Two-loop electroweak corrections for theK→πνν¯decays

Joachim Brod, Martin Gorbahn, Emmanuel Stamou
2011 Physical Review D  
The rare K -> pi nu anti-nu decays play a central role in testing the Standard Model and its extensions. Upcoming experiments plan to measure the decay rates with high accuracy. Yet, unknown higher-order electroweak corrections result in a sizeable theory error. We remove this uncertainty by computing the full two-loop electroweak corrections to the top-quark contribution X_t to the rare decays K_L -> pi0 nu anti-nu, K+ -> pi+ nu anti-nu, and B -> X_d,s nu anti-nu in the Standard Model. The
more » ... dard Model. The remaining theoretical uncertainty related to electroweak effects is now far below 1 Finally we update the branching ratios to find Br(K_L -> pi0 nu anti-nu) = 2.43(39)(6) * 10^-11 and Br(K+ -> pi+ nu anti-nu) = 7.81(75)(29) * 10^-11. The first error summarises the parametric, the second the remaining theoretical uncertainties.
doi:10.1103/physrevd.83.034030 fatcat:vvlf4y5mznadro3h7j2c7gvkia