Tau polarization measurements at the LHC in supersymmetric models with a long-lived stau
Tau polarization measurements at the LHC in supersymmetric models with a long-lived stau
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DOI：
10.1103/physrevd.82.035007
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发表时间：
2010-06
影响因子：
5
通讯作者：
R. Kitano;Mitsutoshi Nakamura
中科院分区：
文献类型：
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作者：
R. Kitano;Mitsutoshi Nakamura
在大型强子对撞机实验中，具有长寿命STAU的超对称性(SUSY)是一个吸引人的场景，因为人们可以在每个SUSY事件中直接观察到STU轨迹，从而有可能精确地测量SUSY粒子的质量。在这个场景中，我们讨论了观察/测量超对称粒子之间相互作用中宇称破坏的可能性。这样的测量对于确定超对称粒子的自旋和手性将是很重要的。我们使用级联衰减链的最后一步：${\ensuremath{\chi}}^{0}\ensuremath{\rightarrow}\stackrel{\texttildelow{}}{\ensuremath{\tau}}\ensuremath{\tau}\ensuremath{\rightarrow}\stackrel{\texttildelow{}}{\ensuremath{\tau}}(l\ensuremath{\nu}\overline{\ensuremath{\nu}})$，，其中，通过观察末态轻子的能量分布，可以统计地确定tau轻子的极化。与中性微子微分衰变宽度的理论公式相比，可以提取Stau、tau轻子和中性微子相互作用顶点中宇称破缺的大小。我们进行了蒙特卡罗模拟，看看这种影响在大型强子对撞机实验中是否可见。
Supersymmetry (SUSY) with a long-lived stau is an attractive scenario in the LHC experiments because one can directly observe stau tracks in each SUSY event, and thus precise measurements of SUSY particle masses are possible. In this scenario, we discuss the possibility to observe/measure parity violation in interactions among SUSY particles. Such a measurement will be important in determining the spins and chiralities of SUSY particles. We use the last step of the cascade-decay chain: ${\ensuremath{\chi}}^{0}\ensuremath{\rightarrow}\stackrel{\texttildelow{}}{\ensuremath{\tau}}\ensuremath{\tau}\ensuremath{\rightarrow}\stackrel{\texttildelow{}}{\ensuremath{\tau}}(l\ensuremath{\nu}\overline{\ensuremath{\nu}})$, where the polarization of the tau lepton can be determined statistically by looking at the energy distribution of the final state lepton. Comparing with the theoretical formula of the neutralino differential decay width, one can extract the size of parity violation in the interaction vertices among the stau, the tau lepton, and the neutralino. We perform a Monte Carlo simulation to see if the effect is visible at the LHC experiments.