Multidimensional Resonance Analysis of $\Lambda_c^+ \to pK^-\pi^+$

TL;DR

This paper presents the first complete five-dimensional amplitude analysis of the $ ext{Lambda}_c^+ o pK^- ext{ extpi}^+$ decay system, measuring various resonant contributions and polarization effects using Fermilab data.

Contribution

It introduces the first comprehensive amplitude analysis of this decay channel, providing detailed measurements of resonant and nonresonant decay fractions and polarization behavior.

Findings

54.8% nonresonant decays

19.5% via $ar{K}^{*0}$ resonance

Evidence of polarization dependence on $p_T^2$

Abstract

We present the results of a five-dimensional resonant amplitude analysis of the $\Lambda_c^+{\to}pK^{-}\pi^{+}$ system based on $946\pm 38$ reconstructed decays. These data were produced in 500 GeV/$c$ $\pi^-$-N interactions by Fermilab experiment E791. We report measurements of the amplitudes for $\Lambda_c^+$ decay into nonresonant $pK^-\pi^+$ and to $p\bar{K}^{*0}(890)$, $\Delta^{++}(1232)K^-$, and $\Lambda(1520)\pi^+$ and we comment on other possible resonant enhancements. This is the first complete amplitude analysis of the $\Lambda_c^{+}{\to}pK^{-}\pi^{+}$ system. We find that $(54.8\pm5.5\pm3.5)$% of the decays are nonresonant, $(19.5\pm2.6\pm1.8)$% of the decays are via the $\bar{K}^{*0}$ resonance, $(18.0\pm2.9\pm2.9)$% of the decays are via the $\Delta^{++}$ resonance, and $(7.7\pm1.8\pm1.1)$% of the decays are via the $\Lambda(1520)$ resonance. We find evidence for an increasingly negative polarization of the $\Lambda_c^+$ baryons as a function of $p_T^2$, in agreement with a recent model\cite{dha} and with a related measurement\cite{jez}.