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Register a new userMeasurement of the differential branching fraction of the decay $Lambda_b^0rightarrowLambdamu^+mu^-$
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The differential branching fraction of the decay $Lambda_b^0rightarrowLambdamu^+mu^-$ is measured as a function of the square of the dimuon invariant mass, $q^2$. A yield of $78pm12$ $Lambda_b^0rightarrowLambdamu^+mu^-$ decays is observed using data, corresponding to an integrated luminosity of 1.0,fb$^{-1}$, collected by the LHCb experiment at a centre-of-mass energy of 7,TeV. A significant signal is found in the $q^2$ region above the square of the $J/psi$ mass, while at lower-$q^2$ values upper limits are set on the differential branching fraction. Integrating the differential branching fraction over $q^2$, while excluding the $J/psi$ and $psi(2S)$ regions, gives a branching fraction of $BF($Lambda_b^0rightarrowLambdamu^+mu^-$)=(0.96pm 0.16statpm 0.13systpm 0.21 (mathrm{norm}))times 10^{-6}$, where the uncertainties are statistical, systematic and due to the normalisation mode, $$Lambda_b^0rightarrow J/psiLambda$, respectively.
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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.
The determination of the differential branching fraction and the first angular analysis of the decay $B_s^0tophimu^{+}mu^{-}$ are presented using data, corresponding to an integrated luminosity of $1.0,{rm fb}^{-1}$, collected by the LHCb experiment at $sqrt{s}=7,{rm TeV}$. The differential branching fraction is determined in bins of $q^{2}$, the invariant dimuon mass squared. Integration over the full $q^{2}$ range yields a total branching fraction of ${cal B}(B_s^0tophimu^{+}mu^{-}) = (7.07,^{+0.64}_{-0.59}pm 0.17 pm 0.71)times 10^{-7}$, where the first uncertainty is statistical, the second systematic, and the third originates from the branching fraction of the normalisation channel. An angular analysis is performed to determine the angular observables $F_{rm L}$, $S_3$, $A_6$, and $A_9$. The observables are consistent with Standard Model expectations.
An angular analysis and a measurement of the differential branching fraction of the decay $B^0_stophimu^+mu^-$ are presented, using data corresponding to an integrated luminosity of $3.0, {rm fb^{-1}}$ of $pp$ collisions recorded by the LHCb experiment at $sqrt{s} = 7$ and $8, {rm TeV}$. Measurements are reported as a function of $q^{2}$, the square of the dimuon invariant mass and results of the angular analysis are found to be consistent with the Standard Model. In the range $1<q^2<6, {rm GeV}^{2}/c^{4}$, where precise theoretical calculations are available, the differential branching fraction is found to be more than $3,sigma$ below the Standard Model predictions.
The differential branching fraction with respect to the dimuon invariant mass squared, and the $C!P$ asymmetry of the $B^pmtopi^pmmu^+mu^-$ decay are measured for the first time. The CKM matrix elements $|V_{td}|$ and $|V_{ts}|$, and the ratio $|V_{td}/V_{ts}|$ are determined. The analysis is performed using proton-proton collision data corresponding to an integrated luminosity of 3.0 fb$^{-1}$, collected by the LHCb experiment at centre-of-mass energies of 7 and 8 TeV. The total branching fraction and $C!P$ asymmetry of $B^pmtopi^pmmu^+mu^-$ decays are measured to be begin{eqnarray} mathcal{B}(B^pmtopi^pmmu^+mu^-) &=& (1.83 pm 0.24 pm 0.05) times 10^{-8},,,mathrm{and} onumber mathcal{A}_{C!P}(B^pmtopi^pmmu^+mu^-) &=& -0.11 pm 0.12 pm 0.01,, onumber end{eqnarray} where the first uncertainties are statistical and the second are systematic. These are the most precise measurements of these observables to date, and they are compatible with the predictions of the Standard Model.
A measurement of the shape of the differential decay rate and the associated Isgur-Wise function for the decay $Lambda_b^0toLambda_c^+mu^-overline{ u}$ is reported, using data corresponding to $3 fb^{-1}$ collected with the LHCb detector in proton-proton collisions. The $Lambda_c^+mu^-overline{ u}$(+ anything) final states are reconstructed through the detection of a muon and a $Lambda_c^+$ baryon decaying into $pK^-pi^+$, and the decays $Lambda_b^0toLambda_c^+pi^+pi^-mu^-overline{ u}$ are used to determine contributions from $Lambda_b^0to Lambda_c^{star+}mu ^-bar{ u}$ decays. The measured dependence of the differential decay rate upon the squared four-momentum transfer between the heavy baryons, $q^2$, is compared with expectations from heavy-quark effective theory and from unquenched lattice QCD predictions.
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