Publication : t18/100

Abstract:
We construct an effective field theory approach to the equation of state (EoS) for nuclear and compact star matter entirely in terms of "effective" hadron degrees of freedom. The putative smooth transition at n∼(2−4)n0 (where n0 is the normal nuclear matter density) from hadron degrees of freedom to strongly-coupled quark degrees of freedom, presumably required for a soft-to-hard changeover in the EoS to account for the massive stars observed, is effectuated by the change at $n_{1/2}gsim 2n_0$ from skyrmions to half-skyrmions in a topological description of baryons. The mechanism exploits possible emergence of hidden scale and local symmetries of QCD at high density, leading to a precocious "pseudo-conformal" sound velocity v2s=1/3 (in unit of c=1). It offers an appealing possibility that the topology change density n1/2, accessible up to date neither by theory nor by terrestrial experiments, could be determined by the tidal deformability in gravity waves coming from coalescing neutron stars in LIGO/Virgo-type observations.

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