QCD effective potential with strong magnetic fields
尾崎 翔
KEK
日時：2014年11月25日（火） 16:00-
場所：理学研究科合同B棟 7階 743号室
Recently, much attention has been paid to QCD under strong magnetic fields. It has been recognized that extremely strong magnetic fields are generated in relativistic heavy ion collisions. The magnitude of the magnetic field is thought to reach the QCD scale, Lambda_{QCD}. Such strong magnetic fields possibly affect hadron properties and QCD vacuum structures. Furthermore, it is a great theoretical advantage that lattice QCD can simulate strongly interacting quark and gluon system in the presence of strong magnetic fields without sign problem. As a first step towards understanding the effect of magnetic fields on QCD vacuum, we analytically derive the Euler-Heisenberg action for QCD+ QED at zero and finite temperatures [1]. From the action, we show an anisotropy of the QCD vacuum in strong magnetic fields. The action also show the gluonic magnetic catalysis, an enhancement of the gluon condensate with an increasing magnetic field. These results are consistent with recent lattice observations. At finite temperatures, we find that the magnetic field enhances the explicit breaking of the center symmetry of QCD [2]. This effect would reduce the (pseudo-) critical temperature of deconfinement phase transition, leading to inverse magnetic catalysis observed in current lattice data at finite temperatures [3]. [1] S. Ozaki, PRD89 (2014) 054022 [2] S. Ozaki, T. Arai, K. Hattori and K. Itakura in progress. [3] F. Bruckmann, G. Endrodi and T. G. Kovacs, JHEP 1304 (2013) 112