Reconciling anomalous measurements in $B_s-{\bar{B}}_s$ mixing: the role of CPT-conserving and CPT-violating new physics

Abstract

Recently observed anomalies in the $B_s\to J/\psi \varphi$ decay and the like-sign dimuon asymmetry $A_{sl}^b$ hint at possible new physics (NP) in the $\text{bsbsbar}$ mixing. We parameterize the NP with four model-independent quantities: the magnitudes and phases of the dispersive part $M_{12}$ and the absorptive part ${\Gamma }_{12}$ of the NP contribution to the effective Hamiltonian. We constrain these parameters using the four observables $\Delta M_s$, $\Delta {\Gamma }_s$, the mixing phase ${\beta }_s^{J/\psi \varphi }$, and $A_{sl}^b$. Our quantitative fit indicates that the NP should contribute a significant dispersive as well as absorptive part. In fact, models that do not contribute a new absorptive part are disfavored at more than 99% confidence level. We extend this formalism to include CPT violation, and show that CPT violation by itself, or even in presence of CPT-conserving new physics without an absorptive part, helps only marginally in the simultaneous resolution of these anomalies. The NP absorptive contribution to $\text{bsbsbar}$ mixing therefore seems to be essential, and would imply a large branching fraction for channels like $B_s\to {\tau }^{+}{\tau }^{-}$.

Comments: The final version to be published in PRD. Earlier results updated (strengthened) with 9.1 fb^{-1} data from D0