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arXiv · 1908.10765

Magnetic field driven enhancement of the weak decay width of charged pions

M. Coppola·D. Gomez Dumm·S. Noguera·N. N. Scoccola
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Abstract

We study the effect of a uniform magnetic field $\vec B$ on the decays $\pi^-\to l^-\,\bar{\nu}_l$, where $l^-\,=e^-,\,\mu^-$, carrying out a general analysis that includes four $\pi^-$ decay constants. Taking the values of these constants from a chiral effective Nambu-Jona--Lasinio (NJL) model, it is seen that the total decay rate gets strongly increased with respect to the $B=0$ case, with an enhancement factor ranging from $\sim 10$ for $eB=0.1\,\mathrm{GeV}^2$ up to $\sim 10^3$ for $eB=1\,\mathrm{GeV}^2$. The ratio between electronic and muonic decays gets also enhanced, reaching a value of about $1:2$ for $eB=1\,\mathrm{GeV}^2$. In addition, we find that for large $B$ the angular distribution of outgoing antineutrinos shows a significant suppression in the direction of the magnetic field.

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M. Coppola, D. Gomez Dumm, S. Noguera, N. N. Scoccola. 2019-08-28. Magnetic field driven enhancement of the weak decay width of charged pions. https://doi.org/10.1007/jhep09(2020)058

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