Speaker
Description
We consider $Z'$ models that can generate the two `1D’ new physics scenarios with Wilson coefficients $C_9^{\rm NP} <0$ and $C_9^{\rm NP} = -C_{10}^{\rm NP}$, to account for the anomalies in $b \to s \ell \ell$ decays. We present the $1\sigma$ favored parameter space of these two classes of models using updated constraints from $CP$-conserving and $CP$-violating observables, $B_s$-mixing and neutrino trident. We show that the predictions of direct $CP$ asymmetry $A_{CP}$ in $B \to K^+ \mu \mu$ decays close to the $c\bar{c}$ resonance region can be used to detect the presence of new $CP$ violating phases in the couplings. The preferred parameter space of $Z'$ models generating scenario $C_9^{\rm NP} <0$ allows for an enhancement in the integrated $A_{CP}$ in $q^2 = [8,9]\mathrm{GeV}^2$ and $q^2 = [6,7]\mathrm{GeV}^2$ up to $\pm 10\%$ and $\pm 5\%$ respectively. While such an enhancement is possible in $Z'$ models generating the scenario $C_9^{\rm NP} = -C_{10}^{\rm NP}$, the favored parameter space prefers only positive values. Hence, a future more precise measurement of $A_{CP}$ near the $c\bar{c}$ resonance can help in distinguishing between the two classes of $Z'$ models.
| Session | Quark and Lepton Flavour Physics |
|---|
