Speed of sound exceeding the conformal bound in dense QCD-like theories

2025/11/28 by Itou, Etsuko, Iida, Kei, Murakami, Kotaro +1
#FOS: Physical sciences #High Energy Physics - Lattice (hep-lat) #High Energy Physics - Phenomenology (hep-ph) #Nuclear Theory (nucl-th)

paper · doi:10.48550/arxiv.2511.22878

Abstract

We investigated the phase structure and the equation of state (EoS) for dense two-color QCD at low temperatures using the lattice Monte Carlo simulations. A rich phase structure below the pseudo-critical temperature T_c as a function of quark chemical potential has been revealed. In a high-density regime, we can see a superfluid phase, where the diquark condensate takes a non-zero expectation value. We have newly found that the speed of sound exceeds the conformal bound, which is the value of the relativistic free theory. This talk is based on Refs.~\citeIida:2022hyy, Iida:2024irv, Itou:2025vcy.

Citations

• Speed of sound peak in two-color dense QCD: Confronting effective models with lattice data
• Lattice results for the equation of state in dense QCD-like theories
• Speed of sound peak in isospin QCD: a natural prediction of the Medium Separation Scheme
• Dense QC₂D. What's up with that?!?
• 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
• Interplay between the weak-coupling results and the lattice data in dense QCD
• Lattice study on finite density QC₂D towards zero temperature
• Velocity of Sound beyond the High-Density Relativistic Limit from Lattice Simulation of Dense Two-Color QCD

Related

• Speed of sound exceeding the conformal bound in dense 2-color QCD
• Lattice results for the equation of state in dense QCD-like theories
• Bump of sound velocity in dense 2-color QCD
• Velocity of Sound beyond the High-Density Relativistic Limit from Lattice Simulation of Dense Two-Color QCD
• Speed of sound peak in two-color dense QCD: Confronting effective models with lattice data