7,693 research outputs found
Status and prospects of light bino-higgsino dark matter in natural SUSY
Given the recent progress in dark matter direction detection experiments, we
examine a light bino-higgsino dark matter (DM) scenario ( GeV and
GeV) in natural supersymmetry with the electroweak fine tuning
measure . By imposing various constraints, we note that: (i)
For , the parameter space allowed by the DM relic density and
collider bounds can almost be excluded by the very recent spin-independent (SI)
scattering cross section limits from the XENON1T (2017) experiment. (ii) For
, the SI limits can be evaded due to the cancelation effects
in the coupling, while rather stringent
constraints come from the PandaX-II (2016) spin-dependent (SD) scattering cross
section limits, which can exclude the higgsino mass and the LSP mass
up to about 230 GeV and 37 GeV, respectively.
Furthermore, the surviving parameter space will be fully covered by the
projected XENON1T experiment or the future trilepton searches at the HL-LHC.Comment: 15 pages, 4 figures, discussions and references added, accepted by
EPJ
Higgs pair production with SUSY QCD correction: revisited under current experimental constraints
We consider the current experimental constraints on the parameter space of
the MSSM and NMSSM. Then in the allowed parameter space we examine the Higgs
pair production at the 14 TeV LHC via ( is the 125 GeV
SM-like Higg boson) with one-loop SUSY QCD correction and compare it with the
production via . We obtain the following observations: (i) For the
MSSM the production rate of can reach 50 fb and thus can be
competitive with , while for the NMSSM has a much
smaller rate than due to the suppression of the
coupling; (ii) The SUSY-QCD correction to is sizable, which
can reach for the MSSM and for the NMSSM within the
region of the Higgs data; (iii) In the heavy SUSY limit (all soft mass
parameters become heavy), the SUSY effects decouple rather slowly from the
Higgs pair production (especially the process), which, for TeV and TeV, can enhance the production rate by a factor of
1.5 and 1.3 for the MSSM and NMSSM, respectively. So, the Higgs pair production
may be helpful for unraveling the effects of heavy SUSY.Comment: discussions and references added, accepted by JHE
Explaining 750 GeV diphoton excess from top/bottom partner cascade decay in two-Higgs-doublet model extension
In this paper, we interpret the 750 GeV diphoton excess in the Zee-Babu
extension of the two-Higgs-doublet model by introducing a top partner
()/bottom partner (). In the alignment limit, the 750 GeV resonance is
identified as the heavy CP-even Higgs boson (), which can be sizably
produced via the QCD process or followed by
the decay or . The diphoton decay rate of is greatly
enhanced by the charged singlet scalars predicted in the Zee-Babu extension and
the total width of can be as large as 7 GeV. Under the current LHC
constraints, we scan the parameter space and find that such an extension can
account for the observed diphoton excess.Comment: 19 pages, 4 figures; some discussions and references adde
A light SUSY dark matter after CDMS-II, LUX and LHC Higgs data
In SUSY, a light dark matter is usually accompanied by light scalars to
achieve the correct relic density, which opens new decay channels of the SM
like Higgs boson. Under current experimental constraints including the latest
LHC Higgs data and the dark matter relic density, we examine the status of a
light neutralino dark matter in the framework of NMSSM and confront it with the
direct detection results of CoGeNT, CDMS-II and LUX. We have the following
observations: (i) A dark matter as light as 8 GeV is still allowed and its
scattering cross section off the nucleon can be large enough to explain the
CoGeNT/CDMS-II favored region; (ii) The LUX data can exclude a sizable part of
the allowed parameter space, but still leaves a light dark matter viable; (iii)
The SM-like Higgs boson can decay into the light dark matter pair with an
invisible branching ratio reaching 30% under the current LHC Higgs data, which
may be tested at the 14 TeV LHC experiment.Comment: 18 pages, 4 figure
Top quark forward-backward asymmetry at the Tevatron: a comparative study in different new physics models
The top quark forward-backward asymmetry A_{FB}^t measured at the Tevatron is
above the Standard Model prediction by more than 2-sigma deviation, which might
be a harbinger for new physics. In this work we examine the contribution to
A_{FB}^t in two different new physics models: one is the minimal supersymmetric
model without R-parity (RPV-MSSM) which contributes to A_{FB}^t via
sparticle-mediated t-channel process d d_bar-> t t_bar; the other is the
third-generation enhanced left-right model (LR model) which contributes to
A_{FB}^t via Z'-mediated t-channel or s-channel processes. We find that in the
parameter space allowed by the tt_bar production rate and the tt_bar invariant
mass distribution at the Tevatron, the LR model can enhance A_{FB}^t to within
the 2-sigma region of the Tevatron data for the major part of the parameter
space, and in optimal case A_{FB}^t can reach 12% which is slightly below the
1-sigma lower bound. For the RPV-MSSM, only in a narrow part of the parameter
space can the \lambda'' couplings enhance A_{FB}^t to within the 2-sigma region
while the \lambda' couplings just produce negative contributions to worsen the
fit.Comment: Version in PRD (RPV-MSSM lambda" effects added
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