arXiv subjects

Katsuyoshi Sone

Publications and source records attributed to Katsuyoshi Sone.

9 recordsLinked to original sources

arXiv2026

Isospin-breaking effects on the threshold cusp structures in $ΛN$-$ΣN$ scattering

We discuss the isospin-breaking effects on threshold cusp structures in multichannel scattering near two-body thresholds. In hadronic systems with isospin symmetry, two or more nearly degenerate thresholds can appear, and their small splitting due to isospin breaking can generate multiple cusp structures in a narrow energy region. In this paper, using the $K$-matrix representation, we derive a general expression for the scattering amplitude near the thresholds and show that the cusp structures can be classified by the signs of the slopes of the cross section above and below threshold. We also show that additional restrictions appear in two- or three-channel systems and in the Flatté amplitude. For three-channel scattering with two nearby thresholds, we clarify how the two cusp structures are related when the threshold splitting is small and how they merge into a single cusp in the degenerate limit. Finally, we discuss the cusp structures in the $Λp$ elastic cross section in the coupled $ΛN$-$ΣN$ system with charge $Q=+1$. We show that, when isospin breaking is small, the two cusp structures are constrained by isospin symmetry. We also perform quantitative calculations using both simplified examples and realistic input based on N$^2$LO chiral effective field theory, and find that isospin breaking can significantly modify the relative sharpness of the cusps and may even change the cusp type itself.

hep-ph↗

arXiv2026

Threshold Cusp Structures in the Presence of Isospin Symmetry Breaking

We study the behavior of the cusp structures focusing on the isospin-breaking effects. The properties of the near-threshold exotic hadrons are encoded in the shapes of the cusp structures. In hadron scattering, it is often the case that the thresholds of isospin partner channels are located within a narrow energy region. To analyze the scattering in such systems, it is therefore essential to study the cusp structures that emerge at two closely separated thresholds with isospin symmetry breaking. In this study, we propose a practical representation of the scattering amplitude and show that the two neighboring cusp structures are related through the isospin symmetry.

hep-ph↗

arXiv2026

Entanglement suppression for $ΩΩ$ scattering

We study entanglement suppression in $s$-wave $ΩΩ$ scattering, where each baryon has spin $3/2$. By treating the $S$-matrix as a quantum operator acting on the spin states, we quantify its ability to generate entanglement and identify the conditions on the phase shifts of the spin channels that minimize entanglement generation in the system. In $ΩΩ$ scattering, only antisymmetric spin channels are allowed due to Fermi-Dirac statistics. Applying the entanglement-suppression framework to $ΩΩ$ scattering, we find two solutions for the phase shifts: one leading to a spin SU(4) symmetry and the other to a nonrelativistic conformal symmetry. We show that the solution associated with the nonrelativistic conformal symmetry originates from the specific structure of the Clebsch-Gordan coefficients in the $3/2 \otimes 3/2$ system.

hep-ph↗

arXiv2025

Entanglement Suppression, Quantum Statistics and Symmetries in Spin-3/2 Baryon Scatterings

We explore the interplay among entanglement suppression, quantum statistics and enhanced symmetries in the non-relativistic $S$-wave scattering involving the lowest-lying spin-3/2 baryons, which can be considered as four-dimensional qudits. These baryons form a ten-dimensional representation (decuplet) under the $\text{SU}(3)$ light-flavor symmetry and, in this limit, are considered indistinguishable under strong interactions. Treating the $S$-matrix in the spin-3/2 baryon-baryon scattering as a quantum logic gate in the spin space, we study the consequence of entanglement suppression and compute the entanglement power of the $S$-matrix. When the entanglement power vanishes, the $S$-matrix is either an Identity or a SWAP gate and spin-flavor symmetries and/or non-relativistic conformal invariance emerge, as previously observed in spin-1/2 baryons. In the case of scattering identical particles, the entanglement power never vanishes due to constraints from spin statistics, which we interpret as projection-valued measurements onto symmetric or antisymmetric Hilbert space and define the entanglement power accordingly. When the entanglement power is non-vanishing but sits at a global or local minimum, enhanced symmetries still emerge and the $S$-matrix can be interpreted as an Identity or a SWAP gate acting on the restricted Hilbert space allowed by quantum statistics. In general, when scattering identical spin-$s$ particles, we identify an enhanced $\text{SU}(2s+1)_{\text{spin}}$ symmetry for the Identity gate.

hep-ph↗

arXiv2025

Entanglement suppression and emergent symmetries in hadron scatterings

Recently entanglement suppression was proposed to be one potential origin of emergent symmetries. In this work, we extend this theoretical framework to accommodate particles with arbitrary spins and/or arbitrary group representations. As case studies, we discuss recent efforts to test the entanglement-suppression conjecture in two hadron systems that exhibit possible emergent symmetries. The first concerns interactions involving spin-3/2 baryons, where entanglement suppression gives rise to symmetries such as $\text{SU}(40)$ spin-flavor symmetry. The second system involves low-energy scattering of heavy mesons, where entanglement suppression leads to an enhancement of the inherent heavy-quark spin symmetry to a light-quark spin symmetry, predicting additional siblings for the prominent exotic double-charm meson $T_{cc}(3875)^+$. These predictions should be confronted against experimental data and lattice results to further test the minimal-entanglement conjecture.

hep-ph↗

arXiv2025

Threshold cusp structures in multi-channel scattering

We study the behavior of the cusp structures focusing on the isospin symmetry breaking effects. The properties of the exotic hadrons are reflected in the shape of the cusp structures. In realistic hadron scatterings, the threshold energies of the isospin partners appear within a small energy region. For a detailed analysis of such systems, it is essential to study the behavior of the cusp structures arising at two closely spaced thresholds. In this work, we introduce a convenient formulation of the scattering amplitude and demonstrate that the cusp structures at two nearby thresholds are related through the isospin symmetry.

hep-ph↗

arXiv2025

General behavior of near-threshold hadron scattering for exotic hadrons

We discuss the general behavior of the near-threshold scattering amplitude with channel couplings. The signal of the exotic hadrons near the threshold may manifest as a dip structure in the cross section originated from a zero point of the scattering amplitude. Such a dip structure by the zero point cannot be reproduced by the Flatté amplitude which is widely used for the analysis of exotic hadrons, because of the constraints imposed on the Flatté amplitude near the threshold. In this work, we propose the General amplitude which can describe the dip structure near the threshold, in contrast to the Flatté amplitude. Moreover, we numerically study the behavior of the near-threshold cross section in relation to the zero point.

hep-ph↗

arXiv2024

General amplitude of near-threshold hadron scattering for exotic hadrons

We discuss the general behavior of the scattering amplitude with channel couplings near the two-body threshold. It is known that the Flatté amplitude, which is often used in the analysis of experimental data involving exotic hadrons, has some constraint in the near-threshold energy region. While the M-matrix gives the general expression of the scattering amplitude, it is not smoothly connected to the Flatté amplitude, due to the property of the determinant of the amplitude in channel space. In this paper, based on the effective field theory, we propose new parametrization of the scattering amplitude which gives the general expression near the threshold and has a well-defined limit reproducing the Flatté amplitude. We show that the nonresonant background contribution exists in the general amplitude even in the first order in the momentum. Finally, we quantitatively evaluate the cross sections by changing the strength of the background contribution. We find that the interference with the background term may induce a dip structure of the cross section near the threshold, in addition to the peak and threshold cusp structures.

hep-ph↗

arXiv2023

Near-threshold hadron scattering with effective field theory

When an exotic hadron locates near the threshold with the channel couplings, the internal structure of the exotic hadron is related to the scattering length. To incorporate the threshold effect, the Flatté amplitude has been often used to determine the scattering length. It is however known that an additional constraint is imposed on the Flatte amplitude near the threshold. We discuss this problem by using the effective field theory for the coupled-channel scattering.

hep-ph↗