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arXiv 2008.06480hep-phhep-ex
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来自扩展弯曲额外维的KK引力子的LHC信号

LHC Signals for KK Graviton from an Extended Warped Extra Dimension

Kaustubh Agashe, Majid Ekhterachian, Doojin Kim, Deepak Sathyan

摘要:

我们分析了在大型强子对撞机(LHC)上Kaluza-Klein(KK)引力子产生和衰变的信号,在“扩展的”扭曲额外维模型的背景下,标准模型(SM)希格斯和费米子场被限制在通常的紫外/普朗克膜和$\sim O(10)$ TeV之间(新的,“中间”)膜,而SM规范场(和重力)进一步向下传播到$\sim O( \hbox{TeV} )$红外膜。这样的框架抑制了KK粒子效应引起的味道破坏,同时保持了LHC可以获得KK规范玻色子和引力子。我们发现KK引力子的信号与标准翘曲模型中的信号有很大的不同。这是因为KK引力子衰变为顶夸克、希格斯粒子和纵向$W/Z$粒子的主导模式被这两组粒子之间的上述空间分离所抑制,因此允许其他衰变通道自己发光。特别是,我们专注于两个新的衰减通道的KK引力子。第一个是衰变成一对radions,每个radions衰变成一对SM胶子(占主导地位),导致由两对dijet共振组成的共振4喷流终态。另一方面,如果镭子较重和/或KK胶子较轻,则KK引力子大多衰变为KK胶子和SM胶子。由此产生的KK胶子有一个显着的衰变分支部分到radion和SM胶子,从而产生(再次)4喷流签名,但具有不同的底层事件拓扑结构,即,现在有三种不同的共振。我们证明了高亮度LHC(HL-LHC)在两个通道中对(最高)$\sim 4$ TeV的KK引力子都有灵敏度,而在标准的从KK引力子衰变为两个胶子的双喷流共振搜索通道中不太可能有灵敏度.

英文摘要:

We analyze signals at the Large Hadron Collider (LHC) from production and decay of Kaluza-Klein (KK) gravitons in the context of "extended" warped extra-dimensional models, where the standard model (SM) Higgs and fermion fields are restricted to be in-between the usual ultraviolet/Planck brane and a $\sim O(10)$ TeV (new, "intermediate") brane, whereas the SM gauge fields (and gravity) propagate further down to the $\sim O( \hbox{TeV} )$ infrared brane. Such a framework suppresses flavor violation stemming from KK particle effects, while keeping the KK gauge bosons and gravitons accessible to the LHC. We find that the signals from KK graviton are significantly different than in the standard warped model. This is because the usually dominant decay modes of KK gravitons into top quark, Higgs and longitudinal $W/Z$ particles are suppressed by the above spatial separation between these two sets of particles, thus other decay channels are allowed to shine themselves. In particular, we focus on two novel decay channels of the KK graviton. The first one is the decay into a pair of radions, each of which decays (dominantly) into a pair of SM gluons, resulting in a resonant 4-jet final state consisting of two pairs of dijet resonance. On the other hand, if the radion is heavier and/or KK gluon is lighter, then the KK graviton mostly decays into a KK gluon and a SM gluon. The resulting KK gluon has a significant decay branching fraction into radion and SM gluon, thereby generating (again) a 4-jet signature, but with a different underlying event topology, i.e., featuring now three different resonances. We demonstrate that the High-Luminosity LHC (HL-LHC) has sensitivity to KK graviton of (up to) $\sim 4$ TeV in both channels, whereas it is unlikely to have sensitivity in the standard dijet resonance search channel from KK graviton decay into two gluons.

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