Thermal QCD spectrum and potential: bottomonium at non-zero temperature

Abstract

The spectrum and potential of bottomonium mesons offer windows into strong force phenomenology. This thesis investigates these two constructs at non-zero temperature to explore thermal modifications of bound states. Lattice simulations are performed on two generations of the FASTSUM ensembles using a nonrelativistic effective field theory of quantum chromodynamics, NRQCD. These ensembles contain 2+1 flavours of dynamical sea quarks at temperatures spanning the pseudocritical temperature. Maximum likelihood estimation is used to recover the spectrum of two representative bottomonium states, Υ and χb1, from which the ground state mass and width are determined at non-zero temperature. The central and spin-dependent potentials between the bottom quark and antiquarkare calculated using the approach from the HAL QCD collaboration. The standard implementation is used and then significant improvements are presented that provide a validation of the use of the non-relativistic Schrödinger equation at non-zero temperature.