http://arxiv.org/abs/1802.06685
Compact stellar objects offer deep insight into the physics of elementary particles in dense environments through the imprint left by merger events on the electromagnetic and gravitational wave spectra. The theoretical description of compact star interiors requires full knowledge of the equation of state (EoS) of nuclear matter and involves the non-perturbative solution of quantum chromodynamics (QCD), the theory of strongly interacting quarks and gluons. However, first-principle methods (most notably, lattice QCD simulations) are not available for high neutron densities – consequently, the EoS of neutron stars necessarily relies on a modeling of the nuclear force. Here we propose a different scenario, where the neutron density vanishes and a Bose-Einstein condensate of charged pions (the lightest excitations in QCD) plays the central role instead. This setting can be approached by first-principle methods and leads to a new class of compact stars: pion stars. As we demonstrate, pion star matter exhibits gravitationally bound configurations and is metastable against electroweak decays. If pion stars indeed exist in our Universe, this result constitutes the first occasion that the EoS and the mass-radius relation of a compact stellar object is determined from first principles within the Standard Model.
B. Brandt, G. Endrodi, E. Fraga, et. al.
Tue, 20 Feb 18
21/54
Comments: 6 pages, 4 figures