Valeriya Mykhaylova (IFT)

Shear viscosity of the QGP from the relaxation time approximation within the quasiparticle model

It is known that the quark-gluon plasma is well described in terms of perfect fluid dynamics [1]. Besides, it is a common fact that there is nothing perfect in the world (although one should try - LT :-) ). Therefore, one needs to include dissipative processes, which are described by transport coefficients, into the QGP dynamics. I will present the shear viscosity obtained from the relaxation time approximation of the Boltzmann equation. The calculations are performed within the quasiparticle model, where dynamical quark and gluon masses depend on the lattice data [2]. [1] E. Shuryak, Prog. Part. Nucl. Phys. 53 (2004) [2] S. Borsanyi et al., Phys. Lett. B 370 (2014) 99-104

Sala 422 12:15 

dr hab. Brynmore Haskell (CAMK Warsaw)

Probing fundamental physics with multi-messenger observations of neutron stars

Neutron stars are an extraordinary laboratory for probing fundamental physics in extreme conditions that cannot be reproduced in terrestrial experiments. Not only are the core of these stars denser than atomic nuclei, but their thermal energies are small compared to the Fermi energies of their degenerate constituents. In these conditions it is favourable for Fermions (mostly, but not only, neutrons in most of the star) to pair and become superfluid. Superfluidity adds a new dimension to the problem, as components can now flow relative to each other and additional degrees of freedom become available. Strikingly, these microphysical properties can have large scale, astrophysical consequences. Superfluidity is thought to be at the heart of glitches, sudden spin-ups observed in radio pulsars, and is likely to play an important role in the physics of gravitational wave emission. In this talk I will present recent advances in theoretical modelling of neutron star superfluids, and discuss observational tests that can constrain the models, in particular observations of radio pulsars and gravitational wave observations with Advanced LIGO and Virgo.