分类： 物理学 分类： 物理学 >> 基本粒子与场物理学 提交时间： 2016-12-28
摘要： In a topcolor-assisted technicolor model (TC2) with large FCNC top quark couplings, we study its correlated contributions to the top quark forward-backward asymmetry (AF B ) at the Tevatron, the top charge asymmetry (AC) and the triple-top production at the LHC. Under current constraints on the top quark from the LHC and Tevatron (such as the total and differential production rates), we scan the parameter space of such a TC2 model. We find that in the allowed parameter space the TC2 model can explain the Tevatron measured AFB at 2σ level, but meanwhile significantly enhance AC at the LHC. Such enhanced AC, albeit currently allowed by the LHC measurement at 2σ level, will serve as a test of TC2 with the improvement of measurement precision at the LHC. Then with all the constraints (including the requirement to explain AF B at 2σ level and satisfying the current LHC measurement of AC at 2σ level), we find that the TC2 model can induce sizable triple-top production at the 14 TeV LHC (the production rate can maximally reach 16 pb). Due to the low SM backgrounds, the triple-top production can also be a good probe for TC2 model, complementary to AC.
分类： 物理学 分类： 物理学 >> 基本粒子与场物理学 提交时间： 2016-12-28
摘要： We consider the natural supersymmetry scenario in the framework of the R-parity conserving minimal supersymmetric standard model (called natural MSSM) and examine the observability of stop pair production at the LHC. We first scan the parameters of this s
分类： 物理学 分类： 物理学 >> 基本粒子与场物理学 提交时间： 2016-12-28
摘要： The excess of top quark forward-backward asymmetry (AtFBAFBtA^t_{FB}) reported by the Tevatron and the enhancement of the Higgs decay to diphoton observed by the LHC may point to a same origin of new physics. In this note we examined such anomalies in the
分类： 物理学 分类： 物理学 >> 基本粒子与场物理学 提交时间： 2016-12-28
摘要： We propose a realistic 5D orbifold GUT model that can reduce to natural (or radiative natural) supersymmetry as the low energy effective theory. Supersymmetry as well as gauge symmetry are broken by the twist boundary conditions. We find that it is non-trivial to introduce other flavor symmetry other than the SU(2)R R-symmetry. We ameliorate the tension between the small number of free parameters and the successful electroweak symmetry breaking by introducing non-minimal Kahler potentials. A large trilinear term At, which is necessary to give a 125 GeV Higgs boson, is naturally provided in our scenario. A scan under current experimental constraints shows that our model can realize natural (or radiative natural) supersymmetry. Only radiative natural supersym- metry can naturally lead to 125 GeV higgs. Additional dark matter species other than neutralino(like axion) are needed to provide enough relic density. Relatively large stop masses are necessary to give realistic higg mass in most of the parameter spaces.
分类： 物理学 分类： 物理学 >> 基本粒子与场物理学 提交时间： 2016-12-28
摘要： 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 bb?→hhbb?→hhb\bar{b}\to hh (hhh is the 125 GeV SM-like Higg boson
分类： 物理学 分类： 物理学 >> 基本粒子与场物理学 提交时间： 2016-12-28
摘要： 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 ̃ ) 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 ̃ → tχ ̃0 or t ̃ → bχ ̃+ and sbottom pair production followed by ̃b → bχ ̃0 or ̃b → tχ ̃−. 1111 1111 Using the combined results of ATLAS with 20.1 fb−1 from the search of l + jets + E/ T , hadronic tt ̄+E/T and 2b+E/T, we find that a stop lighter than 600 GeV can be excluded at 95% CL in this scenario.
分类： 物理学 分类： 物理学 >> 基本粒子与场物理学 提交时间： 2016-12-28
摘要： In the Next-to-Minimal Supersymemtric Standard Model (NMSSM), one of the neutral Higgs scalars (CP-even or CP-odd) may be lighter than half of the SM-like Higgs boson. In this case, the SM-like Higgs boson h can decay into such a light scalar pair and con
分类： 物理学 分类： 物理学 >> 基本粒子与场物理学 提交时间： 2016-12-28
摘要： We investigate a strategy to search for light, nearly degenerate higgsinos within the natural MSSM at the LHC. We demonstrate that the higgsino mass range μμ\mu in 100?150100?150100-150 GeV, which is preferred by the naturalness, can be probed at 2σ2σ2\si
分类： 物理学 分类： 物理学 >> 基本粒子与场物理学 提交时间： 2016-12-28
摘要： 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 m
分类： 物理学 分类： 物理学 >> 基本粒子与场物理学 提交时间： 2016-12-28
摘要： In light of the Higgs discovery and the nonobservation of sparticles at the LHC, we revisit the supersymmetric theory (SUSY) induced top quark flavor-changing decay into the Higgs boson. We perform a scan over the relevant SUSY parameter space by consider
分类： 物理学 分类： 物理学 >> 基本粒子与场物理学 提交时间： 2016-12-28
摘要： In some supersymmetric models like split supersymmetry or models with non-universal gaugino mass, bino (LSP) and winos (NLSP) may have rather small mass splitting in order to provide the correct dark matter relic density through bino/wino co-annihilation. Such a scenario with the compressed bino/wino is difficult to explore at the LHC. In this work we propose to probe this scenario from pp → jχ ̃02χ ̃±1 followed by χ ̃02 → γχ ̃01 and χ ̃±1 → W∗χ ̃01 → l±νχ ̃01 (this method is also applicable to the compressed bino/higgsino scenario). Through a detailed Monte Carlo simulation for both the signal and the backgrounds, we find that for a mass splitting ∆M ∼ 5 − 15 GeV between bino (LSP) and wino (NLSP), the 14 TeV LHC with luminosity of 500fb−1 can probe the wino up to 150 GeV (the sensitivity can reach 5σ for ∆M = 5 GeV and 2σ for ∆M = 15 GeV). We also investigate the dark matter detection sensitivities for this scenario and find that the planned XENON-1T(2017) cannot fully cover the parameter space with wino below 150 GeV allowed by relic density and the LUX limits.
分类： 物理学 分类： 物理学 >> 基本粒子与场物理学 提交时间： 2016-12-28
摘要： Considering the constraints from collider experiments and dark matter detection, we investigate the SUSY effects in the Higgs production channels e(+) e(?) → Zh at an e(+) e(?) collider with a center-of-mass energy above 240 GeV and γγ → h → bb? at a phot
分类： 物理学 分类： 物理学 >> 基本粒子与场物理学 提交时间： 2016-12-28
摘要： The evidence of a new scalar particle X from the 750 GeV diphoton excess, and the absence of any other signal of new physics at the LHC so far suggest the existence of new colored scalars, which may be moderately light and thus can induce sizable Xgg and
分类： 物理学 分类： 物理学 >> 基本粒子与场物理学 提交时间： 2016-12-27
摘要： We utilize the recent LHC-13 TeV data to study the lower mass bound on top-squark (stop) in natural supersymmetry. We recast the LHC sparticle inclusive search of (≥1)jets+EmissT(≥1)jets+ETmiss(\ge 1){\rm jets} + E^{miss}_T with αTαT\alpha_T variable, the
分类： 物理学 分类： 物理学 >> 基本粒子与场物理学 提交时间： 2016-12-27
摘要： Motivated by the latest results of the LHC Run-2 and LUX experiments, we examine the status of the constrained minimal supersymmetric standard model (CMSSM) by performing a global fit. We construct a likelihood function including the electroweak precision
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