Leptophobic Z in Supersymmetry and Where to Find Them
563
Fig. 2 Plot shows leptophobic Z mass versus production cross section and dijet branching ratio
with corresponding acceptance rate. The dashed line shows the USM sample, which assumes that
Z can only decay through the SM particles, and the dotted line shows UMSSM, including all
supersymmetric particles. Error bars include scale and PDF variations as well as the variation in
the dijet decay rate per sample. The CMS limit is taken from [3]
which requires sin χ ∼ = (−1) n+1 0.3, assuming g /g 1 =
√
5/3 ratio is satisfied at Z
mass scale.
Such leptophobic Z can only be bounded via high-mass dijet searches. It has
been shown, in [3], that these bounds are much weaker compared to Drell–Yan
signature. In Fig. 2 we performed a similar comparison as above where this time the
leptophobic Z mass varied to compare with CMS collaboration’s dijet limits [3]. In
order to zoom into the respectively low mass region, we varied Z mass between 1
and 3.5 TeV and plotted against the multiplication of its production cross section,
branching ratio to dijet final states and the acceptance rate stated in [3]. Again, the
dashed line assumes that Z can only decay to the SM particles (USM) and dotted
line includes its possible decay channels to SUSY particles as well (UMSSM). In
addition to the theoretical uncertainties, the error bars also show the variation in the
total decay rate to dijet final states. Such construction reduces the Z mass limits
to 1.6 TeV and creates a considerably large deviation between USM and UMSSM
depending on the dijet branching fraction.
3 Leptophobic Z in HL- & HE-LHC
A leptophobic Z can still be observed through leptonic final states, but instead of
direct decays, leptons can be produced through a cascade decay of supersymmetric
particles. In Fig. 3, we proposed a possible scenario where two charginos are pair
produced via on-shell Z and they further decay into missing energy and dileptons
through W . Such scenario might generate its background through heavy Higgs
production and their decay to charginos. However, we observed that the branching
fraction of such decay is negligible compared to heavy Z boson’s decay rate. Also,
neutralino pair production or chargino-neutralino associative production through
Z has been observed to have small branching fraction compared to chargino pair
production. To test this hypothesis, we choose two UMSSM benchmarks to study
possible observability of such leptophobic scenarios. Following [11], we chose two
benchmarks using Eq. (1), where for BM I n chosen to be 0 and for BM II n chosen
to be 1. A conservative, 2.5 TeV Z mass has been chosen for both benchmarks
563
Fig. 2 Plot shows leptophobic Z mass versus production cross section and dijet branching ratio
with corresponding acceptance rate. The dashed line shows the USM sample, which assumes that
Z can only decay through the SM particles, and the dotted line shows UMSSM, including all
supersymmetric particles. Error bars include scale and PDF variations as well as the variation in
the dijet decay rate per sample. The CMS limit is taken from [3]
which requires sin χ ∼ = (−1) n+1 0.3, assuming g /g 1 =
√
5/3 ratio is satisfied at Z
mass scale.
Such leptophobic Z can only be bounded via high-mass dijet searches. It has
been shown, in [3], that these bounds are much weaker compared to Drell–Yan
signature. In Fig. 2 we performed a similar comparison as above where this time the
leptophobic Z mass varied to compare with CMS collaboration’s dijet limits [3]. In
order to zoom into the respectively low mass region, we varied Z mass between 1
and 3.5 TeV and plotted against the multiplication of its production cross section,
branching ratio to dijet final states and the acceptance rate stated in [3]. Again, the
dashed line assumes that Z can only decay to the SM particles (USM) and dotted
line includes its possible decay channels to SUSY particles as well (UMSSM). In
addition to the theoretical uncertainties, the error bars also show the variation in the
total decay rate to dijet final states. Such construction reduces the Z mass limits
to 1.6 TeV and creates a considerably large deviation between USM and UMSSM
depending on the dijet branching fraction.
3 Leptophobic Z in HL- & HE-LHC
A leptophobic Z can still be observed through leptonic final states, but instead of
direct decays, leptons can be produced through a cascade decay of supersymmetric
particles. In Fig. 3, we proposed a possible scenario where two charginos are pair
produced via on-shell Z and they further decay into missing energy and dileptons
through W . Such scenario might generate its background through heavy Higgs
production and their decay to charginos. However, we observed that the branching
fraction of such decay is negligible compared to heavy Z boson’s decay rate. Also,
neutralino pair production or chargino-neutralino associative production through
Z has been observed to have small branching fraction compared to chargino pair
production. To test this hypothesis, we choose two UMSSM benchmarks to study
possible observability of such leptophobic scenarios. Following [11], we chose two
benchmarks using Eq. (1), where for BM I n chosen to be 0 and for BM II n chosen
to be 1. A conservative, 2.5 TeV Z mass has been chosen for both benchmarks