Measurement of the effective $B_s^0\to K^{+}{K}^{-}$ lifetime

A precise determination of the effective $B_s^0\to K^{+}{K}^{-}$ lifetime can be used to constrain contributions from physics beyond the Standard Model in the $B_s^0$ meson system. Conventional approaches select $B$ meson decay products that are significantly displaced from the $B$ meson production vertex. As a consequence, $B$ mesons with low decay times are suppressed, introducing a bias to the decay time spectrum which must be corrected. This analysis uses a technique that explicitly avoids a lifetime bias by using a neural network based trigger and event selection. Using 1.0 fb${}^{-1}$ of data recorded by the LHCb experiment, the effective $B_s^0\to K^{+}{K}^{-}$ lifetime is measured as $1.455 \pm 0.046 ; $(\mathrm{s}\mathrm{t}\mathrm{a}\mathrm{t}\mathrm{.})$ \pm 0.006 ; $(\mathrm{s}\mathrm{y}\mathrm{s}\mathrm{t}\mathrm{.})$ , $\mathrm{p}\mathrm{s}$.$