Chemical and mechanical instability in warm and dense nuclear matter

TL;DR

This paper explores the thermodynamic instabilities and phase transition from nucleonic to Delta-matter in warm, dense nuclear matter, highlighting mechanical and chemical-diffusive instabilities similar to liquid-gas transitions.

Contribution

It provides a detailed analysis of the nucleon-Delta phase transition and compares the nature of mechanical and chemical instabilities in asymmetric nuclear matter.

Findings

Identification of mechanical and chemical-diffusive instabilities during the phase transition.

Characterization of the phase transition as similar to liquid-gas transition.

Analysis of the impact of asymmetry on nuclear matter stability.

Abstract

We investigate the possible thermodynamic instability in a warm and dense nuclear medium (T<50 MeV and \rho_0<\rho_B< 3\rho_0) where a phase transition from nucleonic matter to resonance-dominated Delta-matter can take place. The analysis is performed by requiring the global conservation of baryon and electric charge numbers in the framework of a relativistic equation of state. Similarly to the liquid-gas phase transition, we show that the nucleon-Delta matter phase transition is characterized by both mechanical instability (fluctuations on the baryon density) and by chemical-diffusive instability (fluctuations on the charge concentration) in asymmetric nuclear matter. We then perform an investigation and a comparative study on the different nature of such instabilities and phase transitions.