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Register a new userObservation of the semi-muonic decay $D^+to omegamu^+ u_mu$
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We report the first observation of the semi-muonic decay $D^+to omega mu^+ u_mu$ using an $e^+e^-$ collision data sample corresponding to an integrated luminosity of $2.93~mathrm{fb}^{-1}$ collected with the BESIII detector at a center-of-mass energy of 3.773 GeV. The absolute branching fraction of the $D^+to omega mu^+ u_mu$ decay is measured to be ${mathcal B}_{D^+to omegamu^+ u_mu}=(17.7pm1.8_{rm stat}pm1.1_{rm syst})times 10^{-4}$. Its ratio with the world average value of the branching fraction of the $D^+to omega e^+ u_e$ decay probes lepton flavor universality and it is determined to be ${mathcal B}_{D^+to omega mu^+ u_mu}/{mathcal B}^{rm PDG}_{D^+to omega e^+ u_e}=1.05pm0.14$, in agreement with the standard model expectation within one standard deviation.
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By analyzing an $e^+e^-$ annihilation data sample corresponding to an integrated luminosity of $2.93~mathrm{fb}^{-1}$ collected at a center-of-mass energy of 3.773 GeV with the BESIII detector, we measure the branching fraction of the $D^0to rho^- mu^+ u_mu$ decay for the first time. We obtain ${mathcal B}_{D^0to rho^- mu^+ u_mu}=(1.35pm0.09_{rm stat}pm0.09_{rm syst})times 10^{-3}$. Combining with theoretical predictions, we extract the CKM matrix element $|V_{cd}|=0.204pm0.007_{rm stat}pm0.007_{rm syst}pm0.014_{rm theory}$. Using the world average of ${mathcal B}_{D^0to rho^- e^+ u_e}$, we find a branching fraction ratio of ${mathcal B}_{D^0to rho^- mu^+ u_mu}/{mathcal B}_{D^0to rho^- e^+ u_e}=0.90pm0.11$, which agrees with the theoretical expectation of lepton flavor universality within the uncertainty. Combining the world average of ${mathcal B}_{D^+to rho^0 mu^+ u_mu}$ and the lifetimes of $D^{0(+)}$, we obtain a partial decay width ratio of ${Gamma}_{D^0to rho^- mu^+ u_{mu}}/(2{Gamma}_{D^+to rho^0 mu^+ u_{mu}}) = 0.71pm0.14$, which is consistent with the isospin symmetry expectation of one within $2.1sigma$. For the reported values of ${mathcal B}_{D^0to rho^- mu^+ u_mu}/{mathcal B}_{D^0to rho^- e^+ u_e}$ and ${Gamma}_{D^0to rho^- mu^+ u_{mu}}/2{Gamma}_{D^+to rho^0 mu^+ u_{mu}}$, the uncertainty is the quadratic sum of the statistical and systematic uncertainties.
By analyzing a data sample corresponding to an integrated luminosity of $2.93~mathrm{fb}^{-1}$ collected at a center-of-mass energy of 3.773 GeV with the BESIII detector, we measure for the first time the absolute branching fraction of the $D^+to eta mu^+ u_mu$ decay to be ${mathcal B}_{D^+to eta mu^+ u_mu}=(10.4pm1.0_{rm stat}pm0.5_{rm syst})times 10^{-4}$. Using the world averaged value of ${mathcal B}_{D^+to eta e^+ u_e}$, the ratio of the two branching fractions is determined to be ${mathcal B}_{D^+to eta mu^+ u_mu}/{mathcal B}_{D^+to eta e^+ u_e}=0.91pm0.13$, which agrees with the theoretical expectation of lepton flavor universality within uncertainty. Here, the uncertainty is the sum in quadrature of the statistical and systematic uncertainties. By studying the differential decay rates in five four-momentum transfer intervals, we obtain the product of the hadronic form factor $f^{eta}_{+}(0)$ and the $cto d$ Cabibbo-Kobayashi-Maskawa matrix element $|V_{cd}|$ to be $f_{+}^eta (0)|V_{cd}|=0.087pm0.008_{rm stat}pm0.002_{rm syst}$. Taking the input of $|V_{cd}|$ from the global fit in the standard model, we determine $f_{+}^eta (0)=0.39pm0.04_{rm stat}pm0.01_{rm syst}$. On the other hand, using the value of $f_+^{eta}(0)$ calculated in theory, we find $|V_{cd}|=0.242pm0.022_{rm stat}pm0.006_{rm syst}pm0.033_{rm theory}$.
We report the first observation of $D^+totau^+ u_tau$ with a significance of $5.1sigma$. We measure ${cal B}(D^+totau^+ u_tau) = (1.20pm0.24_{text{stat.}}pm0.12_{text{syst.}})times10^{-3}$. Taking the world average ${cal B}(D^+tomu^+ u_mu) = (3.74pm0.17)times10^{-4}$, we obtain $R_{tau/mu} =Gamma(D^+totau^+ u_tau)/Gamma(D^+tomu^+ u_mu) = 3.21pm0.64_{text{stat.}}pm0.43_{text{syst.}}$, which is consistent with the Standard Model expectation of lepton flavor universality. Using external inputs, our results give values for the $D^+$ decay constant $f_{D^+}$ and the CKM matrix element $|V_{cd}|$ that are consistent with, but less precise than, other determinations.
The $B^+ to D^{*-}K^+pi^+$ decay potentially provides an excellent way to investigate charm meson spectroscopy. The decay is searched for in a sample of proton-proton collision data collected with the LHCb detector at centre-of-mass energies of 7 and 8 TeV, corresponding to an integrated luminosity of $3~{rm fb}^{-1}$. A clear signal is observed, and the ratio of its branching fraction to that of the $B^+ to D^{*-}pi^+pi^+$ normalisation channel is measured to be begin{equation*} frac{mathcal{B}(B^+ to D^{*-}K^+pi^+)}{mathcal{B}(B^+ to D^{*-}pi^+pi^+)} = left( 6.39 pm 0.27 pm 0.48 right) times 10^{-2} , , end{equation*} where the first uncertainty is statistical and the second is systematic. This is the first observation of the $B^+ to D^{*-}K^+pi^+$ decay.
Using a data sample corresponding to an integrated luminosity of 2.93 fb$^{-1}$ collected at a center-of-mass energy $sqrt{s}=3.773$ GeV by the BESIII detector, the decay $D^0toomegaphi$ is observed for the first time. The branching fraction is measured to be $(6.48 pm 0.96 pm 0.38)times 10^{-4}$ with a significance of $6.3 sigma$, where the first and second uncertainties are statistical and systematic, respectively. An angular analysis reveals that the $phi$ and $omega$ mesons from the $D^0 to omega phi$ decay are transversely polarized.
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