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Register a new userMeasurement of the $B^0 rightarrow K^{*0}e^+e^-$ branching fraction at low dilepton mass
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The branching fraction of the rate decay $B^0 rightarrow K^{*0}e^+e^-$ in the dilepton mass region from 30 to 1000 MeV$/c^2$ has been measured by the LHCb experiment, using $pp$ collision data, corresponding to an integrated luminosity of 1.0 fb$^{-1}$, at a centre-of-mass energy of 7 TeV. The decay mode $B^0 rightarrow J/psi(e^+e^-) K^{*0}$ is utilized as a normalization channel. The branching fraction $B^0 rightarrow K^{*0}e^+e^-$ is measured to be $$ B(B^0 rightarrow K^{*0}e^+e^-)^{30-1000 MeV/c^2}= (3.1, ^{+0.9mbox{} +0.2}_{-0.8mbox{}-0.3} pm 0.2)times 10^{-7}, $$ where the first error is statistical, the second is systematic, and the third comes from the uncertainties on the B^0 rightarrow J/psi K^{*0}$ and $J/psi rightarrow e^+e^- $ branching fractions.
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By analyzing 2.93 fb$^{-1}$ data collected at the center-of-mass energy $sqrt s=3.773$ GeV with the BESIII detector, we measure the absolute branching fraction of the semileptonic decay $D^+rightarrowbar K^0 e^{+} u_{e}$ to be ${mathcal B}(D^{+}rightarrowbar K^0 e^{+} u_{e})=(8.59 pm 0.14 pm 0.21)%$ using $bar K^0to K^0_Sto pi^0pi^0$, where the first uncertainty is statistical and the second systematic. Our result is consistent with previous measurements within uncertainties.
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.
We report on new measurements of Cabibbo-suppressed semileptonic $D_s^+$ decays using $3.19~mathrm{fb}^{-1}$ of $e^+e^-$ annihilation data sample collected at a center-of-mass energy of 4.178~GeV with the BESIII detector at the BEPCII collider. Our results include branching fractions $mathcal B({D^+_srightarrow K^0 e^+ u_{e}})=(3.25pm0.38({rm stat.})pm0.16({rm syst.}))times10^{-3}$ and $mathcal B({D^+_srightarrow K^{*0} e^+ u_{e}})=(2.37pm0.26({rm stat.})pm0.20({rm syst.}))times10^{-3}$ which are much improved relative to previous measurements, and the first measurements of the hadronic form-factor parameters for these decays. For $D^+_srightarrow K^0 e^+ u_{e}$, we obtain $f_+(0)=0.720pm0.084({rm stat.})pm0.013({rm syst.})$, and for $D^+_srightarrow K^{*0} e^+ u_{e}$, we find form-factor ratios $r_V=V(0)/A_1(0)=1.67pm0.34({rm stat.})pm0.16({rm syst.})$ and $r_2=A_2(0)/A_1(0)=0.77pm0.28({rm stat.})pm0.07({rm syst.})$.
A branching fraction measurement of the $B^{0}rightarrow D_{s}^{+}pi^{-}$ decay is presented using proton-proton collision data collected with the LHCb experiment, corresponding to an integrated luminosity of $5.0,$fb$^{-1}$. The branching fraction is found to be ${mathcal{B}(B^{0}rightarrow D_{s}^{+}pi^{-}) = (19.4 pm 1.8pm 1.3 pm 1.2)times 10^{-6}}$, where the first uncertainty is statistical, the second systematic and the third is due to the uncertainty on the $B^0 to D^{-}pi^{+}$, $D_{s}^{+}rightarrow K^{+}K^{-}pi^{+}$ and $D^{-}rightarrow K^{+}pi^{-}pi^{-}$ branching fractions. This is the most precise single measurement of this quantity to date. As this decay proceeds through a single amplitude involving a $b to u$ charged-current transition, the result provides information on non-factorisable strong interaction effects and the magnitude of the Cabibbo-Kobayashi-Maskawa matrix element $V_{ub}$. Additionally, the collision energy dependence of the hadronisation-fraction ratio $f_s/f_d$ is measured through $bar{B}{}_{s}^{0}rightarrow D_{s}^{+}pi^{-}$ and $B^0 to D^{-}pi^{+}$ decays.
We report a measurement of the inclusive semileptonic $B_s^0$ branching fraction in a $121~fb^{-1}$ data sample collected near the $Upsilon(5S)$ resonance with the Belle detector at the KEKB asymmetric energy $e^+ e^-$ collider. Events containing $B_s^0$ pairs are selected by reconstructing a tag side $D_s^+$ and identifying a signal side lepton $ell^+$ ($ell = e, mu$) that is required to have the same-sign charge to ensure that both originate from different $B_s^0$ mesons. The $B_s^0 rightarrow X^- ell^+ u_ell$ branching fraction is extracted from the ratio of the measured yields of $D_s^+$ mesons and $D_s^+ ell^+$ pairs and the known production and branching fractions. The inclusive semileptonic branching fraction is measured to be $[9.6 pm 0.4text{(stat)} pm 0.7text{(syst)}]~%$.
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