New physics in b→sμ+μ−: Distinguishing models through CP-violating effects

• Published in: Physical review. D 2017-07, Vol.96 (1)
• Main Authors: Alok, Ashutosh Kumar, Bhattacharya, Bhubanjyoti, Kumar, Dinesh, Kumar, Jacky, London, David, Sankar, S Uma
• Format: Article
• Language: English
• Subjects: Astronomy & Astrophysics; Asymmetry; Coupling; CP violation; Physics
• ISSN: 2470-0010; 2470-0029
• DOI: 10.1103/PhysRevD.96.015034

At present, there are several measurements of B decays that exhibit discrepancies with the predictions of the SM, and suggest the presence of new physics (NP) in b→sμ+μ− transitions. Many NP models have been proposed as explanations. These involve the tree-level exchange of a leptoquark (LQ) or a flavor-changing Z′ boson. In this paper we examine whether it is possible to distinguish the various models via CP-violating effects in B→K(*)μ+μ−. Using fits to the data, we find the following results. Of all possible LQ models, only three can explain the data, and these are all equivalent as far as b→sμ+μ− processes are concerned. In this single LQ model, the weak phase of the coupling can be large, leading to some sizable CP asymmetries in B→K(*)μ+μ−. There is a spectrum of Z′ models; the key parameter is gLμμ, which describes the strength of the Z′ coupling to μ+μ−. If gLμμ is small (large), the constraints from Bs0−B¯s0 mixing are stringent (weak), leading to a small (large) value of the NP weak phase, and corresponding small (large) CP asymmetries. We therefore find that the measurement of CP-violating asymmetries in B→K(*)μ+μ− can indeed distinguish among NP b→sμ+μ− models.