Implications of the fermion vacuum term in the extended SU(3) quark meson model on compact star properties

Abstract

We study the impact of the fermion vacuum term in the SU(3) quark meson model on the equation of state and determine the vacuum parameters for various sigma meson masses. We examine its influence on the equation of state and on the resulting mass radius relations for compact stars. The tidal deformability Λ of the stars is studied and compared to the results of the mean field approximation. Parameter sets which fulfill the tidal deformability bounds of GW170817 together with the observed two solar mass limit turn out to be restricted to a quite small parameter range in the mean field approximation. The extended version of the model does not yield solutions fulfilling both constraints. Furthermore, no first order chiral phase transition is found in the extended version of the model, not allowing for the twin star solutions found in the mean field approximation.

Interpreting binary neutron star mergers: describing the binary neutron star dynamics, modelling gravitational waveforms, and analyzing detections

“…A NS has a rich spectrum of modes. Those with sufficiently low frequencies could be tidally excited during an inspiral and yield spectroscopic information about matter in NS interiors; several examples have been studied to date [27,216,270,300,317,437,448,493,528,529,561]. Effects from nonlinear mode coupling have also been studied [200,323,550].…”

The slope, the hill, the drop, and the swoosh: Learning about the nuclear matter equation of state from the binary Love relations

“…Fig. 2 in [9] and [8,17,19,34,35,39,40,[45][46][47][48][49][50][51][52][61][62][63][64][65][66][67][68][69][70][71][72][73]. Reason (ii) could be related to first-order phase transitions [38,44,52,[74][75][76][77][78] or an "unphase transition", as predicted by the quarkionic model [35,40,42,48,79,80] or crossover transitions/Gibbs constructions to/with (stiff) quark matter [36,37,45,51,[81][82][83]…”

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“…In order to compare the results of our analysis with current available data on NS radii, we calculated the radii distributions for two different pulsars: PSR J0030+0451 (M = 1.44 +0. 15 −0.14 M ) and PSR J0740+6620 (M = 2.08 +0.07 −0.07 M ), whose masses have been recently evaluated experimentally using relativistic Shapiro time delay measurements [77,78]. The radii of these two pulsars have been estimated via X-ray measurements with the NICER telescope [76,[79][80][81].…”

“…In the absence of a satisfactory and controlled computation of the EoS from first-principle QCD with quark and gluonic degrees of freedom [10,11], a large number of phenomenological approaches has been proposed, such as bag models, the quark-meson coupling model and Nambu-Jona-Lasinio (NJL) models [12][13][14][15][16][17][18][19][20][21][22], all dependent on different and largely unconstrained parameters. To appreciate the model dependence of the predictions, it is therefore very important to perform studies where the parameter space is largely studied, at least in the framework of a specific effective approach [23][24][25].…”