paper

Phase structure of the CP(1) model in the presence of a topological -term

arXiv:2107.14220 · doi:10.1103/PhysRevD.105.054507

Abstract

We numerically study the phase structure of the CP(1) model in the presence of a topological -term, a regime afflicted by the sign problem for conventional lattice Monte Carlo simulations. Using a bond-weighted tensor renormalization group method, we compute the free energy for inverse couplings ranging from and find a CP-violating, first-order phase transition at . In contrast to previous findings, our numerical results provide no evidence for a critical coupling above which a second-order phase transition emerges at and/or the first-order transition line bifurcates at . If such a critical coupling exists, as suggested by Haldane's conjecture, our study indicates that is larger than .

10 pages, 9 figures, v2: updated to match journal version

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