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arXiv · 1509.06222

Electromagnetic triangle anomaly and neutral pion condensation in QCD vacuum

Gaoqing Cao·Xu-Guang Huang
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Abstract

We study the QCD vacuum structure under the influence of an electromagnetic field with a nonzero second Lorentz invariant $I_2=\vec{E}\cdot{\vec B}$. We show that the presence of $I_2$ can induce neutral pion ($π^0$) condensation in the QCD vacuum through the electromagnetic triangle anomaly. Within the frameworks of chiral perturbation theory at leading small-momenta expansion as well as the Nambu--Jona-Lasinio model at leading $1/N_c$ expansion, we quantify the dependence of the $π^0$ condensate on $I_2$. The stability of the $π^0$-condensed vacuum against the Schwinger charged pair production due to electric field is also discussed.

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Gaoqing Cao, Xu-Guang Huang. 2016-04-07. Electromagnetic triangle anomaly and neutral pion condensation in QCD vacuum. https://doi.org/10.1016/j.physletb.2016.03.066

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