Theoretical Physics Colloquium

Magnetic susceptibility of QCD matter

by Prof. Gunnar Bali (Universitaet Regensburg, Germany)

Tuesday, February 18, 2020 from to (Asia/Kolkata)
at AG 69
Description While magnetic field strengths created in solid state physics laboratory experiments do not exceed 106 Gauss, corresponding to (40eV)2, much stronger fields can be present in compact astrophysical objects like magnetars or during neutron star mergers as well as in heavy ion collisions. These fields are so strong that in their presence the properties of strongly interacting matter will change, possibly with observable consequences.

I will describe theoretical expectations relating to matter in such environments. These have mostly been obtained by lattice QCD simulations. QCD matter turns out to be diamagnetic at low temperatures and paramagnetic at high temperatures. The magnetic susceptibility can be decomposed into a Pauli spin contribution and angular momentum related Landau contributions. Most intriguingly and contrary to conventional solid state materials, it is the Pauli term which is repsonsible for the diamagnetism at low temperatures.