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arXiv 1601.07396hep-phhep-ex
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类矢量粒子模型中750 GeV和LHC约束下的双光子过剩

Diphoton excess at 750 GeV and LHC constraints in models with vector-like particles

Junichiro Kawamura, Yuji Omura

备注：
19 pages, 6 figures, 6 tables; added references
发表信息：
Phys. Rev. D 93, 115011 (2016)
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摘要：

最近，ATLAS和CMS合作报告了双光子通道中$750$ GeV附近的过量。这可能是揭示标准模型之外的新物理学的证据。在本文中，我们考虑模型与$750$ GeV标量和矢量类粒子，通过汤川耦合相互耦合。标量的双光子衰变被涉及额外的有色粒子的回路图增强。我们调查不仅设置所需的过剩，但也LHC的约束，特别是有关的矢量粒子。我们考虑的情况下，额外的颜色粒子衰变到夸克和暗物质（DM）通过汤川耦合。然后，来自矢量状粒子的信号是具有大的缺失能量的双射、$b\overline{b}$和/或$t\overline{t}$。我们讨论了两种可能的设置：一个是一个模型与矢量类费米子和标量DM，另一个是一个模型与矢量类标量和费米子DM。我们建议在每一种情况下的参数区域的优势，并研究的限制基于最新的LHC结果在$\sqrt{s}=8$ TeV和$13$ TeV。我们的结论是，有利的区域几乎被排除在LHC的界限，特别是当$750$ GeV标量占主导地位的衰变到DM。如果额外的色粒子只衰变为顶（底）夸克和DM，则类矢量粒子和DM的质量差应小于${\cal O}(100)$ GeV（${\cal O}(10)$ GeV），以实现大的双光子信号和大的衰变宽度。否则，这些情况已经被最新的LHC结果排除在外。

英文摘要：

Recently, the ATLAS and CMS collaborations report excesses around $750$ GeV in the diphoton channels. This might be the evidence which reveals new physics beyond the Standard Model. In this paper, we consider models with a $750$ GeV scalar and vector-like particles, which couple each other through Yukawa couplings. The diphoton decay of the scalar is enhanced by the loop diagrams involving the extra colored particles. We investigate not only the setup required by the excesses, but also the LHC constraints, especially concerned with the vector-like particles. We consider the scenario that the extra colored particles decay to quarks and a dark matter (DM) via Yukawa couplings. Then, the signals from the vector-like particles are dijet, $b\overline{b}$ and/or $t\overline{t}$ with large missing energy. We discuss two possibilities for the setups: One is a model with vector-like fermions and a scalar DM, and the other is a model with vector-like scalars and a fermionic DM. We suggest the parameter region favored by the excess in the each case, and study the constraints based on the latest LHC results at $\sqrt{s}=8$ TeV and $13$ TeV. We conclude that the favored region is almost excluded by the LHC bounds, especially when the $750$ GeV scalar dominantly decays to DMs. The mass differences between the vector-like particles and the DM should be less than ${\cal O}(100)$ GeV (${\cal O}(10)$ GeV) to realize the large diphoton signal and the large decay width, if the extra colored particle only decays to a top (bottom) quark and a DM. Otherwise, these scenarios are already excluded by the latest LHC results.

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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