中性子星に現れる極限状態のクロスオーバー～物性理論による挑戦～

2025-07-24 東京大学

＜関連情報＞

• https://www.s.u-tokyo.ac.jp/ja/press/10876/
• https://journals.aps.org/prl/abstract/10.1103/4ywp-752m

フェルミオン物質における3倍の変動とピーク音速 Tripling Fluctuations and Peaked Sound Speed in Fermionic Matter

Hiroyuki Tajima, Kei Iida, Toru Kojo, and Haozhao Liang
Physical Review Letters  Published: 23 July, 2025
DOI: https://doi.org/10.1103/4ywp-752m

Abstract

A crossover involving three-fermion clusters is relevant to the hadron-quark crossover, which, if occurring in a neutron star, could naturally reproduce the dense-matter equation of state recently deduced from simultaneous observations of neutron-star masses and radii. To understand the crossover mechanism, we examine the role of tripling fluctuations induced by the formation of three-fermion clusters. The phase-shift representation of fluctuations manifests an interplay of bound and scattering states, leading to nonmonotonic momentum distributions of baryonlike clusters and peaked sound speed at finite densities. We demonstrate them by applying our approach to a nonrelativistic system of one-dimensional three-color fermions analogous to the hadron-quark matter.