摘要
Dark sector may couple to the Standard Model via one or more mediator particles.We discuss two types of mediators:the dark photon A’ and the dark scalar mediator Φ .The total cross-sections and various differential distributions of the processes e+e-→qqA’ and e+e→qqφ（q=u,d,c,s and b quarks） are discussed.We focus on the study of the invisible due to the cleaner background at future e+e-colliders.It is found that the kinematic distributions of the two-jet system could be used to identify（or exclude） the dark photon and the dark scalar mediator,as well as to distinguish between them.We further study the possibility of a search for dark photons at a future CEPC experiment with s1/2=91.2 GeV and 240 GeV.With CEPC running at s1/2=91.2 GeV,it would be possible to perform a decisive measurement of the dark photon（20 GeV <mA’ <60 GeV） in less than one operating year.The lower limits of the integrated luminosity for the significance S/B1/2=2σ,3σ and 5σ are presented.
Dark sector may couple to the Standard Model via one or more mediator particles.We discuss two types of mediators:the dark photon A’and the dark scalar mediatorΦ.The total cross-sections and various differential distributions of the processes e+e-→qqA’and e+e→qqφ(q=u,d,c,s and b quarks)are discussed.We focus on the study of the invisible due to the cleaner background at future e+e-colliders.It is found that the kinematic distributions of the two-jet system could be used to identify(or exclude)the dark photon and the dark scalar mediator,as well as to distinguish between them.We further study the possibility of a search for dark photons at a future CEPC experiment with s1/2=91.2 GeV and 240 GeV.With CEPC running at s1/2=91.2 GeV,it would be possible to perform a decisive measurement of the dark photon(20 GeV<mN<60 GeV)in less than one operating year.The lower limits of the integrated luminosity for the significance S/√B=2σ,3σand 5σare presented.
基金
supported in part by the National Natural Science Foundation of China(11875179,11325525,11635009,11775130,11905112)
the Natural Science Foundation of Shandong Province(ZR2017MA002,ZR2019QA012)
the Fundamental Research Funds of Shandong University(2019GN038)
