Amplitude analysis of the $\Lambda^+_c\to pK^-\pi^+$ decay and $\Lambda^+_c$ baryon polarization measurement in semileptonic beauty hadron decays

TL;DR

This paper presents an amplitude analysis of the $\Lambda^+_c o pK^-\pi^+$ decay and measures the $\Lambda^+_c$ polarization in semileptonic beauty decays, providing detailed resonance parameters and demonstrating high sensitivity to polarization.

Contribution

It introduces a comprehensive amplitude model for $\Lambda^+_c$ decay analysis and measures $\Lambda^+_c$ polarization, enabling future polarization studies in similar systems.

Findings

Resonance fractions and decay parameters reported

Mass and width of $\Lambda(2000)$ determined

Significant $\Lambda^+_c$ polarization observed

Abstract

An amplitude analysis of $\Lambda^+_c \to pK^-\pi^+$ decays together with a measurement of the $\Lambda^+_c$ polarization vector in semileptonic beauty hadron decays is presented. A sample of $400\,000$ candidates is selected from proton-proton collisions recorded by the LHCb detector at a center-of-mass energy of 13 TeV. An amplitude model is developed and the resonance fractions as well as two- and three-body decay parameters are reported. The mass and width of the $\Lambda(2000)$ state are also determined. A significant $\Lambda^+_c$ polarization is found. A large sensitivity of the $\Lambda^+_c \to pK^-\pi^+$ decay to the polarization is seen, making the amplitude model suitable for $\Lambda^+_c$ polarization measurements in other systems.