Strange matter in compact stars

¹ Department of Physics and Astronomy, California State University Long Beach, California 90840, U.S.A
² Institute of Theoretical Physics, University of Wrocław, pl. M. Borna 9, 50-204 Wroclaw, Poland
³ Bogoliubov Laboratory of Theoretical Physics JINR Dubna, Joliot-Curie str. 6, 141980 Dubna, Russia
⁴ National Research Nuclear University (MEPhI), Kashirskoe Shosse 31, 115409 Moscow, Russia

^* e-mail: thomas.klaehn@csulb.edu ^** e-mail: david.blaschke@ift.uni.wroc.pl

Published online: 2 February 2018

Abstract

We discuss possible scenarios for the existence of strange matter in compact stars. The appearance of hyperons leads to a hyperon puzzle in ab-initio approaches based on effective baryon-baryon potentials but is not a severe problem in relativistic mean field models. In general, the puzzle can be resolved in a natural way if hadronic matter gets stiffened at supersaturation densities, an effect based on the quark Pauli quenching between hadrons. We explain the conflict between the necessity to implement dynamical chiral symmetry breaking into a model description and the conditions for the appearance of absolutely stable strange quark matter that require both, approximately masslessness of quarks and a mechanism of confinement. The role of strangeness in compact stars (hadronic or quark matter realizations) remains unsettled. It is not excluded that strangeness plays no role in compact stars at all. To answer the question whether the case of absolutely stable strange quark matter can be excluded on theoretical grounds requires an understanding of dense matter that we have not yet reached.