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1. chinaXiv:201711.02262 [pdf]

Status of Natural Supersymmetry from the GmSUGRA in Light of the current LHC Run-2 and LUX data

Waqas Ahmed; Xiao-Jun Bi; Tianjun Li; Jia Shu Niu; Shabbar Raza; Qian-Fei Xiang; Peng-Fei Yin
Subjects: Physics >> General Physics: Statistical and Quantum Mechanics, Quantum Information, etc.

We study natural supersymmetry in the Generalized Minimal Supergravity (GmSUGRA).For the parameter space with low energy electroweak fine-tuning measures less than 50, we are left with only the Z-pole, Higgs-pole and Higgsino LSP scenarios for dark matter (DM). We perform the focused scans for such parameter space and find that it satisfies various phenomenological constraints and is compatible with the current direct detection bound on neutralino DM reported by the LUX experiment. Such parameter space also has solutions with correct DM relic density besides the solutions with DM relic density smaller or larger than 5 WMAP9 bounds. We present five benchmark points as examples. In these benchmark points, gluino and the first two generations of squarks are heavier than 2 TeV, stop ?t1,2 are in the mass range [1, 2] TeV, while sleptons are lighter than 1 TeV. Some part of the parameter space can explain the muon anomalous magnetic moment within 3 as well. We also perform the collider study of such solutions by implementing and comparing with relevant studies done by the ATLAS and CMS Collaborations. We find that the points with Higgsino dominant ? 02/ ? ±1 mass upto 300 GeV are excluded in Z-pole scenario while for Higgs-pole scenario, the points with ? 02 mass up to 460 GeV are excluded. We also notice that the Higgsino LSP points in our present scans are beyond the reach of present LHC searches. Next, we show that for both the Z-pole and Higgs-pole scenarios, the points with electroweak fine-tuning measure around 20 do still survive.

submitted time 2017-11-10 Hits1878Downloads1006 Comment 0

2. chinaXiv:201609.01062 [pdf]

The 750 GeV diphoton excess at the LHC and dark matter constraints

Xiao-Jun Bi; Qian-Fei Xiang; Peng-Fei Yin; Zhao-Huan Yu
Subjects: Physics >> Nuclear Physics

The recent reported 750 GeV diphoton excess at the 13 TeV LHC is explained in the framework of effective field theory assuming the diphoton resonance is a scalar (pseudoscalar) particle. It is found that the large production rate and the broad width of this resonance are hard to simultaneously explain if only visible final states are considered. Therefore an invisible decay channel to dark matter (DM) is strongly favored by the diphoton excess with a broad width, given a large coupling of the new scalar to DM. We set constraints on the parameter space in this scenario using the results from LHC Run 1, DM relic density, and DM direct and indirect detection experiments. We find that the DM searches can exclude a large portion of the parameter regions accounting for the diphoton excess with a broad width.

submitted time 2016-09-19 Hits2516Downloads1070 Comment 0

3. chinaXiv:201609.00889 [pdf]

Searches for dark matter signals in simplified models at future hadron colliders

Qian-Fei Xiang; Xiao-Jun Bi; Peng-Fei Yin; Zhao-Huan Yu
Subjects: Physics >> Nuclear Physics

We study the prospect of dark matter (DM) searches in the monojet channel at future?pp?colliders with center-of-mass energies of 33, 50, and 100~TeV. We consider a class of simplified models in which a vector boson connecting DM particles to quarks is introduced. Comparing with studies in the effective field theory, the present framework gives more reasonable production rates and kinematics of the DM signatures. We estimate the sensitivities of future colliders with an integrated luminosity of 3?ab?1?to the DM-induced monojet signature and show the parameter space that can be explored. The constraints from direct and indirect DM detection experiments are compared with the future collider sensitivities. We find that the future collider detection will be much more sensitive than the indirect detection for the vector interaction, and have better sensitivities than those of the direct detection by several orders of magnitude for the axial vector interaction.

submitted time 2016-09-13 Hits1439Downloads782 Comment 0

4. chinaXiv:201609.00085 [pdf]

Equation of state and hybrid star properties with the weakly interacting light U-boson in relativistic models

Dong-Rui Zhang; Wei-Zhou Jiang; Si-Na Wei; Rong-Yao Yang; Qian-Fei Xiang
Subjects: Physics >> Nuclear Physics

It has been a puzzle whether quarks may exist in the interior of massive neutron stars, since the hadron-quark phase transition softens the equation of state (EOS) and reduce the neutron star (NS) maximum mass very significantly. In this work, we consider the light U-boson that increases the NS maximum mass appreciably through its weak coupling to fermions. The inclusion of the U-boson may thus allow the existence of the quark degrees of freedom in the interior of large mass neutron stars. Unlike the consequence of the U-boson in hadronic matter, the stiffening role of the U-boson in the hybrid EOS is not sensitive to the choice of the hadron phase models. In addition, we have also investigated the effect of the effective QCD correction on the hybrid EOS. This correction may reduce the coupling strength of the U-boson that is needed to satisfy NS maximum mass constraint. While the inclusion of the U-boson also increases the NS radius significantly, we find that appropriate in-medium effects of the U-boson may reduce the NS radii significantly, satisfying both the NS radius and mass constraints well.

submitted time 2016-09-06 Hits841Downloads496 Comment 0

5. chinaXiv:201609.00074 [pdf]

Searching for Singlino-Higgsino Dark Matter in the NMSSM

Qian-Fei Xiang; Xiao-Jun Bi; Peng-Fei Yin; Zhao-Huan Yu
Subjects: Physics >> Nuclear Physics

We study a simplified scenario in the next-to-minimal supersymmetric standard model with a split electroweak spectrum, in which only the singlino and higgsinos are light and other superpartners are decoupled. Serving as a dark matter candidate, a singlino-dominated neutralino?χ~01?should have either resonant annihilation effects or sizable higgsino components to satisfy the observed relic abundance. The sensitivities of LHC searches and dark matter detection experiments are investigated. With an integrated luminosity of?30(300)fb?1,?$3l + \missET$?and?$2l + \missET$?searches at the 13 (14) TeV LHC are expected to reach up to?$m_{\chia}\sim 150 (270) \mathrm{GeV}$?and?mχ~02,χ~±1?320(500)GeV. Near future dark matter direct and indirect detection experiments can cover some parameter regions where collider searches lose their sensitivities.

submitted time 2016-09-06 Hits1161Downloads692 Comment 0

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