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arXiv · 1504.06349

Axial anomaly effects in finite isospin $χ$PT in a magnetic field

Prabal Adhikari
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Abstract

In this paper, we consider finite isospin chiral perturbation theory including the effects of the axial anomaly (through the Wess-Zumino-Witten term) in a strong magnetic field. We firstly prove that in a strong external magnetic field ($H_{\rm ext}$) or more precisely the Schwinger limit, where photon back-reactions are suppressed, only neutral pions can condense and the condensation of charged pions is forbidden. Secondly, we find that the $π^{0}$ domain wall is an example of a phase that can exist in a strong magnetic field and suggest the existence of a new phase transition line from the normal vacuum state to the $π^{0}$ domain wall state. This phase transition exists for non-zero pion masses if the baryon chemical potential exceeds a critical value $16πf_π^{2}m_π/eH_{\rm ext}$. The phase transition line persists away from the Schwinger limit when the photons can back-react to the external magnetic field.

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Prabal Adhikari. 2015-04-23. Axial anomaly effects in finite isospin $χ$PT in a magnetic field. https://arxiv.org/abs/1504.06349

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