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arXiv · 1711.06537

First lattice calculation of the QED corrections to leptonic decay rates

D. Giusti·V. Lubicz·G. Martinelli·C. T. Sachrajda·F. Sanfilippo·S. Simula·N. Tantalo·C. Tarantino
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Abstract

The leading-order electromagnetic and strong isospin-breaking corrections to the ratio of $K_{\mu 2}$ and $\pi_{\mu 2}$ decay rates are evaluated for the first time on the lattice, following a method recently proposed. The lattice results are obtained using the gauge ensembles produced by the European Twisted Mass Collaboration with $N_f = 2 + 1 + 1$ dynamical quarks. Systematics effects are evaluated and the impact of the quenched QED approximation is estimated. Our result for the correction to the tree-level $K_{\mu 2} / \pi_{\mu 2}$ decay ratio is $-1.22\,(16) \%$ to be compared to the estimate $-1.12\,(21) \%$ based on Chiral Perturbation Theory and adopted by the Particle Data Group.

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D. Giusti, V. Lubicz, G. Martinelli, C. T. Sachrajda, F. Sanfilippo, S. Simula, N. Tantalo, C. Tarantino. 2017-11-17. First lattice calculation of the QED corrections to leptonic decay rates. https://doi.org/10.1103/physrevlett.120.072001

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