I will discuss the density matrix, entanglement entropy and their small x evolution in a color glass condensate (CGC). Specifically I will show that the CGC density matrix is diagonal in the quasiparticle basis, where it has the Boltzmann form. The quasiparticles in a wide interval of momenta behave as massless two-dimensional bosons with the temperature proportional to the typical semihard scale. I will argue that the semihard momentum region arises as a well-defined intermediate regime between the perturbatively hard momenta and the nonperturbative soft momenta in the CGC description of a hadronic wave function.
Nobuyuki Matsumoto