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SUSY dark matter in light of CDMS II results: a comparative study for different models

Cao, Junjie; Hikasa, Ken-ichi; Wang, Wenyu; Yang, Jin Min; Yu, Li-XinSubjects: Physics >> The Physics of Elementary Particles and Fields

We perform a comparative study of the neutralino dark matter scattering on nucleon in three popular supersymmetric models: the minimal (MSSM), the next-to-minimal (NMSSM) and the nearly minimal (nMSSM). First, we give the predictions of the elastic cross section by scanning over the parameter space allowed by various direct and indirect constraints, which are from the measurement of the cosmic dark matter relic density, the collider search for Higgs boson and sparticles, the precision electroweak measurements and the muon anomalous magnetic moment. Then we demonstrate the property of the allowed parameter space with/without the new limits from CDMS II. We obtain the following observations: (i) For each model the new CDMS limits can exclude a large part of the parameter space allowed by current collider constraints; (ii) The property of the allowed parameter space is similar for MSSM and NMSSM, but quite different for nMSSM; (iii) For each model the future SuperCDMS can cover most of the allowed parameter space given that all soft breaking parameters are below 1 TeV. |

submitted time
2016-05-15
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Light dark matter in NMSSM and implication on Higgs phenomenology

Cao, Junjie; Hikasa, Ken-ichi; Wang, Wenyu; Yang, Jin MinSubjects: Physics >> The Physics of Elementary Particles and Fields

For the experimental search of neutralino dark matter, it is important to know its allowed mass and scattering cross section with the nucleon. In order to figure out how light a neutralino dark matter can be predicted in low energy supersymmetry, we scan over the parameter space of the NMSSM (next-to-minimal supersymmetric model), assuming all the relevant soft mass parameters to be below TeV scale. We find that in the parameter space allowed by current experiments the neutralino dark matter can be as light as a few GeV and its scattering rate off the nucleon can reach the sensitivity of XENON100 and CoGeNT. As a result, a sizable parameter space is excluded by the current XENON100 and CoGeNT data (the plausible CoGeNT dark matter signal can also be explained). The future 6000 kg-days exposure of XENON100 will further explore (but cannot completely cover) the remained parameter space. Moreover, we find that in such a light dark matter scenario a light CP-even or CP-odd Higgs boson must be present to satisfy the measured dark matter relic density. Consequently, the SM-like Higgs boson h(SM) may decay predominantly into a pair of light Higgs bosons or a pair of neutralinos so that the conventional decays like h(SM) -> gamma gamma is much suppressed. (C) 2011 Elsevier B.V. All rights reserved. |

submitted time
2016-05-14
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Current experimental bounds on stop mass in natural SUSY

Han, Chengcheng; Hikasa, Ken-ichi; Wu, Lei; Yang, Jin Min; Zhang, YangSubjects: Physics >> The Physics of Elementary Particles and Fields

Motivated by the recent progress of direct search for the productions of stop pair and sbottom pair at the LHC, we examine the constraints of the search results on the stop ( (t) over tilde (1)) mass in natural SUSY. We first scan the parameter space of natural SUSY in the framework of MSSM, considering the constraints from the Higgs mass, B-physics and electroweak precision measurements. Then in the allowed parameter space we perform a Monte Carlo simulation for stop pair production followed by (t) over tilde (1). t (chi) over tilde (0)(1) or (t) over tilde (1). b (chi) over tilde (+)(1) and sbottom pair production followed by (b) over tilde (1) -> b (chi) over tilde (0)(1) or (b) over tilde (1) -> t (chi) over tilde (-)(1). Using the combined results of ATLAS with 20.1 fb(-1) from the search of l + jets + (sic)(T), hadronic t (t) over bar + (sic)(T) and 2b + (sic)(T), we find that a stop lighter than 600 GeV can be excluded at 95% CL in this scenario. |

submitted time
2016-05-09
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Subjects: Physics >> The Physics of Elementary Particles and Fields

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 (T)/bottom partner (B). In the alignment limit, the 750 GeV resonance is identified as the heavy CP-even Higgs boson (H), which can be sizably produced via the QCD process pp -> T (T) over bar or pp -> B (B) over bar followed by the decay T -> Ht or B -> Hb. The diphoton decay rate of His greatly enhanced by the charged singlet scalars predicted in the Zee-Babu extension and the total width of H 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. (C) 2016 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY license. |

Collider signatures of Higgs-portal scalar dark matter

Han, Huayong; Yang, Jin Min; Zhang, Yang; Zheng, SiboSubjects: Physics >> The Physics of Elementary Particles and Fields

In the simplest Higgs-portal scalar dark matter model, the dark matter mass has been restricted to be either near the resonant mass (m(h)/2) or in a large-mass region by the direct detection at LHC Run 1 and LUX. While the large-mass region below roughly 3 TeV can be probed by the future Xenon1T experiment, most of the resonant mass region is beyond the scope of Xenon1T. In this paper, we study the direct detection of such scalar dark matter in the narrow resonant mass region at the 14 TeV LHC and the future 100 TeV hadron collider. We show the luminosities required for the 2 sigma exclusion and 5 sigma discovery. (C) 2016 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY license. |

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