Semileptonic B and B_s decays involving scalar and axial-vector mesons

Xian-Wei Kang,Ling-Yun Dai,Tao Luo,Chao Wang,Yi Zhang

doi:10.1140/epjc/s10052-018-6385-9

Abstract

We report our theoretical calculations on the branching fractions for the semileptonic B and B_s decays based on the form factors in the covariant light-front quark model. That is, B (B_s) rightarrow (P,, V,, S,,A) ell nu _ell , where P and V denote the pseudoscalar and vector mesons, respectively, while S denotes the scalar meson with mass above 1 GeV and A the axial-vector meson. The branching fractions for the semileptonic Brightarrow P and V modes have been measured very well in experiment and our theoretical values are in good agreement with them. The ones for Brightarrow S and A modes are our theoretical predictions. There is little experimental information on the semileptonic B_s decays although much theoretical effort has been done. In addition, we predict the branching fractions of Brightarrow D^*_0(2400) ell bar{nu }_ell and B_srightarrow D^{*-}_{s0}(2317) ell bar{nu }_ell as (2.31pm 0.25)times 10^{-3} and (3.07pm 0.34)times 10^{-3}, in order, assuming them as the conventional mesons with quark-antiquark configuration. The high luminosity e^+e^- collider SuperKEKB/Belle-II is running, with the data sample enhanced by a factor of 40 compared to Belle, which will provide huge opportunity for the test of the theoretical predictions and further help understand the inner structure of these scalar and axial-vector mesons, e.g., the glueball content of f_0(1710) and the mixing angles for the axial-vector mesons. These decay channels can also be accessed by the LHCb experiment.

Highlights

The CP violation is one of the necessary Sakharov conditions for the emergence of matter-antimatter asymmetry [1,2,3], which is a key question in the nature
The Cabibbo– Kobayashi–Maskawa (CKM) matrix [4,5] has been an indispensable skeleton of the Standard Model (SM), which successfully describes the CP violation in the quark sector
In the CKM matrix, the unitarity relation |Vub|2 +|Vcb|2 +|Vtb|2 = 1 is fulfilled, and any deviation of this unitarity constraint will be a signal of New Physics

Summary

Introduction

The CP violation is one of the necessary Sakharov conditions for the emergence of matter-antimatter asymmetry [1,2,3], which is a key question in the nature. We will consider B(Bs) → (P, V, S, A) ν decay, where P and V denote the pseudoscalar and vector mesons, respectively, while S denotes the scalar meson with mass above 1 GeV and A the axial vector meson In these processes, either |Vub| or |Vcb| is involved. There is a mismatch for the extraction of |Vub| from the inclusive and exclusive decays, which is the so-called |Vub| puzzle [6,19] The measurement of these channels can certainly help for rendering more information on the determination of CKM matrix elements, at least as a. From the experimental point of view, Belle has accumulated huge data samples, that can be exploited to measure the branching fractions and hadronic transition form factors for the various semileptonic decay channels, in order to test or constrain the various theoretical models. Our predicted branching fractions are typically in the order of 10−5 so that they can be, in principle, accessed by the Belle/Belle-II and LHCb experiments

Theoretical framework

Conclusion