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. 2007 Dec 7;99(23):231801.
doi: 10.1103/PhysRevLett.99.231801. Epub 2007 Dec 6.

Two-loop effective theory analysis of pi (K)-->enu[over ]_{e}[gamma] branching ratios

Vincenzo Cirigliano  1 , Ignasi Rosell
Affiliations

Two-loop effective theory analysis of pi (K)-->enu[over ]_{e}[gamma] branching ratios

Vincenzo Cirigliano et al. Phys Rev Lett. .

Abstract

We study the ratios R_{e/mu};{(P)} identical withGamma(P-->enu[over ]_{e}[gamma])/Gamma(P-->munu[over ]_{mu}[gamma]) (P=pi, K) in Chiral Perturbation Theory to order e;{2}p;{4}. We complement the two-loop effective theory results with a matching calculation of the counterterm, finding R_{e/mu};{(pi)}=(1.2352+/-0.0001)x10;{-4} and R_{e/mu};{(K)}=(2.477+/-0.001)x10;{-5}.

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