The ATLAS experiment has recently presented its search results for final states containing jets and/or b-jet(s) and missing transverse momentum, corresponding to an integrated luminosity of 165 pb^{-1}. We employ this data to constrain a class of supersymmetric SU(4)_c X SU(2)_L X SU(2)_R models with t-b-τYukawa unification, in which the gluino is the next to lightest supersymmetric particle (NLSP). The NLSP gluino is slightly (~10-30%) heavier than the the LSP dark matter neutralino, and it primarily decays into the latter and a quark-antiquark pair or gluon. We find that NLSP gluino masses below ~300 GeV are excluded by the ATLAS data. For LSP neutralino mass ~200-300 GeV and μ>0, where μis the coefficient of the MSSM Higgs bilinear term, the LHC constraints in some cases on the spin-dependent (spin-independent) neutralino-nucleon cross section are significantly more stringent than the expected bounds from IceCube DeepCore (Xenon 1T/SuperCDMS). For μ<0, this also holds for the spin-dependent cross sections.
我们研究了在Tevatron和7 TeV LHC上发生的胶子-双星共湮灭的对撞机现象。例如,这种情况可以在一类具有非普适的高吉诺质量和t-b-τ汤川统一的现实超对称模型中实现。NLSP的胶子和LSP的比诺应该是近简并的质量,使典型的胶子搜索通道涉及轻子或硬喷流是不可用的。因此,胶子可以比直接搜索得到的各种质量界限更轻。我们提出了一个新的搜索NLSP胶子的方法,该方法涉及三体衰变\tilde{g} -> b \bar{b} \tilde χ_1^0的多b末态.我们确定了两个真实的模型,其质量约为300 GeV的三体衰变是占主导地位的,并表明,在积分亮度为10 fb^{-1}的Tevatron上可以实现4.5 σ的观测灵敏度。对于积分亮度为50 pb^{-1}的7 TeV LHC,两个模型的信号事件数为O(10),与可忽略的SM背景事件相比。
Closing in on compressed gluino-neutralino spectra at the LHC
在最小超对称标准模型(MSSM)的背景下,一个巨大的参数空间在LHC运行I之后被统治。在$m_{\tilde{g}}-\m_{\tildeχ_{1}^{0}}$平面上的各种排斥轮廓是由实验合作推导出来的,所有这些都是基于三体胶子衰变拓扑结构。然而,这些限制与模型密切相关,并不总是反映排除水平。如果胶子-中性伴子光谱被压缩,那么目前的质量极限可以大大降低。在这种情况下,胶子$\gino \ra g \neut{1}$的辐射衰变可以占主导地位,并被用作小质量分裂的灵敏探针。我们研究的敏感性约束的一些运行I实验搜索后,在\texttt{MadAnalysis5}框架内重铸这种衰减。重新铸造的搜索现在是\texttt{MadAnalysis5}公共分析数据库的一部分。我们还设计了一个专门的搜索策略,并探讨其前景,以揭示这种衰变模式的胶子在运行II的大型强子对撞机。我们强调,多喷流搜索策略可能比单喷流搜索策略更敏感,即使在质量差异非常小的情况下。
We explore the implications of resolving the muon g-2 anomaly in a SU(4)_c x SU(2)_L x SU(2)_R model, where the soft supersymmetry breaking scalar and gaugino masses break the left-right (LR) symmetry. A 2 sigma resolution of the anomaly requires relatively light sleptons, chargino and LSP neutralino. The stau turns out to be the NLSP of mass <~ 400 GeV, and the sleptons from the first two families can be as heavy as about 800 GeV. The chargino is also required to be lighter than about 600 GeV to accommodate the muon g-2 solutions consistent with the dark matter relic density constraint. The d…
We explore the implications of third family ($t-b-τ$) quasi-Yukawa unification (QYU) for collider and dark matter (DM) searches within the framework of a supersymmetric $SU(4)_c \times SU(2)_L \times SU(2)_R$ model. The deviation from exact Yukawa unification is quantified through the relation $y_t : y_b : y_τ= |1+C|:|1-C|:|1+3C|$, with $C$ being a real parameter ($|C| \leq 0.2$). We allow for the breaking of left-right symmetry both by the soft scalar and gaugino mass parameters and obtain a variety of viable solutions that predict the sparticle mass spectrum including LSP DM (whose stability…
In this paper we explore the possibility of explaining the muon $g-2$ anomaly in various types of supersymmetric extensions of the Standard Model. In particular, we investigate and compare the phenomenological constraints in the MSSM with stable neutralino and the other types of scenarios where the neutralino is unstable. For the latter case we study the Gauge Mediated SUSY Breaking (GMSB) scenario with very light gravitino and the $UDD$-type R-Parity Violating (RPV) scenario. In the MSSM with stable neutralino, the parameter region favoured by the $(g-2)_μ$ is strongly constrained by the neut…
We employ the ATLAS search results for events containing jets and large missing transverse momentum, corresponding to an integrated luminosity of 1 fb^{-1}, to investigate the constrained minimal supersymmetric model (CMSSM) with b-τYukawa coupling unification. In this scenario, one of the stops is the next-to-lightest supersymmetric particle (NLSP), which co-annihilates with the lightest (LSP) neutralino to yield the desired dark matter relic abundance. The NLSP stop, here taken to be lighter than the top quark, is slightly (<~ 20%-30%) heavier than the LSP neutralino, and it primarily decays…
ATLAS on-Z Excess via gluino-Higgsino-singlino decay chains in the NMSSM
最近,ATLAS实验报道了在寻找超对称粒子时,在Z上信号区域中有3.0 σ过量。我们发现次极小超对称标准模型可以通过产生主要通过$\tilde{g} \to g \tildeχ^0_{2,3} \to g Z \tildeχ^0_{1}$衰变的胶子来解释这种过剩,其中$\tildeχ^0_{2,3}$和$\tildeχ^0_1$分别是Higgsino和类单中微子.同时,我们还证明了所观测到的暗物质密度可以用类单中微子的热遗迹密度来解释。我们还讨论了在大型强子对撞机上寻找这种情况下的希格斯扇区。
Impact of squark generation mixing on the search for squarks and gluinos at LHC
在最小超对称标准模型(MSSM)下,研究了LHC中夸克生成混合对夸克和胶子产生和衰变的影响。我们发现,混合效应可以是非常大的平方代混合参数的一个显着范围内,尽管非常强的约束夸克味违反(QFV)从B介子的实验数据。我们发现在有利的条件下,QFV衰变分支比B(Gluino -> c bar{t}(t bar{c})neutralino_1)可以高达50%,这可能导致在LHC上产生显著的QFV信号。我们还发现夸克生成混合可以在粲顶夸克不变质量分布中产生一种新的多边(3边或4边)结构。此外,我们还发现由于混合效应,两个最轻的上型方核~ u_{1,2}可以同时对衰变~u_i -> c neutralino_1和~u_i -> t neutralino_1产生很大的分支比,从而在LHC上以显著的速率产生QFV信号“pp -> c bar{t}(t bar{c})+ missing-E_T + X”.这些显着的签名可以提供一个强有力的测试超对称QFV在LHC和可能有重要的影响,寻找方和胶子和MSSM参数的确定在LHC。
Impact of squark generation mixing on the search for gluinos at LHC
在最小超对称标准模型(MSSM)中,研究了平方生成混合对胶子衰变的影响。我们发现,尽管B介子观测量对夸克味破坏(QFV)的实验约束很强,但由于这种效应,在MSSM参数空间的相当一部分,QFV的胶子衰变分支比B(胶子-> c bar{t}(t bar{c})+中性子1)可以很大(高达~50%).这可能对寻找胶子和在LHC上确定MSSM参数产生重要影响。
Many faces of low mass neutralino dark matter in the unconstrained MSSM, LHC data and new signals
如果所有强相互作用超粒子(方子和胶子)在一个无约束的最小超对称标准模型(MSSM)的重量比相应的质量下限的最小超引力(mSUGRA)模型,获得当前的LHC实验,然后现有的数据允许各种电弱(EW)部门与轻超粒子产生暗物质(DM)的残骸密度所允许的WMAP数据。一些超微粒子可能刚好位于LEP的现有下限之上,并导致许多在mSUGRA中不常见的新DM产生机制。这是通过重新访问ATLAS合作获得的上述方胶子质量极限,与不受约束的EW部门与质量不相关的强部门。使用他们的选择标准和相应的截面限制,我们发现在发电机水平使用Pythia,在大多数情况下,质量限制的变化,如果有的话,最多10-12%。然而,在某些情况下,胶子质量极限的弛豫更大($\approx 20%$)。如果在无约束MSSM中的强相互作用超粒子的子集在LHC的范围内,则可以获得对EW扇区敏感的信号。这是通过模拟$blj$ $\etslash$,$l= e and μ$,和$bτj$ $\etslash$信号在i)光停止的情况下,和ii)光停止胶子的情况下,与各种轻EW部门所允许的WMAP数据。一些更一般的模型可以用非普适的标量和高吉诺质量来实现。