Evidence of a CP broken deconfined phase in 4D SU(2) Yang-Mills theory at $θ=π$ from imaginary $θ$ simulations

Fuente: arXiv
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Main Authors: Hirasawa, Mitsuaki, Honda, Masazumi, Matsumoto, Akira, Nishimura, Jun, Yosprakob, Atis
Format: Preprint
Published: 2024
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author Hirasawa, Mitsuaki
Honda, Masazumi
Matsumoto, Akira
Nishimura, Jun
Yosprakob, Atis
author_facet Hirasawa, Mitsuaki
Honda, Masazumi
Matsumoto, Akira
Nishimura, Jun
Yosprakob, Atis
contents The spontaneous breaking of CP symmetry in 4D SU($N$) pure Yang-Mills theory at $θ=π$ has recently attracted much attention in the context of the higher-form symmetry and the 't Hooft anomaly matching condition. Here we use Monte Carlo simulations to study the $N=2$ case, which is interesting since it is the case opposite to the large-$N$ limit, where explicit calculations are available. In order to circumvent the severe sign problem due to the $θ$ term for real $θ$, we first obtain results at imaginary $θ$, where the sign problem is absent, and make an analytic continuation to real $θ$. We use the stout smearing in defining the $θ$ term in the action to be used in our simulations. Thus we obtain the expectation value of the topological charge and the deconfining temperature at $θ=π$, and provide an evidence that the CP symmetry, which is spontaneously broken at low temperature, gets restored \emph{strictly above} the deconfining temperature. This conclusion is consistent with the anomaly matching condition and yet differs from the prediction in the large-$N$ limit.
format Preprint
id arxiv_https___arxiv_org_abs_2412_03683
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle Evidence of a CP broken deconfined phase in 4D SU(2) Yang-Mills theory at $θ=π$ from imaginary $θ$ simulations
Hirasawa, Mitsuaki
Honda, Masazumi
Matsumoto, Akira
Nishimura, Jun
Yosprakob, Atis
High Energy Physics - Theory
High Energy Physics - Lattice
High Energy Physics - Phenomenology
The spontaneous breaking of CP symmetry in 4D SU($N$) pure Yang-Mills theory at $θ=π$ has recently attracted much attention in the context of the higher-form symmetry and the 't Hooft anomaly matching condition. Here we use Monte Carlo simulations to study the $N=2$ case, which is interesting since it is the case opposite to the large-$N$ limit, where explicit calculations are available. In order to circumvent the severe sign problem due to the $θ$ term for real $θ$, we first obtain results at imaginary $θ$, where the sign problem is absent, and make an analytic continuation to real $θ$. We use the stout smearing in defining the $θ$ term in the action to be used in our simulations. Thus we obtain the expectation value of the topological charge and the deconfining temperature at $θ=π$, and provide an evidence that the CP symmetry, which is spontaneously broken at low temperature, gets restored \emph{strictly above} the deconfining temperature. This conclusion is consistent with the anomaly matching condition and yet differs from the prediction in the large-$N$ limit.
title Evidence of a CP broken deconfined phase in 4D SU(2) Yang-Mills theory at $θ=π$ from imaginary $θ$ simulations
topic High Energy Physics - Theory
High Energy Physics - Lattice
High Energy Physics - Phenomenology
url https://arxiv.org/abs/2412.03683