Production of $K^* \Sigma$ and $D^* \Sigma_c$ in pion-induced reactions off the nucleon

TL;DR

This paper models strangeness and charm production in pion-induced reactions using a hybrid Regge approach, successfully matching data for strangeness and predicting suppressed charm cross sections for future experiments.

Contribution

It introduces a hybrid Regge framework combining effective Lagrangian vertices with Reggeized exchanges to analyze these reactions, including resonance contributions.

Findings

Good agreement with existing data for strangeness production cross sections.

Identification of the $ ext{Delta}(2150)1/2^-$ resonance as dominant near threshold.

Predicted charm production cross sections are significantly suppressed compared to strangeness.

Abstract

We investigate the mechanisms of strangeness production in the $\pi^- p \to K^{*0} \Sigma^0$ and $\pi^- p \to K^{*+} \Sigma^-$ reactions within a hybrid Regge framework in which effective Lagrangian vertices are combined with Reggeized exchanges. The nonresonant background consists of $t$-channel $K$- and $K^*$-Reggeon exchanges, $s$-channel nucleon and $\Delta$ exchanges, and $u$-channel $\Sigma$- and $\Lambda$-Reggeon exchanges, whose roles differ markedly between the two isospin channels. We additionally include several $N^*$ and $\Delta^*$ resonances in the $s$ channel and find that the $\Delta(2150)1/2^-$ resonance provides the dominant near-threshold contribution. The resulting total and differential cross sections and spin-density matrix elements (SDMEs) are in good agreement with the available data. Additional measurements near threshold ($W \lesssim$ 2.5 GeV) would be valuable for clarifying the role of $s$-channel baryon resonances. Within the same framework, with Regge trajectories and energy-scale parameters fixed by a QGSM-motivated prescription, we also predict the cross sections for the charm-production reactions $\pi^- p \to D^{*-} \Sigma_c^+$ and $\pi^- p \to D^{*0} \Sigma_c^0$. Their total cross sections are suppressed by approximately $4$--$5$ and $7$--$8$ orders of magnitude, respectively, compared with those of the corresponding strangeness-production reactions. These results may serve as useful guidance for future experiments at facilities such as J-PARC.