0000000001091477
AUTHOR
I. Popov
Test of lepton flavour universality in K+→ℓ+ν decays
Abstract A precision test of lepton flavour universality has been performed by measuring the ratio R K of kaon leptonic decay rates K + → e + ν and K + → μ + ν in a sample of 59 813 reconstructed K + → e + ν candidates with ( 8.71 ± 0.24 ) % background contamination. The result R K = ( 2.487 ± 0.013 ) × 10 − 5 is in agreement with the Standard Model expectation.
Precision measurement of the ratio of the charged kaon leptonic decay rates
A precision measurement of the ratio RK of the rates of kaon leptonic decays K+- --> e nu and K+- --> mu nu with the full data sample collected by the NA62 experiment at CERN in 2007-2008 is reported. The result, obtained by analysing ~150000 reconstructed K+- --> e nu candidates with 11% background contamination, is RK = (2.488+-0.010)*10^{-5}, in agreement with the Standard Model expectation.