CP Violation of Baryon Decays with $N\pi$ Scatterings

TL;DR

This paper proposes a model-independent method to analyze CP violation in baryon decays via $N ext{--}\pi$ scatterings, predicting observable CPV effects of several percent, potentially leading to the first experimental detection.

Contribution

It introduces a novel approach using $N ext{--}\pi$ scattering data to predict CP violation in baryon decays without relying on non-perturbative dynamics.

Findings

Global CPV in studied processes is several percent.

Local CPV can reach 10% or more in Dalitz plot regions.

Suggested experimental measurement could observe CPV in $ ext{Lambda}_b^0$ decays.

Abstract

There is a long-standing puzzle that the CP violation (CPV) in the baryon systems has never been well established in experiments, while the CPV of mesons have been observed by decades. In this paper, we propose that the CPV of baryon decays can be generated with the rescatterings of a nucleon and a pion into some final states, i.e. $N\pi\to N\pi$ or $N\pi\pi$. Benefited by the fruitful data of $N\pi$ scatterings, we can model-independently analyse the strong phases of $b$-baryon decays using the partial wave amplitudes of $N\pi$ scatterings. Avoiding the most difficult problem of non-perturbative dynamics, it makes a great advantage to predict the CPV of baryon decays with a relatively reliable understanding of the decay dynamics. We study the processes of $\Lambda_b^0\to (p\pi^+\pi^-)h^-$ and $(p\pi^0)h^-$ with $h=\pi$ or $K$. It is found that the global CPV of the above processes in the invariant mass regions of $N\pi$ scatterings are at the order of several percent. More importantly, the local CPV in some regions of the Dalitz plots can reach the order of $10\%$, or be even larger. Considering the predicted results and the experimental data samples, we strong suggest to measure the CPV of $\Lambda_b^0\to (p\pi^+\pi^-)K^-$, which has a large possibility to achieve the first observation of CPV in the baryon system.