Anisotropy of the quark-antiquark potential in a magnetic field
  We investigate the static $\overline{Q}Q$-potential for $N_f = 2+1$ QCD at the physical point in the presence of a constant and uniform external magnetic field. The potential is found to be anisotropic and steeper in the directions transverse to the magnetic field than in the longitudinal one. In particular, when compared to the standard case with zero background field, the string tension increases (decreases) in the transverse (longitudinal) direction, while the absolute value of the Coulomb coupling and the Sommer parameter show an opposite behavior. 
Claudio Bonati, Massimo D'Elia, Marco Mariti, Michele Mesiti,   Francesco Negro and Francesco Sanfilippo
hep-lat hep-ph hep-th