Probing dark matter particles at CEPC

Abstract

We investigate the capability of the future electron collider CEPC in probing the parameter space of several dark matter models, including millicharged dark matter models, Z portal dark matter models, and effective field theory dark matter models. In our analysis, the monophoton final state is used as the primary channel to detect dark matter models at CEPC. To maximize the signal to background significance, we study the energy and angular distributions of the monophoton channel arising from dark matter models and from the standard model to design a set of detector cuts. For the Z portal dark matter, we also analyze the Z boson visible decay channel which is found to be complementary to the monophoton channel in certain parameter space. The CEPC reach in the parameter space of dark matter models is also put in comparison with Xenon1T. We find that CEPC has the unprecedented sensitivity to certain parameter space for the dark matter models considered; for example, CEPC can improve the limits on millicharge by one order of magnitude than previous collider experiments for O(1) − 100 GeV dark matter.

Constraining nonstandard neutrino interactions at electron colliders

“…2 For the monophoton signature at CEPC, we use the cuts for the final detected photon (hereafter the "basic cuts") following the CEPC CDR [49]: |z γ | < 0.99 and E γ > 0.1 GeV. Similar as the symmetric STCF, we also apply the cuts (28) as "advanced cuts" with cos θ b = 0.99 to remove the reducible background events [57].…”

Probing sub-GeV leptophilic dark matter at Belle II and NA64

“…where Z denotes the light mediator, χ is the dark matter, l is the SM charged lepton, g χ,l v (g χ,l a ) is the vector (axialvector) coupling. The mono-photon cross section at the electron colliders for the process e + e − → γZ → γχ χ is given by [47]…”

Millicharged particles at electron colliders

“…where θ b is the polar angle corresponding to the edge of the detector [16]. For the Belle II detector, which is asymmetric, E m γ in the c.m.…”

“…Previous particle accelerator constraints on MCPs include colliders [8][9][10], SLAC electron beam dump experiment [11], and E613 [12,13]. Recently, sensitivity of probing MCPs has also been studied in various accelerator experiments, including BESIII [14], LHC [15], Circular Electron Positron Collider (CEPC) [16], NA64 [17,18], and Light Dark Matter eXperiment (LDMX) [19]. Astrophysical constraints include white dwarf [8,9,20], supernova [9,21,22], cosmic microwave background (CMB) [23,24], big bang nucleosynthesis [8,9,[25][26][27], red giants [8,20,25,26], and the Sun [27].…”