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# 36th Annual International Symposium on Lattice Field Theory

22-28 July 2018
Kellogg Hotel and Conference Center
EST timezone

## The critical endpoint in the 2-d U(1) gauge-Higgs model at topological angle $\theta=\pi$

Jul 25, 2018, 2:40 PM
20m
Centennial (Kellogg Hotel and Conference Center)

### Centennial

#### Kellogg Hotel and Conference Center

219 S Harrison Rd, East Lansing, MI 48824
Theoretical Developments

### Speaker

Mr Daniel Goeschl (University of Graz)

### Description

We investigate the phase structure of the 2-d U(1) gauge-Higgs model at non-vanishing topological angle $\theta$. The sign problem arising from the topological term is avoided by invoking a dual representation of the gauge-Higgs model. This allows us to observe a 1st order transition in the topological charge at the symmetrical point $\theta=\pi$. By using the Villain action to discretize the gauge field dynamics, we implement the corresponding symmetry as an exact $Z_2$ symmetry of the dual variables. We perform simulations to determine the critical endpoint of this transition as a function of the mass parameter and, using FSS techniques, show that it falls into the universality class of the 2-d Ising model.

### Primary author

Mr Daniel Goeschl (University of Graz)

### Co-authors

Prof. Christof Gattringer (University of Graz) Dr Sulejmanpasic Tin (ENS Paris)

 Slides