Γ ′ ) process as a function of ′ Z ± Z γ d curves). For the γ γ W Z’ → Z’W Z’Z Z’Z Z’ Z’W → Z’ Z’W Z’Z . ′ pp Z and 1 1 1 2 0 2 0 2 0 100 100 100 -1 -1 -1 -3 -3 -3 pp -2 -2 -2 -4 -4 -4

m

10 10 10

10 10 10 10 10 10 10 10 10 10 10 10 10 10 10 10 10 10 σ σ σ (pp Z’V) [GeV] Z’V) (pp (pp Z’V) [pb] Z’V) (pp [pb] Z’V) (pp ↑ ↑ ↑ as γ, Z ¯ t t = – 6 – M V ( V ′ Z → 1000 1000 1000 Scenario I Scenario V’ Scenario III’ pp by identifying ′ Z resonances at 95% CL as a function of invariant mass of [GeV] [GeV] [GeV] m ¯ t Z’ Z’ Z’ t m m m 10GeV to avoid the collinear singularity. > , we show the cross section of the ) 4 γ ( γ T γ p Z’ Z’Z γ Z’W Z’Z Z’ Z’W . Cross sections of the Z’W Z’Z Z’ 1 1 1 2 2 2 0 0 0 100 100 100 -1 -1 -1 -3 -3 -3 -2 -2 -2 -4 -4 -4

in Scenarios-I, -III and -III’ (left panel) and in Scenarios

10 10 10

10 10 10 10 10 10

In figure 10 10 10 10 10 10 10 10 10 10 10 10 σ σ σ (pp Z’V) [pb] Z’V) (pp (pp Z’V) [pb] Z’V) (pp (pp Z’V) [pb] Z’V) (pp . Comparing this limit with the cross section of ′ ¯ t t ↑ ↑ ↑ Z M obtain a constraint on we impose section of producing m Figure 3 the collision energy of 8TeV (dashed curves) and 14TeV (soli The experimental upper limitthis for calculation, the the narrow cross width section assumption is is employed; indica JHEP05(2014)106 V, ] put al line 45 mass and 2500 for the collision energy [GeV] ]. ′ Z’ 2000 Z 44 m m ta [ Scenario VI n and property analysis of a rom this process in Scenario-III D events at the LHC, ref. [ exp L Χ ' -I, -III and -III’ (-V, -V’ and -VI). The F Scenario V Scenario V’ 1500 V D 600 800 1000 1200 1400 1600 1800 2000 H GeV @ ]. In Scenarios-I, -V, -V’ and -IV, the 1 0 ' -1 -2

10 10 Z 10 10 44 σ (pp Z’ tt) [pb] tt) Z’ (pp ↑ ↑ m Scenario – 7 – process as a function of ¯ t 1000 t Scenario I → at 95% CL. ′ χ Z F → , as used in ref. [ ′ pp Z 500 Scenario VI , defined in the text, in the different scenarios. The horizont Scenario V χ [GeV] F Z’ are extracted to be about 1000 GeV, 850 GeV, 800 GeV and 1900 Ge m ′ Z m boson as one can readily measure a peak in the dijet invariant ′

0.0020 0.0015 0.0010 0.0005

Z

Scenario I

Χ F D . Values of ∆ . Cross section of the Scenario III Scenario III’ 600 800 1000 1200 1400 1600 1800 2000 1 0 -1 -3 -2

10 10 10 10 10 σ (pp Z’ tt) [pb] tt) Z’ (pp ↑ ↑ denoting the total width of corresponds to the upper limit for ∆ lower bounds on dashed curve is the observed limit at the 95 % CL from the LHC da of 8TeV. The left (right) panel shows the results in Scenario Figure 5 Figure 4 3.2 The dijet process Dijet events at hadronleptophobic colliders are useful for the detectio respectively. On the other hand,and no Scenario-III’. constraint is obtained f study their angular distribution. Using the dijet resonant JHEP05(2014)106 , , ) ], . V ± < 47 exp 46 with 53 (3.2) (3.1) N . ′ boson ons of 6 TeV. . Z ′ p 2 07(syst / Z . 0 ≤ 96 as 2 TeV Such a new certainty in . is extracted ± 1 jj ) χ . cut jj m < F m χ ≤ ]. F boson. In ref. [ 48 us distributions [ ′ denotes an invariant 01(stat . Z 0 , cut jj | ame as the experimental ± m VI. On the other hand, no 02) 37 vents with a high invariant mass provided the coupling . . hobic nough compared to the dijet 0 fferent dimension-6 operators ) in the six scenarios of the ′ from the SM prediction with nterest to us is that the dijet , for the six scenarios. The 95% Z ss cut, 2 TeV tions mediated by a ± ) ) t of the QCD prediction. Thus, ) processes are given as 0 cut jj ′ χ mediation with the experimental Z µ F by requiring ∆ m (1 cut jj cut jj ′ 02) and pick the minimum on the ( ] and 0 . m χ Z χ or 0 SM F χ , m , m 49 F e 0 F ± . 32 . is − 30 3 ℓ ) pb [ . ( 02) . b ¯ χ < χ < b 0 ( ( − – 8 – ± N N ℓ + 05 (lum (1 ℓ as a function of ≡ . , instead of working with the effective Lagrangian. ′ data at 7 TeV. The central value of ] provides the dijet event data with 0 ) χ Z χ 1 → F ± 48 F being the rapidities, and cut jj − | ) b ¯ . 2 , m 1 ( Zb CTEQ6L y χ MIN F ] as the ratio of two numbers of events in different regions → 06 (th ≡ . 47 0 can be found in all the other scenarios. The peak at around 2Te χ ] and pp F χ ± ) with is indicated by the horizontal line. As shown in this figure, a | ) 51 F . ∆ 2 [ are respectively the values of χ y and F value [ − events had been measured at the LHC. The measured cross secti b ¯ SM χ plus dijet events χ 1 b ¯ F F y | and in the SM. In numerical calculations, there is about 2% un µνb 09 (syst , we show values of ∆ Zb . ′ 5 0 mass is taken to be much larger than the typical jet momentum. Z (= 28462) is the number of events measured at the LHC [ MADGRAPH → and ′ W/Z exp( ± ) ′ and Z b ¯ . 6 TeV based on the 4.8fb ≡ Z exp χ . b ¯ 2 F χ N W b as W b < The dijet measurement had been done at the LHC, offering vario We directly calculate the deviation in the value of In figure → χ ]. In order to compare the dijet events including the jj 05 (stat . for Scenario-VI is due to our choice of the dijet invariant ma mass smaller than aboutsignificant 500GeV deviation in is excluded only in Scenario- the help of interaction term can modify theusing dijet the distribution experimental from tha dijet events, one can constrain the pp 3.3 The The CL upper limit for ∆ constant is fixed. when the 0 the cross section. We therefore insert the factor (1 where where This is because the massinvariant mass. region considered The here deviation is can not be large expressed e as of it had been shownmass that could be the used angular to distribution probeby the of through mass the scales effective associated dijet Lagrangian withprocess e di approach. can Particularly receive of contributions i from four-quark interac to be about 0.0848. data, we define where m leptophobic 48 constraints on the mass and coupling constant for the leptop right-hand side. When thecentral SM value, one prediction can is set assumed a to 95% be CL the upper limit s on ∆ mass cut for the dijet system. Ref. [ JHEP05(2014)106 ; b ¯ ′ b Z − ℓ 1 for . 4 and + . 2 ]. We events. ℓ 2 51 < [ < | → 002 pb for | η . | b ¯ η | ove-mentioned 1 for b-tagged Zb . . Consequently, 2 3 W jj/Zjj 300 → e < MADGRAPH | pp and 20 GeV, ]. In all our scenarios, η | b ¯ rom the leptophobic 52 > 25 GeV and ], the cross section of the 01 pb and 0 using the current data of . and T ′ > 49 p Z b b/Zb ¯ ¯ T L m p L the other scenarios and heavier W b µνb 250 at 7 TeV [ UA2 in Scenario-VI (black horizontal line). event: H → UA2 1 25 GeV and R H b ¯ R b u ¯ − , D R g L , > Zb = 100GeV using L u process serves more useful as it gives a W b d T ′ g γ p ′ g Z GeV L @ → Z ' m , in search of any extra heavy vector bosons Z 1 pb is expected in order to explain the CDF 1 . . According to ref. [ → pp m 1 − – 9 – 2 jets had been measured in the UA2 experiment 200 − pp events with the invariant mass of the dijet system → 0 fb ¯ p ] compared with . 4 for b-tagged jets. On the other hand, the following p . Scenario VI 34 H 2 W jj couplings (blue curve for the down-type quarks and red curve R < u | ¯ qq g ′ η | Z 150 . A cross section of 8 W jj

0.70 0.50 0.30 0.20 0.15 0.10 2.00 1.50 1.00

25 GeV and R , L q g → > processes, respectively, which are much smaller than the ab ′ 106GeV for charged leptons, and b ¯ T p < WZ Zb production cross section is smaller than 1 pb as shown in figur . Constraints on the ℓℓ ′ → ]. boson in our scenarios is not constrained by current ], respectively, with 7TeV and 5 ′ and event has been obtained by taking the kinematical cuts 50 to be about 150GeV. This process can receive contributions f pp The CMS group also analyzed We calculate the cross sections of the WZ Z 50 b b ¯ ¯ < M masses. Thus, we cannot obtain any useful constraint on jj ′ anomaly, but is excluded using the data sample of 5fb at CERN with the data sample of 10.9 pb experimental errors. Similar resultsZ can be obtained in all W b larger cross section. 3.4 The constraints fromThe dijet UA2 invariant mass spectrum of i.e., these processes. M for the up-type quarks) taken from ref. [ the the jets [ find that the deviation in these cross sections are less than 0 W b As we will show in the next section, the 76 Figure 6 pb [ cuts are imposed to obtain the cross section of the muon, and processes in the SM and in Scenario-I with JHEP05(2014)106 . t m ], in case 2 (3.3) (3.4) ′ 34 < Z process ′ 300 GeV. Z jj < ng constant m ′ → Z to search for a ′ Z ifficult to extract bγ ¯ < m b io-V’ Scenario-VI → raints from the dijet in the appendix. In ¯ p at the center-of-mass → p 4 t is valid only when the γ e ′ case; namely, in the excluded region of Z the other scenarios are well ′ . The constraint from the events because of the small 2 ) are related to the variables Z esent a simulation study here. → u, d, ted by them mainly because of 3.3 decay is kinematically forbidden. pp W jj ¯ t = t , q ) and table ) extracted from figure 1 of ref. [ and q → a ′ 2.2 R,L Z ± d with Zjj q g ′ , v . , ( b ¯ t Z ′ discussed in this section. The lower bounds ′ µ Z m ′ and 2 g W b qZ Z – 10 – ′ 5 , > Z = m -channel process b R,L γ ¯ ′ t u 2 m Z g ∓ Zb L,R m q 1 g µ are given by eq. ( ¯ qγ at 95% CL for all the scenarios by existing experiments. The production. In the next section, we study the light q ′ process. ′ 350GeV, where the a L,R Z q γ ′ . ]. The fact that no excess had been observed can be converted g m couplings with quarks in the mass range 130 ′ WZ Z ′ 53 Z and Z → m q mass from the and v in Scenario-VI indicated by the horizontal line. The coupli ′ ′ pp are only valid for R Z ¯ t u with t g ZZ ′ → Z charges for up-type quarks. We also find that it is currently d 1000 GeV — — 800 GeV 850 GeV 1900 GeV pp Scenario-I Scenario-III Scenario-III’ Scenario-V Scenar ′ -channel ) by t ], constraints on the chiral couplings in Z at 95% CL for all the scenarios are listed in table decay is kinematically allowed. On the other hand, the const process is the strongest among all. However, this constrain . Lower bounds on ¯ t 34 , we show the upper limits for 2.1 250GeV in Scenario-VI. t ¯ ′ t ¯ t 6 t t Z . → in Scenario-VI and that including all the other couplings in m ′ → → L Z pp dijetUA2 — — — — — — — — — — 500 GeV 250 GeV ′ u Since no experimental data exist at the time of writing, we pr relatively light In this section, we propose to use the 4 Photon associated production of cross sections of constraints on the using the Except for Scenario-VI, allthe other small scenarios are not restric events and the UA2 constraint can be applied to the lighter Z g with that ofenergy the of upper 630GeV. limit The obtained chiral couplings from expressed the in eq. UA2 ( experiment pp figure comparison with in eq. ( into a constraint on the where the values of had been given in figure 1 by comparing the cross section for th that decay into two jets [ In ref. [ Table 2 bounds from below these constraintsm and thus omitted. We therefore obta 3.5 Summary of constraints on on Here we summarize the constraints on JHEP05(2014)106 , ¯ q 3 q ng (4.1) (4.3) → ′ , we use ′ Z = 8 TeV Z m s ackgrounds, , we take an PYTHIA-PGS om the b-jets. : √ process with b = ¯ S ] b ly. In table. b ¯ b , 56 M ¯ qγ q M S , Scenario-I, assuming → 4 . 360 GeV. Moreover, we 2 10 GeV pp nificance by more than a < > . ] through the rio-I in units of pb, assuming two b-jets | ′ ) Z γ jj 54 [ ( al and irreducible background , η ] m ]. For the generated events, we T s ∆ | 55 b γjj . ¯ and the [ − diation and hadronization effects. ) γb +10GeV (4.2) ) are imposed, and the double b-tagging bγ ¯ ′ PYTHIA b PGS s/b Z 4.1 ) b ¯ → b < m → b ¯ pp b ( background is significantly reduced by about ′ ) ln(1 + PDF’s for the collision energies b is the rapidity difference of the two jets. The – 11 – , | γZ + γjj < M jj ). The asymmetric distribution is due to the fact that signal s η detector simulation to reduce the background events. 2) ) 0.256 21.8 2952 0.66 4.2 . ∆ 2[( | 0 CTEQ6L ) 0.015 0.449 0.541 2.14 p PGS 4.1 , p − 360 GeV = 4.2 . The basic cuts eq. ( < (1 ′ 1 S decay is expected to have higher sensitivity than the , invariant mass distribution is asymmetric around Z − at the detector level, mainly as a result of soft radiation fr jj 4 b ¯ b . ¯ m b b bb 2 40 GeV = 8 TeV. The ] and the M = 8TeV as an example. To calculate the significance < M < > → s | ′ s 51 [ √ We then calculate the signal significance defined by [ quarks. Z √ cut in eq. ( 1 b b ¯ detector simulations. b (jets) (jets) refers to quarks in the first and second generations. For the b T η M Basic cuts in eq. ( Double b-tagging 0.0269 2.39 3.60 1.54 90 GeV | p are the numbers of signal and background events, respective q PGS value. b ′ Z m and . Cross sections of signal and background processes in Scena s = 200 GeV and cut restricts ourselves to the mass regime 100GeV = 200 GeV and In our analysis, we generate signal and background events usi Because the shape of the ′ ′ 1 jj Z Z Afterwards, we further take a cut on the invariant mass of the for each impose double b-tagging after the where the jets include b-jets, and M different upper and lower cut limits in eq. ( where three orders of magnitude byare double b-tagging down while by the one sign order of magnitude, thereby enhancing the sig and 14 TeV. The generated events are passed onto MADGRAPH/MADEVENT events tend to shift to lower we show as anm example how the cuts affect the number of events in package to include initial-stateThe radiation, detector level final-state simulation ra isfirst then apply carried the out following by basic kinematical cuts: is applied after With b-tagging, the integrated luminosity of 19.6 fb Table 3 m mis-tagging of the decays, where we include the SM irreducible background JHEP05(2014)106 , ′ bγ ¯ sic Z b γjj and 350 350 m s and cut 1 → b b 5 γ M ′ = find that + Z 14 TeV S 300 300 cut → ction of cut, the mass b b tagging b M = 8 TeV and an pp b ¯ b shows the result + ' D s D V 8 M √ 250 double 250 + GeV e required integrated @ tagging GeV ' @ b Z ' , given in table. Scenario III' Scenario Z cut. b ¯ m m b b ¯ Scenario V Scenario V b Scenario III' double nalysis. The hierarchy in Basic cuts 200 . The left panel shows the 200 M + → 1 ' = 5) from the osing the ′ oduct of the cross section of − V nd the right panel that after t panel shows the result after Scenario I S Z Scenario III cut. Scenario I Scenario VI b ¯ Basic cuts 150 b Scenario III Scenario ing the Scenario VI 150 M 50 500 100

5000 1000

4.0 3.5 3.0 2.5 2.0 1.5 1.0 0.5

fb Luminosity

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1 process at the LHC with - . The left panel in figure ′ cut is effective in reducing not only the Z bγ ¯ b ¯ b b m – 12 – M → 350 350 γ ′ 200GeV can be excluded at 95% CL for Scenario-V’ Z 5 tagging b = . 14 TeV S → ′ 300 300 Z double pp m + . The left panel shows the result after imposing the basic cut background. 1 , and the branching fraction of D . − 290 (240)GeV can be excluded for Scenario-V’ (Scenario-I) at = 14TeV. The left panel shows the result after imposing the ba D 3 bγ 250 ¯ s 250 . b 6fb ' GeV . Basic cuts cut. We thus find that a 5-sigma discovery can be obtained for √ ′ @ GeV ' @ Z ' Z b ¯ = 5 as a function of Z b m tagging m m b Scenario V S M 200 . Scenario III 200 ' Scenario V double cut. Assuming the data are consistent with SM prediction, we V ' Scenario III + , we show the signal significance for the six scenarios as a fun Scenario III b ¯ Scenario I 7 = 8TeV and an integrated luminosity of 19.6fb b Scenario V' Scenario VI s Scenario I M 150 Scenario √ 150 , shown in figure Basic cuts Scenario III . Significance for the . Required integrated luminosity for 5-sigma discovery ( γ ′ . Scenario VI 1 50 Z 100 500

5000 1000

In figure To study the discovery reach for the 14-TeV LHC, we compute th

0.5 3.0 2.5 2.0 1.5 1.0 4.0 3.5

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Significance → 1 - 95% CL. The otherthe scenarios significances will of be thepp less different constrained scenarios depends by this on the a pr range of 120 GeV luminosity to reach using the basic cuts and double b-tagging. After further imp background but also the the mass range of 130 GeV result after imposing thetaking basic the cuts and double b-tagging, a integrated luminosity of 19 figure after imposing the basic cutsfurther and taking double the b-tagging. The righ factor of two. We also observe that the process at the LHCcuts with and double b-tagging, and the right panel that after tak assuming Figure 8 Figure 7 double b-tagging, and the right panel that after taking the JHEP05(2014)106 ′ ′ ′ ge Z Z ZZ in as- l data, VI, re- . There ′ mass, in- ′ ¯ qZ Z q fundamental boson at the 1fb. If such a ′ 6 . → Z E by applying only mass comes from ∗ ′ 1 , differing in the ′ /Z − Z ∗ ned process to study b Z . On the other hand, hobic train the γ t can use the this process and the extra U(1) sym- m ] in a model-independent way → enarios have the same 2 hat it is difficult to obtain lds in the boson, it can still be pro- e the simulation study for om which the lower limits searches at the ILC will be Y 57 uch a boson is not found at tinct scenarios to six. − ′ ′ < e o the signal of four hard jets at 95% CL are about 1 TeV, GeV, 350 GeV and 500 GeV. Z Z ′ + ′ cut, the reach can be extended e Z Z boson that can be derived from b ¯ these scenarios can be related to b eptophobic m ′ m Z M mass. For example, the cross section of ′ 190GeV in Scenario-I. With an integrated Z . ′ – 13 – Z process, it suffers from a kinematical disadvantage. ′ m plus dijet events and the UA2 data. When the top ¯ tZ In particular, it would be interesting to analyze the t Even though the ILC is an electron-positron collider 3 → plus dijet events due to the small cross sections of 2 W/Z − ]. e + at the ILC has been discussed in ref. [ 58 e ′ W/Z Z processes. − 9TeV in Scenario-I, Scenario-V’, Scenario-V and Scenario- = 150GeV at a 250-GeV ILC is estimated to be 0 τ . and all cuts mentioned above, we can cover the entire mass ran ′ + because it is difficult to probe using the current experimenta Z 1 /τ t − m − m boson with a mass smaller than these energies can be produced µ mass from 2 ′ + is kinematically allowed, the strongest bound on the ′ µ , the dijet events, ′ Z Z < ¯ t with t Z ′ → ′ process. In this case, the lower bounds on Z − ¯ t → 85 TeV and 1 e 290GeV in Scenario-V’ and t ¯ m . production. qZ + q ′ e pp . GUT model, as a result of kinetic mixing between U(1) → 200GeV in Scenario-V’ with an integrated luminosity of 100f boson at the ILC. A detailed analysis for leptophobic ′ → 6 ′ Z . WZ We have taken into account current experimental data to cons Finally, we would like to comment on the search for the leptop pp E Z − Recently, phenomenology of Although one can consider the ′ is discovered in the 14-TeV LHC, one may use the above-mentio m 2 3 e Z 8 TeV, 0 ′ . + spectively. However, this channel is not effective when only Scenario-VI is constrainedare by given as the 500GeV dijet andconstraints and 250GeV, on UA2 respectively. data, We also fr found t and 0 charge ratios. Therefore, theone production another cross by sections simple of scaling. This reduces the number of dis the charges for the quarks and the exotic fermion. Three of the sc international linear collider (ILC). cluding pair decay of representation, there are eight possible scenarios with a l in the plots for Scenarios-V’, -I, and -III’. metries. Due to different embedding schemes for the matter fie sociation with the light quark pair. the luminosity of 500fb to the basic cuts and double b-tagging. With further the are several designs ofTherefore, the the ILC collision energy, namely, 250 using the 5 Conclusions We have studied the phenomenology of a leptophobic case with where the initial leptons do not couple to the leptophobic e as we have discussed inwith the the previous invariant section. mass This of will two lead sitting t at the Z m duced in association with the quark pair production, i.e., presented in a separate work [ detailed properties of the newthe boson. LHC and Even the in exclusion theas limit case a has where not discovery s reached channel. thethe 95% In CL, any one case, it is important to prepar JHEP05(2014)106 Y ne- (A.2) (A.1) (A.3) (A.4) ]. The 42 , with the χ . ′ boson followed Q , ′ is the SM U(1) data at 8 TeV. A ! Z discussions during U(1) 1 Y µν µν and U(1) ′ − he ˜ × ˜ B Z ψ or the gauge fields and 008-003-MY4, NSC-101- SM to explore the constraints 250GeV can be excluded G ! b ¯ charges running inside the ons given in ref. [ ble background events, and rted in part by the National . χ γb → 1 Y ′ al significance. We have found han Scenario-VI. Specifying the ψ , respectively. Z ψ , → , respectively. χ ) ′ ′ m g µ χ θ, ′ and 1 sin ˜ U(1) would be proportional to the factor Z γZ ′ ′ sin sin and × χ Q Q χ → ′ GUT model that predict a leptophobic

Y χ Z Q ) ) with 6 gauge couplings, and g and U(1) 6 pp ′ µν − E 190GeV in Scenario-I. E ψ Y ˜ + ˜ Z 3 for θ U(1) / , µ . 5 ˜ × ′ B µν – 14 – cos p Z ˜ Y B ψ ′ ( m g Q 1 4 and U(1) + SU(5) 5 and = − / a ′ µ L 3 are given by for the 14-TeV LHC, a 5-sigma discovery can be reached → Q W p aµν 1 ψ ψ a − quarks helps reducing background events significantly. We W gT b a ( µν U(1) µ follows the pattern of 300GeV has also been obtained for Scenario-V’. Assuming an W × 6 ¯ 1 4 ψγ . E GUT model − − ′ 6 Z = = are the charges under U(1) E m χ SO(10) int We note in passing that the kinetic mixing can be obtained at o are the SM SU(2) kin Q L ′ L → g into a pair of 4 symmetry is obtained as a linear combination of U(1) 6 ]. In this case, the kinetic mixing sin ′ ′ 290GeV in Scenario-V’ and and E 60 Q Z and ψ , . ′ g Q 59 Z The most general kinetic terms, including kinetic mixing, f We have proposed to use the photon associated production of t m We do not pull out the factors of boson, with its detailed derivations and fermion interacti 4 ′ interaction terms for a fermion where corresponding charge expressed as The U(1) loop level with the matter contents of non-zero symmetry breaking of hypercharge. Z by the decay into a pair of bottom quarks, i.e., at 95% CL aftersimilar imposing bound all of the cuts on the current LHC 19.6fb where in the lower mass regime,decay particularly of for scenarios other t loop [ that Scenario-I (usually called the standard have performed asearched detailed for simulation appropriate of kinematical signal cuts and to irreduci increase sign integrated luminosity of 100fb We present a brief review of scenarios in the for 2811-M-008-014 and NSC-102-2811-M-006-035. A Review of Acknowledgments C.-W. C would likethe very to early thank stage D.Science of Choudhury Council this of project. and R. N. This O. Gaur research C. was for under suppo useful Grant Nos. NSC-100-2628-M- JHEP05(2014)106 6 6 ¯ (A.5) (A.8) (A.7) (A.9) (A.6) 12) 12) 6 Q / / / / 6 / 6 1 1 5 / √ 1 11 − − 0 0 − 3 ) charges / 12 (1 ′ / f 6 12 12 ( 10 Q 5 2 2 2 2 ( 12 / / / 6 1 ¯ √ / / / / / 0 Q 1 1 1 − 0 ¯ √ 1 1 1 − 1 2 5 Q − p = 4) 4) χ − / / δ Q 1 = − 10 δ 4 4 (1 4 1 1 2 . Scenario-VI √ = 0, / / / 2 4 4 ( 2 − − 3 − 3 0 ′ 3, 1 1 1 . of mass eigenstates. θ / / / / Q 1 1 − 1 − − )) 5 χ . µ ψ tan L p Q χ ( B 6 ′ = 0 is = Q 2 1) √ tan θ ψ , Q δ 2 1 1 1 1 − 4 10 − ) f ′ 1 1 (3) ′ √ ′ Scenario-III (Scenario-III’) µ tan Z 2 0 − 3 − 3 ( 3 and g , g 12) 12) ) + ′ µ / / ¯ ψ c 5 3 QZ 5 nd scenarios with a leptophobic ! e ′ Q Z ) (= 2 − 6 ( ′ µ c Z µ ′ r 12 (1 √ e g / 2 4 1 1 1 1 (1) 1 (1) Z B GUT model. Fields with a superscript 6 3 12 ( Q ( 5 12 ′ / / / / ¯ (1) required to realize leptophobia. 1 0 Q 1 1 − 0 6 ) charges, all the other + is the GUT scale. Then it would be 5 6 6 ¯ Q ≡ − Q / / f O E 6 3 µ p 6 1 1 ( / / ) = − ! 4) 4) δ − 3 √ 0 1 1 − − 0 c / / ¯ / Q 1 = e χ ′ = GUT YB 10 ( − δ ′ χ 4 (1 4 Q √ ¯ / / 2 2 2 g 6 1 1 Q 4 4 ( 2 M 1) to ′ 1 1 / / / − 27, / / / . tan √ − 2 1 1 1 − / Q 1 0 1 − − 1 with for a fermion field = + 5 (0 , δ δ , − χ p ¯ a χ µ ) Q ) 2) 1) – 15 – Q O c Q c = 0 sec 1 − − 15, e W 10 e θ 10 √ ( 1 1 2 5 Scenario-II ( = 0 a 1 1 ( 2 ( 2 5 Scenario-V (Scenario-V’) √

δY , √ 2 − 3 − − 3 − ψ χ = 2 − 3 − − − − tan 3 5 δ θ = gT Q Q 2 1 ) charges are determined by two unknown parameters; ψ ψ ( charge r 2) Q f tan Q µ ! 6 ), where the sum is taken over the matter contents inside ( ′ 6 − − 2 2 2 (1) ) + ) + √ µ √ ¯ µ ) Z ′ ¯ Q 1 2 1 1 − 1 1 1 − 2 1 1 ( − 1 ψγ ) + L L ˜ ˜ L B Z ( ( f 2 ( − GUT ¯ ¯ ′ Q ( 6 6 χ Q ψ 6 6 ′ are diagonalized to the fields / / / /

6 3 6 3 15 5 5 15 5 5 Q = Q / / Q / / Q ), all − − 0 √ 5 5 0 /M µ √ 5 0 5 − − 0 2 2 3 3 2 ˜ / / | B int ′ 1 ′ ≡ 1 q ) = = Q − Q A.7 − 2 2 2 2 2 2 | L ) / / / / / / , and the L 15 15 1 1 1 = 1 1 1 = θ f ( χ ( δ − − − 1 √ 1 1 δ √ 1 1 − − − 1 ln( and ¯ ¯ Q 5, 5, Q ′ / / χ χ µ Y tan is the electroweak scale and ′ 3 cos 3 ˜ Q Q Z | p p / Q 10 Scenario-I 10 ′ Scenario-IV q 1 2 1 2 1 2 1 1 1 = = | √ √ Z 2 − − − 3 − − 3 − 3 − 2 − − θ θ ˜ P g . This implies that once we fix two of ) ψ ψ tan tan 2 δ ≡ Q Q 6 π ′ 6 2 2 2 √ √ Z . U(1) charges of six leptophobic scenarios in the 1 − − 1 2 1 1 1 2 1 1 1 − 1 g and (24 c c c c / c c c c θ d h L e Q u ′ e Q u d h L Z ; that is, ˜ g ′ denote the corresponding charge-conjugated fields. ′ These two equations are solved to render the gauge fields Through a non-unitary transformation, the loop, and The interaction terms are then rewritten as As is evident from eq. ( Table 4 i.e., g c possible to obtain the kinetic mixing of where are uniquely determined as well.Z We utilize this feature to fi JHEP05(2014)106 , , ] ]. , odel ommons models model ]. 6 SPIRE , is a non-SM E IN U(1) h , ]. ][ SPIRE . Thus, one can IN d Int. J. Mod. Phys. ][ tic fermion denoted f , arXiv:1101.5713 SPIRE (2012) 1 [ IN , [ GeV with the CMS . After the interchange, the B 716 redited. 125 superstring models h ]. ]. 6 ’ and Scenario-V’, respectively. arXiv:1205.6416 E [ ]. (1987) 878 ]. In this table, only (2011) 016004 SPIRE SPIRE arXiv:1207.7235 [ IN IN 41 SPIRE Phys. Lett. ][ ][ D 36 IN , , U(1) charges of the fermions are listed D 84 TeV-scale seesaw with loop-induced Dirac 4 ][ with those of superstring-inspired models Dark matter and Higgs boson in a model with d (2013) 073004 (2012) 30 gauge symmetry breaking Masses of dark matter and neutrino from TeV 6 ]. L E – 16 – − Phys. Rev. B ]. , Phys. Rev. D 87 ]. . In table flavor symmetry in supersymmetric extra , B 716 (1) 6 SPIRE 2 U E IN arXiv:1111.0599 arXiv:0910.3370 Z [ [ [ charges of New supersymmetric left-right gauge model: Higgs boson SPIRE hep-ph/0610006 SPIRE × [ χ ), which permits any use, distribution and reproduction in Discrete gauge symmetry in continuum theories IN Low-energy phenomenology of superstring inspired [ 4 IN ]. [ breaking S are different from the original ones only in Scenario-III and Neutrino masses and CDM in a non-supersymmetric model L Phys. Rev. h , − Phys. Lett. ]. Observation of a new particle in the search for the standard m , B SPIRE IN Observation of a new boson at a mass of and (1989) 1221 (1) and U(1) (2006) 336 ][ U d CC-BY 4.0 (2012) 033004 (2010) 033007 (1987) 274 ψ SPIRE (1989) 193 62 IN This article is distributed under the terms of the Creative C representation of 183 Phenomenological aspects of B 643 D 85 D 82 D 36 27 collaboration, ]. 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Shimomura, Q interchange the U(1) fermion whose SM gauge quantum numbers are the same as those o References any medium, provided the original author(s) and source are c by for the six scenarios, following the convention of ref. [ Scenario-V. We denote the two new scenarios by Scenario-III Open Access. Attribution License ( JHEP05(2014)106 , ]. ′ , data U(1) ′ ] ]. SPIRE ) boson Z , , ] ′ IN crisis y hadronic b, c Z collisions ][ ) ( -extended , ′ ′ c R ( SPIRE flavor pp model , R IN mixing 2 - [ C ) of U(1) U(1) ′ , Z b ( 1 Z , (2009) 1199 × - U(1) − R 4 Z , fb S (2013). 81 hep-ph/0001204 ATLAS-CONF-2013-066 [ , (1985) 36 -MSSM ′ arXiv:1106.4717 , ]. [ hep-ph/9604298 and the [ s ]. ]. ]. ]. ]. U(1) connection of LEP ]. B 155 ′ SPIRE ]. ]. ]. ]. ]. Z U(1) IN SPIRE SPIRE SPIRE SPIRE SPIRE ][ resonance at the LHC (2011) 855 SPIRE (2000) 013006 Rev. Mod. Phys. IN IN IN IN IN (1996) 226 ′ SPIRE IN , SPIRE SPIRE SPIRE SPIRE ][ ][ ][ ][ ][ Z IN ][ flavor symmetric extra IN IN IN IN 126 ][ On the anomalous electroweak baryon Radiative type-I seesaw model with dark 4 ][ ][ ][ Phys. Lett. D 62 ][ Baryonic S , B 381 ATLAS-CONF-2013-017 Leptophobic Implications of generalized , – 17 – Six- Like-sign dilepton signals from a leptophobic gauge bosons Two component dark matters in ′ TeV with the ATLAS detector arXiv:0909.2641 [ Phys. Rev. Z , Phys. Lett. Flavor changing effects in theories with a heavy arXiv:1008.3106 arXiv:1308.3389 arXiv:1303.7056 hep-ph/0703041 arXiv:0704.0328 arXiv:1207.7061 = 8 [ [ [ [ [ [ , s hep-ph/9605403 hep-ph/9603212 hep-ph/9710441 Electroweak phase transitions in the secluded arXiv:0912.5069 [ [ [ [ Prog. Theor. Phys. √ arXiv:0705.4117 ]. 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