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J. Y. Araz
and CMS collaboration [3] around 2.7 TeV for 12.9 fb −1 . In case of dilepton
resonance studies, ATLAS collaboration presented the mass bounds at 3.8–4.1 TeV
for 36.1 fb −1 [2] and CMS collaboration presented at 3.5 TeV for 13 fb −1 integrated
luminosity. 1 We investigate possible loopholes within the specific scenarios to lower
these mass limits and also propose a leptophobic framework for Z to search for a
possible signal through supersymmetric decay channels in HL- & HE-LHC.
The rest of this report is organised as follows; in Sect. 2, we introduced the
theoretical properties of UMSSM and discussed current mass bounds on Z at the
time when this study conducted. In the following Sect. 3, we discussed possible
supersymmetric signatures to observe a leptophobic Z in HL- & HE-LHC and
finally we conclude in Sect. 4.
2 Theoretical Framework and Z Mass Bounds
Within a possible minimal representation in supersymmetry (SUSY), Z bosons can
arise from the breaking of rank-6, E 6 group, which is greatly motivated by Grand
Unified Theories. Among the various possible breaking schemes of E 6 exceptional
group, the so-called UMSSM framework being the U(1) extended MSSM, arises
from the breaking through SO(10). The two-step breaking structure creates separate
U(1) gauge groups [8–10]
E 6 → SO(10) ⊗ U(1) ψ → (SU (5) ⊗ U(1) χ ) ⊗ U(1) ψ ,
where these U(1)’s can mix via θ E 6 angle and generate U(1) ,
U(1)
= U(1) ψ cos θ E 6 − U(1) χ sin θ E 6 .
Here SU (5) group further breaks into MSSM gauge structure. Alongside with
such vector boson, extending MSSM framework with a U(1) gauge provides an
anomaly free gauge structure. This can prevent the R-parity violating terms from
the Lagrangian and eliminates short-lived proton possibility which occurs due to
SU (5) breaking.
In E 6 , the matter sector of UMSSM arises from the breaking of 27-plet vector
representation in to 16 ⊕ 10 ⊕ 1, where 16 further decomposes to the matter
fields, 10 to electroweak Higgs fields and exotic quarks and singlet, 1, becomes
U(1) singlet superfield, S. In addition to the MSSM’s large particle content,
UMSSM accommodates extended slepton, sneutrino, and squark sector up to 6
supersymmetric particles in each family. Also, breaking SO(10)’s 16-plet vector
representation provides a right-handed neutrino superfield which generates right1 It is important to note that these limits are recently updated. See [6] for dijet resonances at
137 fb −1 and [7] for dilepton resonances at 139 fb −1 .
J. Y. Araz
and CMS collaboration [3] around 2.7 TeV for 12.9 fb −1 . In case of dilepton
resonance studies, ATLAS collaboration presented the mass bounds at 3.8–4.1 TeV
for 36.1 fb −1 [2] and CMS collaboration presented at 3.5 TeV for 13 fb −1 integrated
luminosity. 1 We investigate possible loopholes within the specific scenarios to lower
these mass limits and also propose a leptophobic framework for Z to search for a
possible signal through supersymmetric decay channels in HL- & HE-LHC.
The rest of this report is organised as follows; in Sect. 2, we introduced the
theoretical properties of UMSSM and discussed current mass bounds on Z at the
time when this study conducted. In the following Sect. 3, we discussed possible
supersymmetric signatures to observe a leptophobic Z in HL- & HE-LHC and
finally we conclude in Sect. 4.
2 Theoretical Framework and Z Mass Bounds
Within a possible minimal representation in supersymmetry (SUSY), Z bosons can
arise from the breaking of rank-6, E 6 group, which is greatly motivated by Grand
Unified Theories. Among the various possible breaking schemes of E 6 exceptional
group, the so-called UMSSM framework being the U(1) extended MSSM, arises
from the breaking through SO(10). The two-step breaking structure creates separate
U(1) gauge groups [8–10]
E 6 → SO(10) ⊗ U(1) ψ → (SU (5) ⊗ U(1) χ ) ⊗ U(1) ψ ,
where these U(1)’s can mix via θ E 6 angle and generate U(1) ,
U(1)
= U(1) ψ cos θ E 6 − U(1) χ sin θ E 6 .
Here SU (5) group further breaks into MSSM gauge structure. Alongside with
such vector boson, extending MSSM framework with a U(1) gauge provides an
anomaly free gauge structure. This can prevent the R-parity violating terms from
the Lagrangian and eliminates short-lived proton possibility which occurs due to
SU (5) breaking.
In E 6 , the matter sector of UMSSM arises from the breaking of 27-plet vector
representation in to 16 ⊕ 10 ⊕ 1, where 16 further decomposes to the matter
fields, 10 to electroweak Higgs fields and exotic quarks and singlet, 1, becomes
U(1) singlet superfield, S. In addition to the MSSM’s large particle content,
UMSSM accommodates extended slepton, sneutrino, and squark sector up to 6
supersymmetric particles in each family. Also, breaking SO(10)’s 16-plet vector
representation provides a right-handed neutrino superfield which generates right1 It is important to note that these limits are recently updated. See [6] for dijet resonances at
137 fb −1 and [7] for dilepton resonances at 139 fb −1 .