Measurement of the absolute branching ratios for semileptonic K+/- decays with the KLOE detector

Using a sample of over 600 million phi --> K+ K- decays collected at the DA Phi NE e(+)e(-) collider, we have measured with the KLOE detector the absolute branching ratios for the charged kaon semileptonic decays, K+/- --> pi(0)e(+/-)nu(gamma) and K+/- --> pi(0)mu(+/-)nu(gamma). The results, BR(K-e3) = 0.04965 +/- 0.00038(stat) +/- 0.00037(syst) and BR(K-mu 3) = 0.03233 +/- 0.00029(stat) +/- 0.00026(syst), are inclusive of radiation. Accounting for correlations, we derive the ratio Gamma(K-mu 3)/Gamma(K-e3) = 0.6511 +/- 0.0064. Using the semileptonic form factors measured in the same experiment, we obtain vertical bar V-us f(+)(0)vertical bar = 0.2141 +/- 0.0013.