The ratio of the K+→π0μ+ν (Kμ3+​) and K+→π0e+ν (Ke3+​) decay widths, Γ(Kμ3​)/Γ(Ke3​), has been measured with stopped positive kaons.
Kμ3+​ and Ke3+​ samples containing 2.4×104 and 4.0×104 events, respectively, were analyzed. The
Γ(Kμ3​)/Γ(Ke3​) ratio was obtained to be
0.671±0.007(stat.)±0.008(syst.) calculating the detector acceptance by
a Monte Carlo simulation with the assumption of μ-e universality in
Kl3+​ decay. The coefficient of the q2 dependent term of the f0​ form
factor was also determined to be
λ0​=0.022±0.005(stat.)±0.004(syst.).Comment: 12 pages, 6 figure