Flavor violating leptonic decays of τ and μ leptons in the Standard Model with massive neutrinos
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Springer Nature
Fecha
2019Referencia bibliográfica
Hernández-Tomé, G., Castro, G. L., & Roig, P. (2019). Flavor violating leptonic decays of τ and μ leptons in the Standard Model with massive neutrinos. The European Physical Journal C, 79(1), 84.
Patrocinador
Finally, we also acknowledge support from Conacyt through projects FOINS-296-2016 (Fronteras de la Ciencia), and 236394 and 250628 (Ciencia Básica).Resumen
We have revisited the computations of the flavor
violating leptonic decays of the τ and μ leptons into three
lighter charged leptons in the Standard Model with massive
neutrinos. We were driven by a claimed unnaturally large
branching ratio predicted for the τ
− → μ
−
l
+
l
− (l = μ, e)
decays (Pham, Eur Phys J C 8:513 1999), which was at odds
with the corresponding predictions for the μ
− → e−e−e+
processes (Petcov, Sov J Nucl Phys 25:340 1977). In contrast
with the prediction in [17], our results are strongly suppressed
and in good agreement with the approximationmade
in Ref. [15], where masses and momenta of the external particles
were neglected in order to deal with the loop integrals.
However -as a result of keeping external momenta and
masses in the computation of the dominant penguin and box
diagrams- we even find slightly smaller branching fractions.
Therefore, we confirm that any future observation of such
processes would be an unambiguous manifestation of new
physics beyond the Standard Model.