Photon signals from quarkyonic matter.

Area of Science:

• High-energy nuclear physics
• Quantum chromodynamics (QCD) phase diagram
• Particle astrophysics

Background:

• Understanding the QCD phase diagram at high baryon densities is crucial for nuclear physics.
• Quarkyonic matter is a proposed phase of nuclear matter existing at high densities and moderate temperatures.
• Distinguishing between quark-gluon plasma, quarkyonic matter, and hadron gas phases is experimentally challenging.

Purpose of the Study:

• To calculate the bremsstrahlung photon spectrum emitted from dynamically evolving quarkyonic matter.
• To compare the photon spectrum of quarkyonic matter with that of quark-gluon plasma and hadron gas.
• To identify potential signatures of quarkyonic matter in particle production.

Main Methods:

• Calculation of the photon spectrum using dynamical evolution models.
• Comparative analysis of transverse momentum distributions and harmonic coefficients (elliptic flow).
• Investigation of event-by-event fluctuations in the elliptic flow coefficient.

Main Results:

• The transverse momentum distribution of quarkyonic matter is markedly steeper than that of quark-gluon plasma or hadron gas.
• Quarkyonic matter exhibits random fluctuations in its elliptic flow coefficient, both event-by-event and within the same event.
• These fluctuations are linked to quark wave function shapes within quarkyonic matter.

Conclusions:

• The distinct transverse momentum spectrum and elliptic flow fluctuations can serve as potential signatures for quarkyonic matter.
• These signatures are most prominent at lower temperatures where the quarkyonic regime dominates.
• Separating reaction-plane flow from fluctuating components is necessary for definitive identification.