Inclusive $b \to \{u, c\} \, \ell^- \, \bar{\nu}_\ell$ modes: polarized/unpolarized $\Lambda_b$

TL;DR

This paper investigates inclusive semileptonic decays of polarized beauty baryons within the Standard Model and beyond, identifying observables sensitive to new physics, especially those related to baryon spin, relevant for future collider experiments.

Contribution

It extends the analysis of $ o U \, ell \, ar{ u}_ell$ decays to include polarization effects and new physics operators at $ ext{O}(1/m_b^3)$, providing novel observables for future experiments.

Findings

Analyzed polarized $$ decays with new physics operators.

Identified spin-dependent observables sensitive to beyond Standard Model effects.

Provided theoretical framework for future collider measurements.

Abstract

The increasing number of flavour anomalies motivates the investigation of new processes where tensions similar to the observed ones may emerge. It is necessary to identify observables sensitive to physics beyond the Standard Model. The analysis which follows concerns the inclusive semileptonic decays of polarized beauty baryons, computed through the Heavy Quark Expansion at $\mathcal{O}(1 / m_b^3)$ and at the leading order in $\alpha_s$. New Physics interactions have been taken into account, extending the Standard Model $b \to U \, \ell \, \bar{\nu}_\ell$ low-energy Hamiltonian, where $U = \{c, u\}$ and $\ell = \{e, \mu, \tau\}$, including the full set of $D = 6$ operators with left-handed neutrinos. Among the possible observables one can consider, the ones depending on the spin of the decaying baryon are very appealing and can be considered for physics programmes of future facilities, such as FCC-ee.