Angular analysis of B¯→D2*(→Dπ)ℓν¯ decay and new physics

Rusa Mandal

doi:10.1103/physrevd.101.033007

Rusa Mandal

Open Access

https://doi.org/10.1103/physrevd.101.033007

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Abstract

We derive the four-fold angular distribution for the semileptonic decay $\bar{B}\to D_2^*(\to D \pi)\,\ell \bar{\nu}$ where $D_2^*$(2460) is a tensor meson. We start with the most general beyond the Standard Model (SM) dimension-six effective Hamiltonian which comprises (axial)vector, (pseudo)scalar and tensor operators for both quark and lepton currents, and it also includes the right-handed neutrinos. The decay can be described by 16 transversity amplitudes and it provides a multitude of observables which can be extracted from data. We investigate the observables in the context of the SM and the new physics scenarios which can explain the intriguing discrepancies observed in the $b \to c \tau \bar{\nu}$ data.

Highlights

In the absence of any clean signal of beyond the Standard Model (SM) particle, the effective theory analysis has become one of the primary directions to pursue
In a situation where the scale of new physics (NP) might be quite higher and the direct production remains awaiting at the colliders, higher dimensional operators can capture its effect
We have explored the semileptonic decay B → DÃ2ð→ DπÞlν, where DÃ2 is a tensor meson with a mass and decay width of 2460 MeV and ∼48 MeV, respectively

Summary

INTRODUCTION

In the absence of any clean signal of beyond the Standard Model (SM) particle, the effective theory analysis has become one of the primary directions to pursue. In the case for the ratio RJ=ψ , which has the same quark-level transition b → clν, in the Bc meson system, the LHCb Collaboration has observed the hint of another discrepancy [10] within a 2σ level. While these hints are subject to confirmation or falsification with more statistics, efforts to explore additional modes mediated by the same parton-level transition should be open ended. The full angular distribution provides additional information about the orientations of the final states and the polarizations of the DÃ2 meson through a multitude of observables.

THEORETICAL FRAMEWORK

ANGULAR DISTRIBUTION AND OBSERVABLES

MODEL INDEPENDENT PHENOMENOLOGY WITH NEW PHYSICS

SUMMARY AND DISCUSSION