2018-07-13  P7F

Gauge-invariant-canonical and mechanical orbital-angular-momentum in Landau problem.

Yoshio Kitadono

Attempts to understand the nucleon spin in terms of quarks and gluon in QCD have been carried out for a long time. In particular, recently, Chen et al proposed the new decomposition of nucleon spin in 2008 and their decomposition is based on longitudinal/transverse decomposition of gluon field. Their proposal arose many debates and currently two-different-gauge-invariant decompositions of nucleon spin are known. One of the decomposition is gauge-invariant-canonical decomposition and the another is mechanical decomposition. In this talk, we try to clarify which decomposition corresponds to physical observables, by testing the idea of these two decompositions in the well known system called Landau problem, namely, quantum mechanics of an electron in a uniform magnetic field. We claim that mechanical decompositions correspond to physical quantities and we will explain a reason why we can think so.

  Presentation Slides