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

Abstract

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:

$ \begin{array}{*{20}{c}} {{{{\mathcal{B}\left( {B^0 \to {\pi^{+}}{\pi^{-}}} \right)}} \left/ {{\mathcal{B}\left( {B^0 \to {K^{+}}{\pi^{-}}} \right)}} \right.}=0.262\pm 0.009\pm 0.017,} \\ {\left( {{f_s \left/ {f_d } \right.}} \right)\cdot {{{\mathcal{B}\left( {B_s^0\to {K^{+}}{K^{-}}} \right)}} \left/ {{\mathcal{B}\left( {B^0 \to {K^{+}}{\pi^{-}}} \right)}} \right.}=0.316\pm 0.009\pm 0.019,} \\ {\left( {{f_s \left/ {f_d } \right.}} \right)\cdot {{{\mathcal{B}\left( {B_s^0\to {\pi^{+}}{K^{-}}} \right)}} \left/ {{\mathcal{B}\left( {B^0 \to {K^{+}}{\pi^{-}}} \right)}} \right.}=0.074\pm 0.006\pm 0.006,} \\ {\left( {{f_d \left/ {f_s } \right.}} \right)\cdot {{{\mathcal{B}\left( {B^0 \to {K^{+}}{K^{-}}} \right)}} \left/ {{\mathcal{B}\left( {B_s^0\to {K^{+}}{K^{-}}} \right)}} \right.}=0.018_{-0.007}^{+0.008}\pm 0.009,} \\ {\left( {{f_s \left/ {f_d } \right.}} \right)\cdot {{{\mathcal{B}\left( {B_s^0\to {\pi^{+}}{\pi^{-}}} \right)}} \left/ {{\mathcal{B}\left( {B^0 \to {\pi^{+}}{\pi^{-}}} \right)}} \right.}=0.050_{-0.009}^{+0.011}\pm 0.004,} \\ {{{{\mathcal{B}\left( {\Lambda_b^0\to p{\pi^{-}}} \right)}} \left/ {{\mathcal{B}\left( {\Lambda_b^0\to p{K^{-}}} \right)}} \right.}=0.86\pm 0.08\pm 0.05,} \\ \end{array} $

where the first uncertainties are statistical and the second systematic. Using the current world average of $\mathcal{B}\left( {B^0 \to {K^{+}}{\pi^{-}}} \right)$ and the ratio of the strange to light neutral B meson production f _s /f _d measured by LHCb, we obtain:

$ \begin{array}{*{20}{c}} {\mathcal{B}\left( {B^0 \to {\pi^{+}}{\pi^{-}}} \right)=\left( {5.08\pm 0.17\pm 0.37} \right)\times {10^{-6 }},} \\ {\mathcal{B}\left( {B_s^0\to {K^{+}}{K^{-}}} \right)=\left( {23.0\pm 0.7\pm 2.3} \right)\times {10^{-6 }},} \\ {\mathcal{B}\left( {B_s^0\to {\pi^{+}}{K^{-}}} \right)=\left( {5.4\pm 0.4\pm 0.6} \right)\times {10^{-6 }},} \\ {\mathcal{B}\left( {B^0 \to {K^{+}}{K^{-}}} \right)=\left( {0.11_{-0.04}^{+0.05}\pm 0.06} \right)\times {10^{-6 }},} \\ {\mathcal{B}\left( {B_s^0\to {\pi^{+}}{\pi^{-}}} \right)=\left( {0.95_{-0.17}^{+0.21}\pm 0.13} \right)\times {10^{-6 }}.} \\ \end{array} $

The measurements of $\mathcal{B}\left( {B_s^0\to {K^{+}}{K^{-}}} \right)$, $\mathcal{B}\left( {B_s^0\to {\pi^{+}}{K^{-}}} \right)$ and $\mathcal{B}\left( {B^0 \to {K^{+}}{K^{-}}} \right)$ are the most precise to date. The decay mode $B_s^0\to {\pi^{+}}{\pi^{-}}$ is observed for the first time with a significance of more than 5σ.