The lifetime of unstable particles in electromagnetic fields

Abstract

We show that the electromagnetic moments of unstable particles (resonances) have an absorptive contribution which quantifies the change of the particle's lifetime in an external electromagnetic field. To give an example we compute here the imaginary part of the magnetic moment for the cases of the muon and the neutron at leading order in the electroweak coupling. We also consider an analogous effect for the strongly-decaying $\Delta$(1232) resonance. The result for the muon is Im$\mu =e{G}_F^2{m}^3/768{\pi }^3$, with $e$ the charge and $m$ the mass of the muon, $G_F$ the Fermi constant, which in an external magnetic field of $B$ Tesla give rise to the relative change in the muon lifetime of $3\times 10^{-15}B$. For neutron the effect is of a similar magnitude. We speculate on the observable implications of this effect.

11 pages, 3 figs; published version

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Cited by in corpus (3)

• A fake doublet solution to the muon anomalous magnetic moment
• The Delta(1232) Resonance in Chiral Effective Field Theory
• Bounds on Lorentz-violating Yukawa couplings via lepton electromagnetic moments