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PKU HEP Seminar and Workshop (北京大学高能物理组)

A new observable to probe $CP$ violation in $H\gamma\gamma$ coupling

by Dr. Xia Wan (Shaanxi Normal University)

Thursday, November 9, 2017 from to (Asia/Shanghai)
at CHEP ( B105 )
West Building, School of Physics, PKU

The diphoton invariant mass distribution of interference between $gg\to H \to \gamma\gamma$ and $gg\to \gamma\gamma$ at leading order is an almost antisymmetric lineshape around Higgs mass $M_H$. We propose an integral odd around $M_H$ ($\int^{M_H}-\int_{M_H}$) to get the contribution of interference and divide it by the total cross section of Higgs signal, which makes a new observable $A_{int}$. We investigate the $A_{int}$ in Standard Model and various $CP$-violating $H\gamma\gamma$ cases.

It could reach about $10\%$ in SM, and the significance of deviation caused by $CP$ violation could be large as $5\sim10\sigma$, which could constrain the $CP$ violation phase $\xi_\gamma\notin[\pi/2,3\pi/2]$ at $99.9\%$ confidence level.

The $A_{int}$ with both $CP$-violating $H\gamma\gamma$ and $Hgg$ couplings are also studied and the significance is given.

Participants Qing-Hong Cao; Xin Chen; Yandong Liu; Li-Ye Xiao; Ling-Xiao Xu; Rui Zhang; Hao Zhang; Jue Zhang; 世平 和; 晨 申; 浩然 蒋; 安康 魏