# Departmental Seminar

## Hybrid stars using the quark-meson coupling and proper-time Nambu-Jona-Lasinio models

**Dr Daniel Whittenbury**

**Monday 30 May 2016 11am–12.30pm**

**Department Nuclear Physics Seminar Room**

At high density deconfinement of hadronic matter may occur leading to quark matter. The immense densities reached in the inner core of massive neutron stars may be sufficient to facilitate the transition.

In this talk I will discuss recent work investigating a crossover transition between two phenomenological models which epitomize quantum chromodynamics in two different regimes, while incorporating the influence of quark degrees of freedom in both.

We use the Hartree–Fock quark-meson coupling model and the proper–time regularized three–flavor Nambu–Jona–Lasinio model to describe hadronic and quark matter, respectively. Hybrid equations of state are obtained by interpolating the energy density as a function of total baryonic density and calculating the pressure. Equations of state for hadronic, quark, and hybrid matter and the resulting mass versus radius curves for hybrid stars will be shown, as well as other relevant physical quantities such as species fractions. The observations of massive neutron stars can certainly be explained within such a construction. However, the so-called thermodynamic correction arising from an interpolation method can have a considerable impact on the equation of state.