[RBRC Seminar] Grassmann Tensor Renormalization Group for 2-flavor massive Schwinger model with a theta term

by Dr Hayato Kanno (RBRC)

Thursday 5 Dec 2024, 12:30 → 13:45 US/Eastern

2-160 (https://bnl.zoomgov.com/j/1600983728?pwd=RAD7OLcqre7Ycsp6JfFp6HAnpyLxex.1)

QCD has been understood through numerical calculations using the Monte Carlo method. However, this method does not work for some parameter regions because of the sign problem. For example, QCD with a theta term has a sign problem, so the nature of QCD with a finite theta parameter is unknown. The theta dependence is also important to axion physics.
Tensor network methods are powerful tools to reveal such systems. These methods have been developed by condensed matter theorists. Furthermore, recently there have been some attempts to apply them to high energy physics. In particular, the tensor renormalization group (TRG) method is remarkable for its applicability to higher dimensions.
The Schwinger model is known as a two-dimensional toy model of QCD. It has the chiral symmetry and theta term in the same way as QCD.

In this study, the free energy of the two-flavor Schwinger model is calculated in a broad range of mass and theta parameters. We use TRG to calculate it, with obvious 2pi periodicity of theta parameter. We check the consistency with analytical values in large and small mass limits.