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arXiv 1204.6038hep-phhep-ex
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位移超对称

Displaced Supersymmetry

Peter W. Graham, David E. Kaplan, Surjeet Rajendran, Prashant Saraswat

摘要:

在LHC上明显缺乏超伴子的现象,强烈限制了MSSM作为解决层次问题的可行性。这些限制可以通过R-奇偶违反(RPV)来显著缓解。双线性R-宇称破缺,与单个算子L H_u,不需要任何特殊的味道结构,可以自然地嵌入在一个大统一理论,同时避免质子衰变的约束(不像重子数破缺RPV)。在这种情况下,LSP可以自然地长寿命,从而产生位移顶点。许多对撞机的研究,特别是那些选择b喷流或轻子的研究,由于轨道质量和碰撞参量的削减,对具有这种探测器尺度位移衰变的事件不敏感。我们证明,在窗口的衰变长度~1-1000毫米,超伙伴质量的约束可以低至~450 GeV的正方形和~40 GeV的LSP。在参数空间的某些部分,轻LSP可以支配希格斯衰变宽度,从现有的搜索中隐藏希格斯粒子。这个框架激励碰撞器搜索探测器规模的位移顶点。LHCb可能非常适合触发此类事件,而ATLAS和CMS可能需要在事件中丢失能量时触发。

英文摘要:

The apparent absence of light superpartners at the LHC strongly constrains the viability of the MSSM as a solution to the hierarchy problem. These constraints can be significantly alleviated by R-parity violation (RPV). Bilinear R-parity violation, with the single operator L H_u, does not require any special flavor structure and can be naturally embedded in a GUT while avoiding constraints from proton decay (unlike baryon-number-violating RPV). The LSP in this scenario can be naturally long-lived, giving rise to displaced vertices. Many collider searches, particularly those selecting b-jets or leptons, are insensitive to events with such detector-scale displaced decays owing to cuts on track quality and impact parameter. We demonstrate that for decay lengths in the window ~1-1000 mm, constraints on superpartner masses can be as low as ~450 GeV for squarks and ~40 GeV for LSPs. In some parts of parameter space light LSPs can dominate the Higgs decay width, hiding the Higgs from existing searches. This framework motivates collider searches for detector-scale displaced vertices. LHCb may be ideally suited to trigger on such events, while ATLAS and CMS may need to trigger on missing energy in the event.

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