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Measurement of the Absolute Branching Fraction for $Lambda_c^+rightarrow Lambda mu^+ u_{mu}$

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 Added by Lei Li
 Publication date 2016
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and research's language is English




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We report the first measurement of the absolute branching fraction for $Lambda^+_{c}rightarrow Lambda mu^+ u_{mu}$. This measurement is based on a sample of $e^+e^-$ annihilation data at a center-of-mass energy of $sqrt{s}=4.6$ GeV collected with the BESIII detector at the BEPCII storage rings. The sample corresponds to an integrated luminosity of 567 pb$^{-1}$. The branching fraction is determined to be $mathcal B({Lambda^+_crightarrow Lambda mu^+ u_{mu}})=(3.49pm0.46({rm stat})pm0.27({rm syst}))%$. In addition, we calculate the ratio $mathcal{B}(Lambda^+_crightarrow Lambda mu^+ u_{mu})/mathcal{B}(Lambda^+_crightarrow Lambda e^+ u_{e})$ to be $0.96pm0.16({rm stat})pm0.04({rm syst})$.



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122 - M.Ablikim , M.N.Achasov , X.C.Ai 2016
By analyzing 2.93 fb$^{-1}$ of data collected at $sqrt s=3.773$ GeV with the BESIII detector, we measure the absolute branching fraction ${mathcal B}(D^{+}rightarrowbar K^0mu^{+} u_{mu})=(8.72 pm 0.07_{rm stat.} pm 0.18_{rm sys.})%$, which is consistent with previous measurements within uncertainties but with significantly improved precision. Combining the Particle Data Group values of ${mathcal B}(D^0to K^-mu^+ u_mu)$, ${mathcal B}(D^{+}rightarrowbar K^0 e^{+} u_{e})$, and the lifetimes of the $D^0$ and $D^+$ mesons with the value of ${mathcal B}(D^{+}rightarrowbar K^0 mu^{+} u_{mu})$ measured in this work, we determine the following ratios of partial widths: $Gamma(D^0to K^-mu^+ u_mu)/Gamma(D^{+}rightarrowbar K^0mu^{+} u_{mu})=0.963pm0.044$ and $Gamma(D^{+}rightarrowbar K^0 mu^{+} u_{mu})/Gamma(D^{+}rightarrowbar K^0 e^{+} u_{e})=0.988pm0.033$.
337 - M. Ablikim 2021
The absolute branching fraction of $Lambda to p mu^- bar{ u}_{mu}$ is reported for the first time based on an $e^+e^-$ annihilation sample of ten billion $J/psi$ events collected with the BESIII detector at $sqrt{s}=3.097$ GeV. The branching fraction is determined to be ${mathcal B}(Lambda to pmu^- bar{ u}_{mu}) = [1.48pm0.21(rm stat) pm 0.08(rm syst)]times 10^{-4}$, which is a significant improvement in precision over the previous indirect measurements. Combining this result with the world average of ${mathcal B}(Lambda to p e^- bar{ u}_{e})$, we obtain the ratio, $frac{Gamma(Lambda to p mu^- bar{ u}_{mu})}{Gamma(Lambda to p e^- bar{ u}_{e})}$, to be $0.178 pm 0.028$, which agrees with the standard model prediction assuming lepton flavor universality. The asymmetry of the branching fractions of $Lambda to p mu^- bar{ u}_{mu}$ and $bar{Lambda} to bar{p} mu^+ u_{mu}$ is also determined, and no evidence for $CP$ violation is found.
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 $A^{h}_{rm FB} = -0.29 pm 0.07 mbox{ (stat)} pm 0.03 mbox{ (syst)}$.
By analyzing 482 pb$^{-1}$ of $e^+e^-$ collision data collected at the center-of-mass energy $sqrt s=4.009$ GeV with the BESIII detector, we measure the %absolute branching fractions for the semi-leptonic decays $D_{s}^{+}to phi e^{+} u_{e}$, $phi mu^{+} u_{mu}$, $eta mu^{+} u_{mu}$ and $etamu^{+} u_{mu}$ to be ${mathcal B}(D_{s}^{+}tophi e^{+} u_{e})=(2.26pm0.45pm0.09)$%, ${mathcal B}(D_{s}^{+}tophi mu^{+} u_{mu})=(1.94pm0.53pm0.09)$%, ${mathcal B}(D_{s}^{+}toeta mu^{+} u_{mu})=(2.42pm0.46pm0.11)$% and ${mathcal B}(D_{s}^{+}toetamu^{+} u_{mu}) = (1.06pm0.54pm0.07)$%, where the first and second uncertainties are statistical and systematic, respectively. The branching fractions for the three semi-muonic decays $D_s^+tophi mu^+ u_mu, eta mu^+ u_mu$ and $eta mu^+ u_mu$ are determined for the first time and that of $D^+_sto phi e^+ u_e$ is consistent with the world average value within uncertainties.
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.
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