اشترك بالحزمة الذهبية واحصل على وصول غير محدود شمرا أكاديميا
تسجيل مستخدم جديدAbsolute Measurement of Hadronic Branching Fractions of the D_s^+ Meson
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The branching fractions of D_s meson decays serve to normalize many measurements of processes involving charm quarks. Using 298 /pb of e+ e- collisions recorded at a center of mass energy of 4.17 GeV, we determine absolute branching fractions for eight D_s decays with a double tag technique. In particular we determine the branching fraction B(D_s -> K- K+ pi+) = (5.50 +- 0.23 +- 0.16)%, where the uncertainties are statistical and systematic respectively. We also provide partial branching fractions for kinematic subsets of the K- K+ pi+ decay mode.
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The branching fractions of Ds meson decays serve to normalize many measurements of processes involving charm quarks. Using 586 pb^-1 of e+ e- collisions recorded at a center of mass energy of 4.17 GeV, we determine absolute branching fractions for 13
Ds decays in 16 reconstructed final states with a double tag technique. In particular we make a precise measurement of the branching fraction B(Ds -> K- K+ pi+) = (5.55 +- 0.14 +- 0.13)%, where the uncertainties are statistical and systematic respectively. We find a significantly reduced value of B(Ds -> pi+ pi0 eta) compared to the world average, and our results bring the inclusively and exclusively measured values of B(Ds -> eta X)$ into agreement. We also search for CP-violating asymmetries in Ds decays and measure the cross-section of e+ e- -> Ds* Ds at Ecm = 4.17 GeV.
We report new measurements of the branching fraction $cal B(D_s^+to ell^+ u)$, where $ell^+$ is either $mu^+$ or $tau^+(topi^+bar{ u}_tau)$, based on $6.32$ fb$^{-1}$ of electron-positron annihilation data collected by the BESIII experiment at six ce
nter-of-mass energy points between $4.178$ GeV and $4.226$ GeV. Simultaneously floating the $D_s^+tomu^+ u_mu$ and $D_s^+totau^+ u_tau$ components yields $cal B(D_s^+to tau^+ u_tau) = (5.21pm0.25pm0.17)times10^{-2}$, $cal B(D_s^+to mu^+ u_mu) = (5.35pm0.13pm0.16)times10^{-3}$, and the ratio of decay widths $R=frac{Gamma(D_s^+to tau^+ u_tau)}{Gamma(D_s^+to mu^+ u_mu)} = 9.73^{+0.61}_{-0.58}pm 0.36$, where the first uncertainties are statistical and the second systematic. No evidence of $CP$ asymmetry is observed in the decay rates $D_s^pmtomu^pm u_mu$ and $D_s^pmtotau^pm u_tau$: $A_{CP}(mu^pm u) = (-1.2pm2.7)%$ and $A_{CP}(tau^pm u) = (+2.9pm4.9)%$. Constraining our measurement to the Standard Model expectation of lepton universality ($R=9.75$), we find the more precise results $cal B(D_s^+to tau^+ u_tau) = (5.22pm0.10pm 0.14)times10^{-2}$ and $A_{CP}(tau^pm u_tau) = (-0.1pm2.1)%$. Combining our results with inputs external to our analysis, we determine the $cto s$ quark mixing matrix element, $D_s^+$ decay constant, and ratio of the decay constants: $|V_{cs}| = 0.973pm0.009pm0.014$, $f_{D^+_s} = 249.9pm2.4pm3.5~text{MeV}$, and $f_{D^+_s}/f_{D^+} = 1.232pm0.035$.
Using $567rm{pb}^{-1}$ of $e^+e^-$ collisions recorded at $sqrt{s}=4.599rm{GeV}$ with the BESIII detector, we report first measurements of absolute hadronic branching fractions of Cabibbo-favored decays of the $Lambda_{c}^{+}$ baryon with a double-ta
g technique. A global least-square fitter is utilized to improve the measured precision. Among the measurements for twelve $Lambda_{c}^{+}$ decay modes, the branching fraction for $Lambda_{c}^{+} rightarrow pK^-pi^+$ is determined to be $(5.84pm0.27pm0.23)%$, where the first uncertainty is statistical and the second is systematic. In addition, the measurements of the branching fractions of the other eleven Cabbibo-favored hadronic decay modes are significantly improved.
Using a sample of tagged D_s decays collected near the D^*_s D_s peak production energy in e+e- collisions with the CLEO-c detector, we study the leptonic decay D^+_s to tau^+ nu_tau via the decay channel tau^+ to e^+ nu_e bar{nu}_tau. We measure B(D
^+_s to tau^+ nu_tau) = (6.17 +- 0.71 +- 0.34) %, where the first error is statistical and the second systematic. Combining this result with our measurements of D^+_s to mu^+ nu_mu and D^+_s to tau^+ nu_tau (via tau^+ to pi^+ bar{nu}_tau), we determine f_{D_s} = (274 +- 10 +- 5) MeV.
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 r
ange $4.178 - 4.230$ 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.
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