The effects of polarization on the observables in the decay $\Xi_{cc}^{++} \rightarrow \Xi_{c}^{+} \bar{\ell}\nu_{\ell}$

TL;DR

This paper studies how polarization affects various measurable quantities in the decay of a doubly charmed baryon, providing insights into Standard Model tests through detailed polarization-dependent observables.

Contribution

It introduces a comprehensive analysis of polarization effects on decay observables using QCD sum rule form factors, including new polarization ratios and the lepton flavor universality ratio.

Findings

Polarization significantly influences decay observables.

The study provides detailed predictions for polarization asymmetries.

The lepton flavor universality ratio shows sensitivity to polarization effects.

Abstract

We investigate the effects of polarization on several physical observables in the semileptonic decay $\Xi_{cc}^{++} \rightarrow \Xi_c^{+} \bar{\ell}\nu_{\ell}$. We analyze the polarization effects of the particles involved in the decay, namely $\Xi_{cc}^{++}$, $\Xi_c^{+}$, and the charged muon $\ell$. Using the form factors obtained from QCD sum rules, we compute the $q^{2}$-dependent observables including the differential branching ratio, forward-backward asymmetry, and polarization asymmetries for both longitudinal and transverse polarization states. We also define and examine several polarization ratios and discuss correlations among different observables. In addition, we evaluate the lepton flavor universality ratio defined as $\mathcal{R}_{\Xi_c^+}(\mu/e) \equiv \mathcal{D}(\Xi_{cc}^{++}\to \Xi_c^+\mu^+\nu_\mu)/\mathcal{D}(\Xi_{cc}^{++}\to \Xi_c^+e^+\nu_e)$ and analyze its behavior over the available dynamical range. Our results show that these observables are quite sensitive to polarization effects a study of which provides excellent probes for testing the Standard Model.