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Low-lying $Λ$ and $Σ$ resonances studied with the forward $K^{*}$ productions off the proton induced by a high-momentum $π$ beam

¹Research Center for Nuclear Physics, The University of Osaka, Ibaraki, Osaka 567-0047, Japan
²Physics Division, Argonne National Laboratory, Argonne, Illinois 60439, USA

^*Contact author: kamano@rcnp.osaka-u.ac.jp
^†Contact author: tshlee@anl.gov

Phys. Rev. C 114, 015205 – Published 16 July, 2026

DOI: https://doi.org/10.1103/7ffl-qytm

Abstract

We develop a novel model utilizing the forward $K^{*}$ production reaction off the nucleon, $π N \to K^{*} M B$ , induced by a high-momentum $π$ beam, as a tool to study low-lying $Y^{*}$ resonances below and just above the $\bar{K} N$ threshold. Because conventional $K^{-} p$ scattering experiments face difficulties in directly accessing this kinematic region, the proposed reaction offers a valuable complementary approach for $Y^{*}$ spectroscopy. The constructed model is based on the one-meson exchange mechanism, which is known to dominate forward-angle production at high energies, and the half-off-shell scattering amplitudes from the ANL-Osaka dynamical coupled-channels models (Model A and Model B). We predict various observables, including differential cross sections and angular distributions. Our results demonstrate significant enhancements in the sub-threshold region of the invariant mass spectra. Notably, we show that overlapping resonances, such as a potential new $3 / 2^{+} Σ$ state and the well-established $Σ (1385) 3 / 2^{+}$ , can constitute a single peak in the $π Λ$ mass spectrum, indicating that the existence of previously unconfirmed subthreshold states cannot be ruled out by analyzing only the existing mass spectrum data. Furthermore, we find that angular distributions provide strong discriminatory power to disentangle such overlapping states through partial-wave interference effects, while the $t^{'}$ and $ϕ_{M}^{*}$ dependencies provide crucial constraints on the high-energy production mechanisms. Our predictions for these highly sensitive observables can facilitate high-statistics measurements, which are accessible at modern hadron facilities such as J-PARC, to unravel the $S = - 1 Y^{*}$ mass spectrum.

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Phys. Rev. C 114, 015205– Published 16 July, 2026

Vol. 114, Iss. 1 — July 2026

Received 23 May 2026
Accepted 22 June 2026

DOI: https://doi.org/10.1103/7ffl-qytm

Published by the American Physical Society under the terms of the Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article's title, journal citation, and DOI. Funded by SCOAP³.

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Low-lying $Λ$ and $Σ$ resonances studied with the forward $K^{*}$ productions off the proton induced by a high-momentum $π$ beam

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Low-lying Λ and Σ resonances studied with the forward K* productions off the proton induced by a high-momentum π beam

Abstract

Physics Subject Headings (PhySH)

Article Text

References (28)

Low-lying $Λ$ and $Σ$ resonances studied with the forward $K^{*}$ productions off the proton induced by a high-momentum $π$ beam