arXiv 0802.00222008-02hep-ph

隐藏的量子点：在强子对撞机上重建新物理质量的技术

Hidden Thresholds: A Technique for Reconstructing New Physics Masses at Hadron Colliders

P. Huang, N. Kersting, H. H. Yang

备注：: 15 pages, 6 figures; Discussion simplified

摘要：

提出了一种改进的从不变质量端点重构新物理质量的方法。传统的方法只关注单个NP粒子的衰变，而我们的方法考虑了两个或多个NP粒子（$ABC...$）在一个更大的衰变链中的衰变：$ anything \to ABC... \to ... \to jets + leptons$。尽管在强子对撞机中，“任何东西”的质心能量$E_{CM}$的变化都是不可预测的，但许多事件的样本仍然表达了阈值产生$E_{CM} = m_A + m_B + ...$的特征：由最终喷流和轻子动量构建的不变质量以一种方式相关，使得它们的阈值端点在散点图中非常明显。我们说明了这种技术的生产中的MSSM：$anything \to \widetildeχ_{i}^0 \widetildeχ_{j}^0$（$i,j=2,3,4$），随后通过上或离壳层的轻子衰变到四个轻子的两个中性伴子。假设相关的超对称谱低于$1 TeV$，并且方子/胶子最终衰变为中性伴子，我们的MC研究表明，在LHC（$10-30 fb^{-1}$）的一个低光度年可以定量地确定在壳层与离壳层衰变，并发现相关的中性伴子和slepton质量小于10%。

英文摘要：

We present an improved method of reconstructing New Physics (NP) masses from invariant mass endpoints. While the traditional method focuses on a single NP decay, our method considers the decays of two or more NP particles ($ABC...$) in a grander decay chain: $ anything \to ABC... \to ... \to jets + leptons$. Though the center-of-mass energy $E_{CM}$ of `anything' varies unpredictably at a hadron collider, a sample of many events nonetheless expresses features of threshold production $E_{CM} = m_A + m_B + ...$: invariant masses constructed from the final jet and lepton momenta are correlated in a way that makes their threshold endpoints visually obvious in a scatterplot. We illustrate this technique for the production of two neutralinos in the MSSM: $anything \to \widetildeχ_{i}^0 \widetildeχ_{j}^0$ ($i,j=2,3,4$) which subsequently decay via on- or off-shell sleptons to four leptons. Assuming the relevant SUSY spectrum is below $1 TeV$ and squarks/gluinos eventually decay to neutralinos, our MC study shows that one low-luminosity year at the LHC ($10-30 fb^{-1}$) can quantitatively determine on- versus off-shell decays and find the relevant neutralino and slepton masses to less than 10 percent.

机构、总结、中文摘要均由AI分析而来，可能存在错误，请以论文正文为准。

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英文摘要：

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