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arXiv · 2602.14113

Quarkyonic matter and hadron-quark crossover from an ultracold atom perspective

Hiroyuki Tajima·Kei Iida·Toru Kojo·Haozhao Liang
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Abstract

The dense matter equation of state is of great interest due to the recent development of astrophysical observations for neutron stars. A rapid increase in pressure indicates a continuous crossover from a hadron phase to a quark phase without any phase transitions, yet its microscopic mechanism remains elusive. Recently, a peak in the speed of sound and a baryon momentum-shell structure, which are predicted from a quarkyonic matter picture, have been regarded as key features of the hadron-quark crossover. In this work, we explore a field-theoretical framework to describe the hadron-quark crossover, drawing an analogy with the Bose-Einstein condensate to Bardeen-Cooper-Schrieffer (BEC-BCS) crossover established in ultracold atomic experiments. Strikingly, a peak in the speed of sound and the baryon momentum-shell structure can simultaneously be explained by the tripling fluctuation effect arising from a different context of quantum many-body physics. We demonstrate these properties in a simplified model and provide a microscopic derivation of the quarkyonic matter model within our field-theoretical framework.

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Hiroyuki Tajima, Kei Iida, Toru Kojo, Haozhao Liang. 2026-02-15. Quarkyonic matter and hadron-quark crossover from an ultracold atom perspective. https://doi.org/10.1088/1361-6382/ae6601

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