Magnetic susceptibility at zero and nonzero chemical potential in QCD and QED

Understand

Magnetic susceptibility of the quark matter in QCD is calculated in a closed form for an arbitrary chemical potential \mu.

• For small \mu, \mu<<T, eB << T^2, a strong dependence on temperature T is found due to Polyakov line factors.
• In the opposite case of small T, eB > T^2, the oscillations as functions of eB occur, characteristic of the de Haas-van Alphen effect.
• Results are compared with available lattice data.