Abstract
Confining hidden sectors at the GeV scale are well motivated by asymmetric dark matter and naturalness considerations and can also give interesting collider signatures. Here we study such sectors connected to the Standard Model by a TeV scale mediator charged under both QCD and the dark force. Such a mediator admits a Yukawa coupling between quarks and dark quarks which is generically flavour and CP violating. We show that in contrast to expectation, electric dipole moments do not place a strong constraint on this scenario even with O(1) CP-violating phases. We also quantitatively explore constraints from ∆F = 1, 2 processes as a function of the number of dark quark flavours. Finally, we describe the reach of upcoming measurements at Belle-II and KOTO, and we propose new CP-odd observables in rare meson decays that may be sensitive to the CP-violating nature of the dark sector.
Highlights
The nature of dark matter is one of the most important open questions in fundamental physics
In this work we focus on the constraints that arise from Yukawa couplings of the X scalar in the Bai and Schwaller [16] (BS) model
Dark QCD models that confine at the GeV scale with a TeV scale mediator charged under both QCD and dark QCD are a well motivated paradigm for asymmetric dark matter [16]
Summary
The nature of dark matter is one of the most important open questions in fundamental physics. The mass of the proton is controlled by the confinement scale of QCD This suggests that the asymmetric dark matter should be a bound state of a new dark strong force. This was realized concretely in the model of Bai and Schwaller [16] (BS) which has an SU(Nc) dark force whose running gauge coupling is related to that of QCD and naturally predicts a dark confinement scale at around a GeV. In this work we focus on the constraints that arise from Yukawa couplings of the X scalar in the BS model The couplings of this mediator to SM quarks breaks some of the SM accidental flavour symmetries and generically gives rise to flavour and CP violating processes. In the appendices we give a brief review of the flavour and CP observables used in this work, and give various technical details on how we compute bounds
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