# The Fifth Annual Large Hadron Collider Physics conference (LHCP2017)

May 15 – 20, 2017
Shanghai Jiao Tong University
Asia/Shanghai timezone
Please bring you passport details to the registration desk to confirm your participation for the excursions

## Dark Photon Search at A Circular e+e− Collider

May 16, 2017, 2:00 PM
2h
Haoran 102 (Shanghai Jiao Tong University)

Xuhui Campus

### Speaker

Min He (INPAC, Deparment of Physics and Astronomy, Shanghai Jiao Tong University)

### Description

One of the interesting portals linking a dark sector and the standard model (SM) is the kinetic mixing between the SM $U(1)_Y$ field with a new dark photon $A'$ from a $U(1)_{A'}$ gauge interaction. Stringent limits have been obtained for the kinetic mixing parameter $\epsilon$ through various processes. In this work, we study the possibility of searching for a dark photon interaction at a circular $e^+e^-$ collider through the process $e^+ e^-\to \gamma A^{\prime *} \to \gamma \mu^+\mu^-$. We find that the constraint on $\epsilon^2$ for dark photon mass in the few tens of GeV range, assuming that the $\mu^+\mu^-$ invariant mass can be measured to an accuracy of $0.5\%m_{A'}$, can be better than $3\times 10^{-6}$ for the proposed CEPC with a ten-year running at 3$\sigma$ (statistic) level, and better than $2\times 10^{-6}$ for FCC-ee with even just one-year running at $\sqrt{s} = 240$ GeV, better than the LHC and other facilities can do in a similar dark photon mass range. For FCC-ee, running at $\sqrt{s}=160$ GeV, the constraint can be even better.

### Primary authors

Min He (INPAC, Deparment of Physics and Astronomy, Shanghai Jiao Tong University) Xiao-Gang He Mr Cheng-Kai Huang