# RIKEN Lunch Seminar

## "Complex spectrum of QCD at finite density"

#### Presented by Hiromichi Nishimura, RBRC

Thursday, October 6, 2016, 12:30 pm — Building 510, Room 2-160

We consider the effective action of the Polyakov loop at finite temperature and density. Using simple models, we show two novel manifestations of the sign problem in QCD: the non-hermitian transfer matrix and the complex saddle point. As a result the mass matrix associated with the Polyakov loop becomes complex, and it gives rise to damped oscillatory behavior in Polyakov loop correlation functions, which reflects oscillatory behavior in the quark-number density reminiscent of density-density correlation functions in liquids. The complex spectrum should be observable in lattice simulations of QCD and may provide a test for finite-density algorithms.

Hosted by: Hiroshi Oki

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