Work

Entanglement entropy for π + p elastic scattering using a spin-density matrix

Year: 2025

Type: article

Abstract: The π + p elastic scattering process is studied, using an effective Lagrangian approach that incorporates the s -, u -, and t -channel amplitudes, including Δ + + ( 1232 ) , Δ 0 ( 1232 ) , neutron, and ρ 0 contributions. By constructing the spin-density matrices from the scattering amplitudes, the von Neumann (entanglement) entropy is derived and associated with the spin degrees of freedom of the initial and final state particles. The entropy is computed by performing a partial trace over the spin subsystems, and its behavior is analyzed as a function of the center-of-mass energy W and scattering angle θ . It is found that entropy exhibits nontrivial angular and energy dependences, reflecting the interplay among resonance contributions and background amplitudes. In particular, the Δ + + region shows relatively low entanglement, suggesting spin coherence dominated by the specific resonant contribution, while the background contributions increase entropy due to mixed spin configurations. These results indicate that entanglement entropy can serve as a novel probe into the quantum structure of hadronic scattering amplitudes, providing complementary insights beyond conventional cross-section analyses.

Source: Physical Review C

DOI: 10.1103/7vps-vt18

Author: Seung-il Nam

Institution: Pukyong National University

Language: English

Topic: Quantum Chromodynamics and Particle Interactions

Subfield: Nuclear and High Energy Physics

Field: Physics and Astronomy

Domain: Physical Sciences

Open Access status: hybrid

Funders: Japan Science and Technology Corporation, National Research Foundation of Korea, Japan Society for the Promotion of Science

Awards: G2415435923, G2538555585, G6064048098, Theoretical study of cluster structure of light nuclei based on realistic nuclear force