Speaker
Description
Electric dipole moments (EDMs) provide strong bounds on the CP structure of many New Physics (NP) scenarios. In this work, we study the charm Chromo-EDM (CEDM) within a new light scalar singlet with top-quark Flavour-Changing Neutral Current (FCNC) interactions. Such scalar singlet appears naturally in many well-motivated NP scenarios, such as the composite Higgs models. Unlike the Higgs boson in the Standard Model, it can induce large FCNCs in the top sector. Besides the CEDM, we also include the low-energy constraints from the $B_s \to \mu^+ \mu^-$ decay and the muon anomalous magnetic moment $(g-2)_\mu$. We also perform a detailed Monte-Carlo simulation of the channel $pp \to t S +j$ with $S \to \mu^+ \mu^-$ and $S \to b \bar b$, and investigate the LHC sensitivity to the $tcS$ couplings. For the CP-violating $tcS$ couplings $y_{R,L}^{ct}=|y_{R,L}^{ct}|e^{i\theta_{R,L}}$, it is found that the CEDM can provide bounds on the phase difference $\theta_L-\theta_R$, while the CP observables $\mathcal{A}_{\Delta\Gamma_s}^{\mu\mu}$ and $\mathcal{S}_{\mu\mu}$ of the $B_s \to \mu^+ \mu^-$ decay are sensitive to the phase $\theta_R$. Therefore, they are complementary to each other in probing the CP phases of the $tcS$ couplings.
