In this work we investigate the minimal physical requirements needed for generating a speed of sound that surpasses its asymptotic conformal limit. It is shown that a peak in the speed of sound of homogeneous matter naturally emerges in the transition from a phase with broken chiral symmetry to one with a gapped Fermi surface. We argue that this could be relevant for understanding the peak in the speed of sound displayed by some of the current models for cold ultradense matter. A minimal model implementation of this mechanism is presented, based on the spontaneous breakdown of an approximate particle-antiparticle symmetry, and its thermodynamic properties are determined.
Which Neutron Stars Reach the Stiffening Regime? Multimessenger Constraints on Core Sound Speed and Stellar-Mass Thresholds
Universidad Técnica Federico Santa María（费德里科·Santa María技术大学）；Millennium Institute for Subatomic Physics at the High-Energy Frontier (SAPHIR)（高能前沿亚原子物理千年研究所）
Neutron star structure and nuclear matter properties from a general Walecka-type model with Bayesian analysis
School of Frontier Sciences, Nanjing University（前沿科学学院，南京大学）；School of Fundamental Physics and Mathematical Sciences, Hangzhou Institute for Advanced Study, UCAS（基础物理与数学学院，杭州高等研究院，中国科学院大学）
Speed of sound and trace anomaly in a unified treatment of the two-color diquark superfluid, the pion-condensed high-isospin matter, and the 2SC quark matter
Quarkyonic matter and hadron-quark crossover from an ultracold atom perspective
The University of Tokyo（东京大学）；RIKEN Nishina Center（理化学研究所仁科中心）；Quark Nuclear Science Institute, The University of Tokyo（东京大学夸克核科学研究所）；The Open University of Japan（日本开放大学）；High Energy Accelerator Research Organization (KEK)（高能加速器研究机构（KEK））；RIKEN Center for Interdisciplinary Theoretical and Mathematical Sciences（理化学研究所交叉理论与数学科学中心）
