Exploring new physics in the FCNC $B_c \to D_s \nu \bar{\nu}$ channel

TL;DR

This paper investigates the rare decay $B_c o D_s uar{ u}$ via the $b o s uar{ u}$ transition, exploring potential new physics effects within an effective Hamiltonian and leptoquark models, using lattice QCD form factors.

Contribution

It provides the first detailed analysis of the $B_c o D_s uar{ u}$ decay channel including new physics scenarios and lattice QCD inputs.

Findings

Predicted branching fractions within the standard model.

Predicted branching fractions with new physics contributions.

Constraints on new physics from decay predictions.

Abstract

The rare $b \to s \ell^+\ell^-$ transition is a well-explored transition, particularly for new physics beyond the standard model. Similar to this transition, another flavor changing neutral current transition $b \to s \nu\bar{\nu}$ involving a dineutrino pair also plays an important role in the search for new physics. The $B \to K \nu\bar{\nu}$ mode is one such dineutrino channel that has been analyzed in many works both within the standard model and beyond standard model framework. In this paper, we investigate the $B_c \to D_s \nu\bar{\nu}$ decay channel which proceeds via the $b \to s \nu\bar{\nu}$ transition. We consider an effective Hamiltonian framework involving new physics currents. To explore these currents further, we also analyse the decay mode within the $V_2$ leptoquark model. In our analysis, we use the form factors that have been obtained in lattice QCD calculations. We then make predictions of the $B_c \to D_s \nu\bar{\nu}$ branching fraction both within the standard model and beyond.