分类： 物理学 >> 基本粒子与场物理学 提交时间： 2016-05-14
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 scenario under various experimental constraints, including the SM-like Higgs boson mass, the indirect limits from precision electroweak data and B-decays. Then in the allowed parameter space we study the stop pair production at the LHC followed by the stop decay into a top quark plus a lightest neutralino or into a bottom quark plus a chargino. From detailed Monte Carlo simulations of the signals and backgrounds, we find the two decay modes are complementary to each other in probing the stop pair production, and the LHC with root s = 14 TeV and 100 fb(-1) luminosity is capable of discovering the stop predicted in natural MSSM up to 450 GeV. If no excess events were observed at the LHC, the 95% C.L. exclusion limits of the stop masses can reach around 537 GeV.
分类： 生物学 >> 生物物理学 提交时间： 2016-05-12
Yuan, Shanshan
Zhang, Yang
Liu, Yalei
Yu, Nan
Zhang, Hong
Lu, Guizhi
Gao, Yanming
Gao, Ying
Guo, Xiaohui
Li, Qianqian
Huang, Chuncui
Wu, Hongmei
Li, Yan
摘要： Objective: Sera of Hashimoto's thyroiditis (HT) patients are known to exhibit elevated levels of anti-thyroglobulin IgG (TgAb IgG). Therefore, TgAb IgG represents a hallmark of this debilitating autoimmune disease. The aim of our study was to investigate the differential expression of specific glycosylation patterns of TgAb IgG from HT patients and healthy blood donors. Methods: HT patients (n = 32) were divided into two subgroups, medium level group (mHT, n = 15) and high level group (hHT, n = 17), according to the serum levels of TgAb detected by electrochemiluminescence immunoassay. TgAb IgG was purified by affinity chromatography from the sera of the HT group and control group (n = 15). MALDI-QIT-TOF-MS/MS spectrometry was performed to identify the glycosylation profiles of purified TgAb IgG. Lectin microarray technology was used to compare the abundance of different glycans found on TgAb IgG between HT patients and controls, and between the mHT and hHT groups. Results: The results by MALDI-QIT-TOF-MS/MS showed that the glycosylation profiles of TgAb IgG were similar between the mHT, hHT, and control groups. Furthermore, the lectin microarray showed that compared to the control group (all P < .001), there were higher levels present of (1) mannose (detected as lectin LCA, VFA, and MNA-M); (2) terminal sialic acid (detected as SNA-I and PSA); (3) core fucose (detected as LcH); and (4) Gal(beta 1-4) GlcNAc(beta 1-2) Man glycans (detected as PHA-L) on TgAb IgG from the HT group. A similar trend was observed between the hHT and mHT group, with elevated levels of mannose, terminal sialic acid, core fucose, and Gal(beta 1-4) GlcNAc(< 12) Man glycans on TgAb IgG found in the hHT group compared with the mHT group (all P < .05). Conclusions: TgAb IgG of HT patients exhibits higher glycosylation levels than those observed for TgAb IgG of healthy controls. Our results provide new clues for exploring the role of TgAb in the pathogenesis of HT.
分类： 物理学 >> 基本粒子与场物理学 提交时间： 2016-05-09
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) 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.
分类： 物理学 >> 基本粒子与场物理学 提交时间： 2016-05-09
摘要： The excess of top-quark forward-backward asymmetry (A(FB)(t)) reported by the Tevatron and the enhancement of the Higgs decay to diphoton observed at the LHC may point to a same origin of new physics. In this note we examined such anomalies in the two-Higgs-doublet model with a color-triplet scalar. We found that under current experimental constraints this model can simultaneously explain both anomalies at 1 sigma level. Also, we examined the Higgs decay h -> Z gamma and displayed its correlation with h -> gamma gamma. We found that unlike other models, this model predicts a special correlation between h -> Z gamma and h -> gamma gamma, i.e., the Z gamma rate is highly suppressed while the gamma gamma rate is enhanced. This behavior may help to distinguish this model in the future high luminosity run of the LHC.
分类： 物理学 >> 基本粒子与场物理学 提交时间： 2016-05-09
摘要： In some supersymmetric models like split supersymmetry or models with nonuniversal gaugino mass, 'bino [lightest sparticle (LSP)] and wino [next-to-lightest sparticle (NLSP)] may have rather small mass splitting in order to provide the correct dark matter relic density through bino/wino coannihilation. 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 -> j (chi) over tilde (0)(2)(chi) over tilde (+/-)(1) followed by (chi) over tilde (0)(2) -> gamma(chi) over tilde (0)(1) and (chi) over tilde (+/-)(1) -> W*(chi) over tilde (0)(1) -> l(+/-)nu(chi) over tilde (0)(1) (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 Delta M similar to 10-15 GeV between bino (LSP) and wino (NLSP), the 14 TeV LHC with a luminosity of 1000 fb(-1) can probe the wino up to 150 GeV (the sensitivity can reach 3.4 sigma for Delta M = 10 GeV and 2 sigma for Delta 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 a wino below 150 GeV allowed by relic density and the LUX limits.
分类： 物理学 >> 基本粒子与场物理学 提交时间： 2016-05-09
摘要： Recently the ATLAS collaboration reported a 3 sigma excess in the leptonic-Z + jets + E-T(miss) channel. This may be interpreted in the Next-to-Minimal Supersymmetric Standard Model (NMSSM) by gluino pair production with the decay chain (g) over tilde -> q (q) over bar(chi) over tilde (0)(2) -> q (q) over barZ (chi) over tilde (0)(1), where (chi) over tilde (0)(1) and (chi) over tilde (0)(2) denote the lightest and the next-to-lightest neutralinos with singlino and bino as their dominant components respectively. After exploring the relevant parameter space of the NMSSM by considering the constraints from the ATLAS searches for jets + E-T(miss) signals, we conclude that the NMSSM is able to explain the excess at 1 sigma level with the number of the signal events reaching its measured central value in optimal cases, and the best explanation comes from a compressed spectrum such as m((g) over tilde) similar or equal to 650 GeV, m((chi) over tilde2)(0) similar or equal to 565 GeV and m((chi) over tilde1)(0) similar or equal to 465 GeV. We also check the consistency of the ATLAS results with the null result of the CMS on-Z search. We find that under the CMS limits at 95% C.L., the event number of the ATLAS on-Z signal can still reach 11 in our scenario, which is about 1.2 sigma away from the measured central value.
分类： 物理学 >> 基本粒子与场物理学 提交时间： 2016-05-09
摘要： We propose a deflected anomaly mediation scenario from SUSY QCD which can lead to both positive and negative deflection parameters (there is a smooth transition between these two deflection parameter regions by adjusting certain couplings). Such a scenario can naturally give a SUSY spectrum in which all the colored sparticles are heavy while the sleptons are light. As a result, the discrepancy between the Brookheaven g(mu) - 2 experiment and LHC data can be reconciled in this scenario. We also find that the parameter space for explaining the g(mu) - 2 anomaly at 1 sigma level can be fully covered by the future LUX-ZEPLIN 7.2 Ton experiment.
分类： 物理学 >> 基本粒子与场物理学 提交时间： 2016-05-09
摘要： In the Next-to-Minimal Supersymmetric Standard Model (NMSSM), all singlet-dominated particles including one neutralino, one CP-odd Higgs boson and one CP-even Higgs boson can be simultaneously lighter than about 100 GeV. Consequently, dark matter (DM) in the NMSSM can annihilate into multiple final states to explain the galactic center gamma-ray excess (GCE). In this work we take into account the foreground and background uncertainties for the GCE and investigate these explanations. We carry out a sophisticated scan over the NMSSM parameter space by considering various experimental constraints such as the Higgs data, B-physics observables, DM relic density, LUX experiment and the dSphs constraints. Then for each surviving parameter point we perform a fit to the GCE spectrum by using the correlation matrix that incorporates both the statistical and systematic uncertainties of the measured excess. After examining the properties of the obtained GCE solutions, we conclude that the GCE can be well explained by the pure annihilations and with A (1) being the lighter singlet- dominated CP-odd Higgs boson and H (i) denoting the singlet-dominated CP-even Higgs boson or SM-like Higgs boson, and it can also be explained by the mixed annihilation , A (1) H (1). Among these annihilation channels, can provide the best interpretation with the corresponding p-value reaching 0.55. We also discuss to what extent the future DM direct detection experiments can explore the GCE solutions and conclude that the XENON-1T experiment is very promising in testing nearly all the solutions.
分类： 物理学 >> 基本粒子与场物理学 提交时间： 2016-05-09
摘要： 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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