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Register a new userMeasurements of the S-wave fraction in $B^{0}rightarrow K^{+}pi^{-}mu^{+}mu^{-}$ decays and the $B^{0}rightarrow K^{ast}(892)^{0}mu^{+}mu^{-}$ differential branching fraction
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A measurement of the differential branching fraction of the decay ${B^{0}rightarrow K^{ast}(892)^{0}mu^{+}mu^{-}}$ is presented together with a determination of the S-wave fraction of the $K^+pi^-$ system in the decay $B^{0}rightarrow K^{+}pi^{-}mu^{+}mu^{-}$. The analysis is based on $pp$-collision data corresponding to an integrated luminosity of 3,fb$^{-1}$ collected with the LHCb experiment. The measurements are made in bins of the invariant mass squared of the dimuon system, $q^2$. Precise theoretical predictions for the differential branching fraction of $B^{0}rightarrow K^{ast}(892)^{0}mu^{+}mu^{-}$ decays are available for the $q^2$ region $1.1<q^2<6.0,{rm GeV}^2/c^4$. In this $q^2$ region, for the $K^+pi^-$ invariant mass range $796 < m_{Kpi} < 996,{rm MeV}/c^2$, the S-wave fraction of the $K^+pi^-$ system in $B^{0}rightarrow K^{+}pi^{-}mu^{+}mu^{-}$ decays is found to be begin{equation*} F_{rm S} = 0.101pm0.017({rm stat})pm0.009 ({rm syst}), end{equation*} and the differential branching fraction of $B^{0}rightarrow K^{ast}(892)^{0}mu^{+}mu^{-}$ decays is determined to be begin{equation*} {rm d}mathcal{B}/{rm d} q^2 = (0.342_{,-0.017}^{,+0.017}({rm stat})pm{0.009}({rm syst})pm0.023({rm norm}))times 10^{-7}c^{4}/{rm GeV}^{2}. end{equation*} The differential branching fraction measurements presented are the most precise to date and are found to be in agreement with Standard Model predictions.
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The direct $C!P$ asymmetries of the decays $B^0 rightarrow K^{*0} mu^+ mu^-$ and $B^+ rightarrow K^{+} mu^+ mu^-$ are measured using $pp$ collision data corresponding to an integrated luminosity of 3.0$mbox{fb}^{-1}$ collected with the LHCb detector. The respective control modes $B^0 rightarrow J/psi K^{*0}$ and $B^+ rightarrow J/psi K^{+}$ are used to account for detection and production asymmetries. The measurements are made in several intervals of $mu^+ mu^-$ invariant mass squared, with the $phi(1020)$ and charmonium resonance regions excluded. Under the hypothesis of zero $C!P$ asymmetry in the control modes, the average values of the asymmetries are begin{align} {cal A}_{C!P}(B^0 rightarrow K^{*0} mu^+ mu^-) &= -0.035 pm 0.024 pm 0.003, cr {cal A}_{C!P}(B^+ rightarrow K^{+} mu^+ mu^-) &= phantom{-}0.012 pm 0.017 pm 0.001, end{align} where the first uncertainties are statistical and the second are due to systematic effects. Both measurements are consistent with the Standard Model prediction of small $C!P$ asymmetry in these decays.
The differential branching fraction of the rare decay $Lambda^{0}_{b} rightarrow Lambda mu^+mu^-$ is measured as a function of $q^{2}$, the square of the dimuon invariant mass. The analysis is performed using proton-proton collision data, corresponding to an integrated luminosity of $3.0 mbox{ fb}^{-1}$, collected by the LHCb experiment. Evidence of signal is observed in the $q^2$ region below the square of the $J/psi$ mass. Integrating over $15 < q^{2} < 20 mbox{ GeV}^2/c^4$ the branching fraction is measured as $dmathcal{B}(Lambda^{0}_{b} rightarrow Lambda mu^+mu^-)/dq^2 = (1.18 ^{+ 0.09} _{-0.08} pm 0.03 pm 0.27) times 10^{-7} ( mbox{GeV}^{2}/c^{4})^{-1}$, where the uncertainties are statistical, systematic and due to the normalisation mode, $Lambda^{0}_{b} rightarrow J/psi Lambda$, respectively. In the $q^2$ intervals where the signal is observed, angular distributions are studied and the forward-backward asymmetries in the dimuon ($A^{l}_{rm FB}$) and hadron ($A^{h}_{rm FB}$) systems are measured for the first time. In the range $15 < q^2 < 20 mbox{ GeV}^2/c^4$ they are found to be $A^{l}_{rm FB} = -0.05 pm 0.09 mbox{ (stat)} pm 0.03 mbox{ (syst)}$ and $A^{h}_{rm FB} = -0.29 pm 0.07 mbox{ (stat)} pm 0.03 mbox{ (syst)}$.
The angular distribution and differential branching fraction of the decay $B^{0} to K^{*0} mu^{+}mu^{-}$ are studied using a data sample, collected by the LHCb experiment in $pp$ collisions at $sqrt{s}=7,{rm TeV}$, corresponding to an integrated luminosity of $1.0,{rm fb}^{-1}$. Several angular observables are measured in bins of the dimuon invariant mass squared, $q^{2}$. A first measurement of the zero-crossing point of the forward-backward asymmetry of the dimuon system is also presented. The zero-crossing point is measured to be $q_{0}^{2} = 4.9 pm 0.9 ,{rm GeV}^{2}/c^{4}$, where the uncertainty is the sum of statistical and systematic uncertainties. The results are consistent with the Standard Model predictions.
The angular distribution and differential branching fraction of the decay $B^{+} rightarrow K^{+}mu^{+}mu^{-}$ are studied with a dataset corresponding to $1.0,mathrm{fb}^{-1}$ of integrated luminosity, collected by the LHCb experiment. The angular distribution is measured in bins of dimuon invariant mass squared and found to be consistent with Standard Model expectations. Integrating the differential branching fraction over the full dimuon invariant mass range yields a total branching fraction of $mathcal{B}(B^{+} rightarrow K^{+}mu^{+}mu^{-}) = (4.36 pm 0.15 pm 0.18)times 10^{-7}$. These measurements are the most precise to date of the $B^{+} rightarrow K^{+}mu^{+}mu^{-}$ decay.
Measurements of the differential branching fraction and angular moments of the decay $B^0 to K^+ pi^- mu^+ mu^-$ in the $K^+pi^-$ invariant mass range $1330<m(K^+ pi^-)<1530~MeV/c^2$ are presented. Proton-proton collision data are used, corresponding to an integrated luminosity of 3 $fb^{-1}$ collected by the LHCb experiment. Differential branching fraction measurements are reported in five bins of the invariant mass squared of the dimuon system, $q^2$, between 0.1 and 8.0 $GeV^2/c^4$. For the first time, an angular analysis sensitive to the S-, P- and D-wave contributions of this rare decay is performed. The set of 40 normalised angular moments describing the decay is presented for the $q^2$ range 1.1--6.0 $GeV^2/c^4$.
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