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Register a new userMeasurement of absolute branching fraction of the inclusive decay $Lambda_{c}^{+} to Lambda + X$
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Based on an $e^+e^-$ collision data sample corresponding to an integrated luminosity of 567$,rm{pb}^{-1}$ taken at the center-of-mass energy of $sqrt{s} = 4.6$ GeV with the BESIII detector, we measure the absolute branching fraction of the inclusive decay $Lambda_{c}^{+} to Lambda + X$ to be $mathcal{B}(Lambda_{c}^{+} to Lambda + X)=(38.2^{+2.8}_{-2.2}pm0.8)%$ using the double-tag method, where $X$ refers to any possible final state particles. In addition, we search for direct CP violation in the charge asymmetry of this inclusive decay for the first time, and obtain $mathcal{A}_{CP} equiv frac{mathcal{B}(Lambda_{c}^{+} to Lambda + X)-mathcal{B}(bar{Lambda}_{c}^{-} to bar{Lambda} + X)}{mathcal{B}(Lambda_{c}^{+} to Lambda + X)+mathcal{B}(bar{Lambda}_{c}^{-} to bar{Lambda} + X)} = (2.1^{+7.0}_{-6.6}pm1.4)%$, a statistically limited result with no evidence of CP violation.
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We report the first absolute measurement of the branching fraction of $Lambda^+_{c}rightarrow Lambda e^+ u_e$. This measurement is based on 567 pb$^{-1}$ of $e^+e^-$ annihilation data produced at $sqrt{s}=4.599$ GeV, which is just above the $Lambda^+_cbar{Lambda}^-_c$ threshold. The data were collected with the BESIII detector at the BEPCII storage rings. The branching fraction is determined to be $mathcal B({Lambda^+_crightarrow Lambda e^+ u_e})=(3.63pm0.38({rm stat})pm0.20({rm syst}))%$, representing a more than twofold improvement in precision upon previously published results. As the branching fraction for $Lambda^+_{c}rightarrow Lambda e^+ u_e$ is the benchmark for those of other $Lambda^+_c$ semileptonic channels, our result provides a unique test of different theoretical models, which is the most stringent to date.
Using a data sample corresponding to an integrated luminosity of 567 pb$^{-1}$ collected at a center-of-mass energy of $sqrt{s}=4.6$ GeV with the BESIII detector, we measure the absolute branching fraction of the inclusive semileptonic $Lambda_c^+$ decay with a double-tag method. We obtain $mathcal{B}(Lambda_c^+ rightarrow X e^+ u_e) = (3.95pm0.34pm0.09)%$, where the first uncertainty is statistical and the second systematic. Using the known $Lambda_c^+$ lifetime and the charge-averaged semileptonic decay width of nonstrange charmed measons ($D^0$ and $D^+$), we obtain the ratio of the inclusive semileptonic decay widths $Gamma(Lambda_c^+ rightarrow X e^+ u_e)/bar{Gamma}(Drightarrow X e^+ u_e)= 1.26pm0.12$.
We report the first measurement of the absolute branching fraction of the inclusive decay $Lambda_c^+ to K_S^0X$. The analysis is performed using an $e^+e^-$ collision data sample corresponding to an integrated luminosity of 567 pb$^{-1}$ taken at $sqrt{s}$ = 4.6 GeV with the BESIII detector. Using eleven Cabibbo-favored $bar{Lambda}_c^-$ decay modes and the double-tag technique, this absolute branching fraction is measured to be $mathcal{B}(Lambda_c^+ to K_S^0X)=(9.9pm0.6pm0.4)%$, where the first uncertainty is statistical and the second systematic. The relative deviation between the branching fractions for the inclusive decay and the observed exclusive decays is $(18.7pm8.3)%$, which indicates that there may be some unobserved decay modes with a neutron or excited baryons in the final state.
We measure the inclusive semielectronic decay branching fraction of the $D_s^+$ meson. A double-tag technique is applied to $e^+e^-$ annihilation data collected by the BESIII experiment at the BEPCII collider, operating in the center-of-mass energy range $4.178 - 4.230$ GeV. We select positrons from $D_s^+rightarrow Xe^{+} u_e$ with momenta greater than 200 MeV/$c$, and determine the laboratory momentum spectrum, accounting for the effects of detector efficiency and resolution. The total positron yield and semielectronic branching fraction are determined by extrapolating this spectrum below the momentum cutoff. We measure the $D_s^+$ semielectronic branching fraction to be $mathcal{B}left(D_s^+rightarrow Xe^{+} u_eright)=left(6.30pm0.13;(text{stat.})pm 0.10;(text{syst.})right)%$, showing no evidence for unobserved exclusive semielectronic modes. We combine this result with external data taken from literature to determine the ratio of the $D_s^+$ and $D^0$ semielectronic widths, $frac{Gamma(D_{s}^{+}rightarrow Xe^+ u_e)}{Gamma(D^0rightarrow Xe^+ u_e)}=0.790pm 0.016;(text{stat.})pm0.020;(text{syst.})$. Our results are consistent with and more precise than previous measurements.
Inclusive semileptonic B_s^0 -> X^+ l^- u decays are studied for the first time using a 23.6 fb^{-1} data sample collected on the Y(5S) resonance with the Belle detector at the KEKB asymmetric energy e^+ e^- collider. These decays are identified by the means of a lepton accompanied by a same-sign D_s^+ meson originating from the other B_s^0 in the event. The semileptonic branching fractions are measured in the electron and muon channels to be Bf(B_s^0 -> X^+ e^- u) = (10.9 pm 1.0 pm 0.9)% and Bf(B_s^0 -> X^+ mu^- u) = (9.2 pm 1.0 pm 0.8)%, respectively. Assuming an equal electron and muon production rate in B_s^0 decays, a combined fit yields an average leptonic branching fraction Bf(B_s^0 -> X^+ l^- u) = (10.2 pm 0.8 pm 0.9)%.
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