Lepton universality test with K+ --> l+ nu decays
Abstract
The NA62 experiment at CERN collected a large sample of K+ e+ decays during a dedicated run in 2007, which allows a precise test of lepton universality by measurement of the helicity suppressed ratio RK = (K+ e+)/(K+μ+). The preliminary result of the analysis of a partial data sample of 51089 K+ e+ candidates is RK=(2.5000.016)×10-5, consistent with the Standard Model expectation.
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