230 research outputs found
Study of dark matter physics in non-universal gaugino mass scenario
We study dark matter physics in the Minimal Supersymmetric Standard Model
with non-universal gaugino masses at the unification scale. In this scenario,
the specific ratio of wino and gluino masses realizes the electro-weak scale
naturally and achieves 125 GeV Higgs boson mass. Then, relatively light
higgsino is predicted and the lightest neutral particle, that is dominantly
given by the neutral component of higgsino, is a good dark matter candidate.
The direct detection of the dark matter is sensitive to not only a higgsino
mass but also gaugino masses significantly. The upcoming XENON1T experiment
excludes the parameter region where bino or gluino is lighter than about 2.5
TeV if the higgsino and the gaugino mass parameters have same signs. We see
that the direct detection of dark matter gives stronger bound than the direct
search at the LHC experiment when higgsino sizably contributes to the dark
matter abundanceComment: 21 pages, 5 figures, 1 tabl
Status of the semileptonic decays and muon g-2 in general 2HDMs with right-handed neutrinos
In this paper, we study the extended Standard Model (SM) with an extra Higgs
doublet and right-handed neutrinos. If the symmetry to distinguish the two
Higgs doublets is not assigned, flavor changing neutral currents (FCNCs)
involving the scalars are predicted even at the tree level. We investigate the
constraints on the FCNCs at the one-loop level, and especially study the
semileptonic meson decays, e.g. and processes, where the SM predictions are more than away from the
experimental results. We also consider the flavor-violating couplings involving
right-handed neutrinos and discuss if the parameters to explain the excesses of
the semileptonic decays can resolve the discrepancy in the the anomalous
muon magnetic moment. Based on the analysis, we propose the smoking-gun signals
of our model at the LHC.Comment: 33 pages, 21 figures, final version published in JHE
LHC phenomenology of natural MSSM with non-universal gaugino masses at the unification scale
In this letter, we study collider phenomenology in the supersymmetric
Standard Model with a certain type of non-universal gaugino masses at the gauge
coupling unification scale, motivated by the little hierarchy problem. In this
scenario, especially the wino mass is relatively large compared to the gluino
mass at the unification scale, and the heavy wino can relax the fine-tuning of
the higgsino mass parameter, so-called -parameter. Besides, it will
enhance the lightest Higgs boson mass due to the relatively large left-right
mixing of top squarks through the renormalization group (RG) effect. Then
GeV Higgs boson could be accomplished, even if the top squarks are lighter than
TeV and the parameter is within a few hundreds GeV. The right-handed
top squark tends to be lighter than the other sfermions due to the RG runnings,
then we focus on the top squark search at the LHC. Since the top squark is
almost right-handed and the higgsinos are nearly degenerate, channel is the most sensitive to this scenario. We figure out current
and expected experimental bounds on the lightest top squark mass and model
parameters at the gauge coupling unification scale.Comment: 15 pages, 5 figures, 1 table; added references and clarification
Top Forward-backward asymmetry at the Tevatron vs. Charge asymmetry at the LHC in chiral models with flavored Higgs fields
An extra model with coupled only to the right-handed (RH)
up-type quarks has been one of the popular models for the Tevatron top
forward-backward asymmetry (FBA), and has been excluded by the same-sign
top-pair productions at the LHC. However, the original model is not
physical, since the up-type quarks are massless including the top quark. This
disaster can be evaded if the Higgs sector is extended by including new Higgs
doublets with nonzero charges. We find that some parameter regions
could achieve not only the top FBA at the Tevatron, but also the charge
asymmetry at the LHC without exceeding the upper limit of the same-sign
top-quark pair production at the LHC. The lesson is that it is mandatory to
extend the Higgs sector whenever one considers chiral gauge symmetries beyond
the SM gauge group. Otherwise some fermions remain massless, and thus it is
meaningless to work on phenomenology without the extra Higgs doublets with new
chiral gauge charges.Comment: Contribution to HCP2012 Proceedin
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