Chiral Magnetic Effect and Negative Magnetoresistance across the phase diagram of finite-density SU(2) gauge theory

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Main Authors: Buividovich, P. V., von Smekal, L., Smith, D.
Format: Preprint
Published: 2026
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author Buividovich, P. V.
von Smekal, L.
Smith, D.
author_facet Buividovich, P. V.
von Smekal, L.
Smith, D.
contents We study the signatures of the Chiral Magnetic Effect (CME) in $SU(2)$ gauge theory with $N_f = 2$ flavours of dynamical fermions at finite temperature $T$, quark chemical potential $μ$ and a weak external magnetic field $e B$. We consider both the correlator of the axial density and the vector current, which gives direct access to the out-of-equilibrium CME, and the correlator of two vector currents, which probes the CME indirectly via the enhancement of the longitudinal electric conductivity (Negative Magnetoresistance, NMR). We find that the CME response extracted from the vector-axial correlator exhibits a rather weak dependence on temperature and density in the quark-gluon plasma regime, and is very close to the universal value for free massless quarks. The CME is mildly suppressed at low temperatures and large densities in the hadronic phase. In contrast, the NMR behaves in a qualitatively different way across the phase diagram, and is strongly suppressed at either large densities or temperatures. The magnitude of the NMR response appears to be considerably smaller than the prediction based on the lowest Landau level calculation for free quarks. Our findings suggest that for relatively small magnetic field strengths $e B \lesssim m_π^2$ the relation between the CME and NMR might not be as direct as expected. We also do not find statistically significant indications for an enhancement of the CME strength in the vicinity of the crossover or second-order phase transition lines in the $(μ, T)$ phase diagram.
format Preprint
id arxiv_https___arxiv_org_abs_2605_04743
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Chiral Magnetic Effect and Negative Magnetoresistance across the phase diagram of finite-density SU(2) gauge theory
Buividovich, P. V.
von Smekal, L.
Smith, D.
High Energy Physics - Lattice
High Energy Physics - Phenomenology
High Energy Physics - Theory
We study the signatures of the Chiral Magnetic Effect (CME) in $SU(2)$ gauge theory with $N_f = 2$ flavours of dynamical fermions at finite temperature $T$, quark chemical potential $μ$ and a weak external magnetic field $e B$. We consider both the correlator of the axial density and the vector current, which gives direct access to the out-of-equilibrium CME, and the correlator of two vector currents, which probes the CME indirectly via the enhancement of the longitudinal electric conductivity (Negative Magnetoresistance, NMR). We find that the CME response extracted from the vector-axial correlator exhibits a rather weak dependence on temperature and density in the quark-gluon plasma regime, and is very close to the universal value for free massless quarks. The CME is mildly suppressed at low temperatures and large densities in the hadronic phase. In contrast, the NMR behaves in a qualitatively different way across the phase diagram, and is strongly suppressed at either large densities or temperatures. The magnitude of the NMR response appears to be considerably smaller than the prediction based on the lowest Landau level calculation for free quarks. Our findings suggest that for relatively small magnetic field strengths $e B \lesssim m_π^2$ the relation between the CME and NMR might not be as direct as expected. We also do not find statistically significant indications for an enhancement of the CME strength in the vicinity of the crossover or second-order phase transition lines in the $(μ, T)$ phase diagram.
title Chiral Magnetic Effect and Negative Magnetoresistance across the phase diagram of finite-density SU(2) gauge theory
topic High Energy Physics - Lattice
High Energy Physics - Phenomenology
High Energy Physics - Theory
url https://arxiv.org/abs/2605.04743