Measurement of b -hadron branching fractions for two-body decays into charmless charged hadrons

Based on data corresponding to an integrated luminosity of 0.37 fb −1 collected by the LHCb experiment in 2011, the following ratios of branching fractions are measured: [ ℬ( B^0 →π^+π^-)/ ℬ( B^0 →K^+π^-).=0.262± 0.009± 0.017,; ( f_s / f_d .)·ℬ( B_s^0→K^+K^-)/ ℬ( B^0 →K^+π^-).=0.316± 0.009± 0.019,; ( f_s / f_d .)·ℬ( B_s^0→π^+K^-)/ ℬ( B^0 →K^+π^-).=0.074± 0.006± 0.006,; ( f_d / f_s .)·ℬ( B^0 →K^+K^-)/ ℬ( B_s^0→K^+K^-).=0.018_-0.007^+0.008± 0.009,; ( f_s / f_d .)·ℬ( B_s^0→π^+π^-)/ ℬ( B^0 →π^+π^-).=0.050_-0.009^+0.011± 0.004,; ℬ( Λ_b^0→ pπ^-)/ ℬ( Λ_b^0→ pK^-).=0.86± 0.08± 0.05,; ] where the first uncertainties are statistical and the second systematic. Using the current world average of ℬ( B^0 →K^+π^-) and the ratio of the strange to light neutral B meson production f s / f d measured by LHCb, we obtain: [ ℬ( B^0 →π^+π^-)=( 5.08± 0.17± 0.37)×10^-6 ,; ℬ( B_s^0→K^+K^-)=( 23.0± 0.7± 2.3)×10^-6 ,; ℬ( B_s^0→π^+K^-)=( 5.4± 0.4± 0.6)×10^-6 ,; ℬ( B^0 →K^+K^-)=( 0.11_-0.04^+0.05± 0.06)×10^-6 ,; ℬ( B_s^0→π^+π^-)=( 0.95_-0.17^+0.21± 0.13)×10^-6 .; ] The measurements of ℬ( B_s^0→K^+K^-) , ℬ( B_s^0→π^+K^-) and ℬ( B^0 →K^+K^-) are the most precise to date. The decay mode B_s^0→π^+π^- is observed for the first time with a significance of more than 5 σ .