The Roberge-Weiss endpoint in N_f = 2 QCD

TL;DR

This paper investigates the critical behavior of the Roberge-Weiss transition endpoint in N_f=2 QCD, confirming its first or second order nature depending on quark mass, and estimates tricritical points.

Contribution

It provides a systematic study of the transition's order in relation to quark mass and estimates tricritical values, extending previous findings.

Findings

Roberge-Weiss endpoint is first order at large/small quark masses.

It is second order at intermediate quark masses.

Tricritical quark mass values are estimated.

Abstract

We present the results of extensive simulations regarding the critical behavior at the endpoint of the Roberge-Weiss transition for N_f = 2 QCD. We confirm early evidence, presented in arXiv:0909.0254, according to which the Roberge-Weiss endpoint is first order in the limit of large or small quark masses, and second order for intermediate masses. A systematic study of the transition strength as a function of the quark mass in the first order regions, permits us to estimate the tricritical values of the quark mass separating the second order region from the first order ones.