Sizable Time-reversal violating effects in bottom baryon decays

TL;DR

This paper investigates time-reversal asymmetries in bottom baryon decays, predicting large T-violating effects in certain channels within the Standard Model, which are measurable at LHCb.

Contribution

It provides theoretical predictions of sizable T-violating effects in specific bottom baryon decay channels, highlighting measurable parameters for experimental verification.

Findings

Large T-odd parameters (~40% and -25%) in certain decay channels.

Sizable helicity amplitudes leading to observable T-violation.

Suppressed T-violation in vector meson decay channels.

Abstract

We study time-reversal~(T) asymmetries in the charmless two-body decays of antitriplet bottom baryons. We find that in ${\bf B}_b \to {\bf B}_n P$ with ${\bf B}_b = (\Xi _b ^- , \,\Xi_b^0, \,\Lambda_b)$ and ${\bf B}_n(P)$ a octet baryon (pseudoscalar meson), the positive and negative helicity amplitudes are both sizable, resulting in the large T-violating effects. Particularly, the T-odd parameters, $\beta_w$, for the color-enhanced channels are expected to be around $40\%$ and $-25\%$ in $b\to s $ and $b\to d $ transitions for the standard model, which can be measured by the experiments at LHCb, respectively. On the other hand, in ${\bf B}_b \to {\bf B}_n V(\gamma)$ with $V(\gamma)$ a vector meson~(photon), the decays are predominated by a single helicity amplitude, and the T violating effects by the correlations among spins are suppressed. We also explore the T violating observables for the $\Xi_b$ decays based on the angular distributions.