QCD moat regime and its real-time properties
Wei‐jie Fu, Jan M. Pawlowski, Robert D. Pisarski, Fabian Rennecke, Rui Wen, Shi Yin
Abstract
Dense quantum chromodynamics (QCD) matter may exhibit crystalline phases. Their existence is reflected in a moat regime, where mesonic correlations feature spatial modulations. We study the real-time properties of pions at finite temperature and density in QCD in order to elucidate the nature of this regime. We show that the moat regime arises from particle-hole-like fluctuations near the Fermi surface. This gives rise to a characteristic peak in the spectral function of the pion at nonzero spacelike momentum. This peak can be interpreted as a new quasi particle, the moaton. In addition, our framework also allows us to directly test the stability of the homogeneous chiral phase against the formation of an inhomogeneous condensate in QCD. We find that an inhomogeneous instability is highly unlikely for baryon chemical potentials <a:math xmlns:a="http://www.w3.org/1998/Math/MathML" display="inline"> <a:mrow> <a:msub> <a:mrow> <a:mi>μ</a:mi> </a:mrow> <a:mrow> <a:mi>B</a:mi> </a:mrow> </a:msub> <a:mo>≤</a:mo> <a:mn>630</a:mn> <a:mtext> </a:mtext> <a:mtext> </a:mtext> <a:mi>MeV</a:mi> </a:mrow> </a:math> .