Speaker
Description
Hydrodynamic simulations of neutron star mergers require knowledge not only of the equilibrium properties of strongly interacting matter, but also of the system’s response to perturbations, encoded in various transport coefficients. Among the different transport coefficients, the bulk viscosity, which quantifies energy dissipation during a rapid compression or expansion of matter, stands out as particularly important. The leading contribution for the bulk viscosity of unpaired cold and dense quark matter comes from a W-boson exchange in the electroweak (EW) process u s → d u [1]. Currently this is known to leading order in the limit of massless quarks and small temperature [2].
Accounting for the mass of the strange quark as well as next-to-leading order QCD corrections can be expected to have a major contribution to the EW rate. In the perturbatively derived expression for the bulk viscosity in [1], the only major temperature dependance comes from the rate u s → d u. The other coefficients in the expression can be derived from knowledge of the equation of state. Thus, a precise knowledge of the EW rate directly translates to an improved understanding of quark matter bulk viscosity, and the detailed evaluation of these corrections is highly motivated. In this poster we focus on these topics.
[1] J. Cruz Rojas et al., arXiv 2402.00621 (2024)
[2] J. Madsen, Phys. Rev. D47, 325-330 (1993)
