The gradient flow equation in the 2D O(N) nonlinear sigma model with lattice regularization is solved in the leading order of the 1/N expansion. By using this solution, we analytically compute the thermal expectation value of a lattice energy-momentum tensor defined through the gradient flow. The expectation value reproduces thermodynamic quantities obtained by the standard large-N method. This analysis confirms that the above lattice energy-momentum tensor restores the correct normalization automatically in the continuum limit, in a system with a nonperturbative mass gap.
All Science Journal Classification (ASJC) codes
- Physics and Astronomy(all)