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Production of $K^* Σ$ and $D^* Σ_c$ in pion-induced reactions off the nucleon

Sang-Ho Kim

Abstract

We investigate the mechanisms of strangeness production in the $π^- p \to K^{*0} Σ^0$ and $π^- p \to K^{*+} Σ^-$ 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 $Δ$ exchanges, and $u$-channel $Σ$- and $Λ$-Reggeon exchanges, whose roles differ markedly between the two isospin channels. We additionally include several $N^*$ and $Δ^*$ resonances in the $s$ channel and find that the $Δ(2150)1/2^-$ 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 $π^- p \to D^{*-} Σ_c^+$ and $π^- p \to D^{*0} Σ_c^0$. 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.

Production of $K^* Σ$ and $D^* Σ_c$ in pion-induced reactions off the nucleon

Abstract

We investigate the mechanisms of strangeness production in the and reactions within a hybrid Regge framework in which effective Lagrangian vertices are combined with Reggeized exchanges. The nonresonant background consists of -channel - and -Reggeon exchanges, -channel nucleon and exchanges, and -channel - and -Reggeon exchanges, whose roles differ markedly between the two isospin channels. We additionally include several and resonances in the channel and find that the 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 ( 2.5 GeV) would be valuable for clarifying the role of -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 and . Their total cross sections are suppressed by approximately -- and -- 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.

Paper Structure

This paper contains 9 sections, 57 equations, 12 figures, 3 tables.

Table of Contents

  1. Introduction
  2. Theoretical Framework
  3. Strangeness production: $\pi^- p \to K^* \Sigma$
  4. Charm production: $\pi^- p \to D^* \Sigma_c$
  5. $u$-channel hyperon-Reggeon exchange
  6. $s$-channel nucleon and $\Delta$ exchanges: $\pi^- p \to K^* \Sigma$
  7. $s$-channel $N^*$ and $\Delta^*$ exchanges: $\pi^- p \to K^* \Sigma$
  8. Numerical Results
  9. Summary and Conclusion

Figures (12)

  • Figure 1: Feynman diagrams for the $\pi^- p \to K^{*0} \Sigma^0 (D^{*-} \Sigma_c^+)$ reactions, including (a) $t$-channel pseudoscalar- and vector-Reggeon exchanges and (b) $u$-channel $\Sigma$ ($\Sigma_c$)-Reggeon exchange. For the $\pi^- p \to K^{*+} \Sigma^- (D^{*0} \Sigma_c^0)$ reactions, (c) denotes the $u$-channel hyperon-Reggeon exchange, where $Y^0 = (\Lambda,\Sigma)$ and $Y_c^+ = (\Lambda_c^+,\Sigma_c^+)$.
  • Figure 2: Quark-level diagram for the $\pi^- p \to K^{*0} \Sigma^0 (D^{*-} \Sigma_c^+)$ reactions in the $t$ channel.
  • Figure 3: Feynman diagram for the $\pi^- p \to K^* \Sigma$ reaction via $s$-channel $N^{(*)}$ and $\Delta^{(*)}$ exchanges.
  • Figure 4: Total cross sections as functions of $P_{\mathrm{Lab}}$ for the (a) $\pi^- p \to K^{*0} \Sigma^0$ and (b) $\pi^- p \to K^{*+} \Sigma^-$ reactions without resonance contributions. The green dotted, blue dashed, orange dash-detted-detted, magenta dash-dotted, and violet dash-dash-dotted curves represent the contributions from the $K$-, $K^*$-, $\Sigma$-, and $\Lambda$-Reggeon exchanges, and $\Delta$ exchange, respectively. The black solid curves denote the Born contributions. Experimental data are taken from Refs. Dahl:1967pg (squares), Miller:1965 (diamonds), CCMS:1980ysu (open triangles), and Crennell:1972km (open circles).
  • Figure 5: Total cross sections as functions of $W$ for the (a) $\pi^- p \to K^{*0} \Sigma^0$ and (b) $\pi^- p \to K^{*+} \Sigma^-$ reactions. The black dashed and magenta dash-dotted curves represent the Born and resonance contributions, respectively. The black solid curves denote the full results. Experimental data are taken from Refs. Dahl:1967pg (squares), Miller:1965 (diamonds), CCMS:1980ysu (open triangles), and Crennell:1972km (open circles).
  • ...and 7 more figures