No Arabic abstract
Using data collected by the fixed target Fermilab experiment FOCUS, we present several first measurements for the semileptonic decay $D^0 to bar{K}^0pi^-mu^+ u$. Using a model that includes a $bar{K}^0 pi^-$ S-wave component, we measure the form factor ratios to be r_v= 1.706+-0.677+-0.342 and r_2= 0.912+-0.370+-0.104 and the S-wave amplitude to be A=0.347+-0.222+-0.053 GeV^-1. Finally, we measure the vector semileptonic branching ratio $frac{Gamma(D^0 to K^{*}(892){-}mu^+ u)}{Gamma(D^0 to bar{K}^0pi^-pi^+)}= 0.337+-0.034+-0.013.
We present the results of a Dalitz plot analysis of D^0 to K^0_S pi^0 pi^0 using the CLEO-c data set of 818 inverse pico-barns of e^+ e^- collisions accumulated at sqrt{s} = 3.77 GeV. This corresponds to three million D^0 D^0-bar pairs from which we select 1,259 tagged candidates with a background of 7.5 +- 0.9 percent. Several models have been explored, all of which include the K^*(892), K^*_2(1430), K^*(1680), the f_0(980), and the sigma(500). We find that the combined pi^0 pi^0 S-wave contribution to our preferred fit is (28.9 +- 6.3 +- 3.1)% of the total decay rate while D^0 to K^*(892)^0 pi^0 contributes (65.6 +- 5.3 +- 2.5)%. Using three tag modes and correcting for quantum correlations we measure the D^0 to K^0_S pi^0 pi^0 branching fraction to be (1.059 +- 0.038 +- 0.061)%.
The Dalitz plot distribution of $B^0 rightarrow bar{D}^0 K^+ pi^-$ decays is studied using a data sample corresponding to $3.0rm{fb}^{-1}$ of $pp$ collision data recorded by the LHCb experiment during 2011 and 2012. The data are described by an amplitude model that contains contributions from intermediate $K^*(892)^0$, $K^*(1410)^0$, $K^*_2(1430)^0$ and $D^*_2(2460)^-$ resonances. The model also contains components to describe broad structures, including the $K^*_0(1430)^0$ and $D^*_0(2400)^-$ resonances, in the $Kpi$ S-wave and the $Dpi$ S- and P-waves. The masses and widths of the $D^*_0(2400)^-$ and $D^*_2(2460)^-$ resonances are measured, as are the complex amplitudes and fit fractions for all components included in the amplitude model. The model obtained will be an integral part of a future determination of the angle $gamma$ of the CKM quark mixing matrix using $B^0 rightarrow D K^+ pi^-$ decays.
Based on an $e^{+}e^{-}$ collision data sample corresponding to an integrated luminosity of 2.93 $mathrm{fb}^{-1}$ collected with the BESIII detector at $sqrt{s}=3.773 mathrm{GeV}$, the first amplitude analysis of the singly Cabibbo-suppressed decay $D^{+}to K^+ K_S^0 pi^0$ is performed. From the amplitude analysis, the $K^*(892)^+ K_S^0$ component is found to be dominant with a fraction of $(57.1pm2.6pm4.2)%$, where the first uncertainty is statistical and the second systematic. In combination with the absolute branching fraction $mathcal{B}(D^+to K^+ K_S^0 pi^0)$ measured by BESIII, we obtain $mathcal{B}(D^+to K^*(892)^+ K_S^0)=(8.69pm0.40pm0.64pm0.51)times10^{-3}$, where the third uncertainty is due to the branching fraction $mathcal{B}(D^+to K^+ K_S^0 pi^0)$. The precision of this result is significantly improved compared to the previous measurement.
Using an $e^+e^-$ annihilation data sample corresponding to an integrated luminosity of $2.93,rm fb^{-1}$ collected at a center-of-mass energy of 3.773 GeV with the BESIII detector, the doubly Cabibbo-suppressed decay $D^+to K^+pi^+pi^-pi^0$ is studied with a semileptonic tag method. After removing the decays containing narrow intermediate resonances, $D^+to K^+eta$, $D^+to K^+omega$, and $D^+to K^+phi$, the branching fraction for the decay $D^+to K^+pi^+pi^-pi^0$ is determined to be $(1.03 pm 0.12_{rm stat} pm 0.06_{rm syst})times 10^{-3}$. The ratio of the branching fraction for $D^+to K^+pi^+pi^-pi^0$ to its Cabibbo-favored counterpart $D^+to K^-pi^+pi^+pi^0$ is measured to be $ (1.65pm0.21)%$, corresponding to $(5.73pm0.73)tan^4theta_C$, where $theta_C$ is the Cabibbo mixing angle. These results are consistent with our previous measurement with hadronic tags but are significantly larger than other doubly Cabibbo-suppressed decays in the charm sector.
The K^+ to pi^0 mu^+ u gamma ($K_{mu 3 gamma}$) decay has been measured with stopped positive kaons at the KEK 12 GeV proton synchrotron. A $K_{mu 3 gamma}$ sample containing 125 events was obtained. The partial branching ratio $Br(K_{mu 3 gamma}, E_{gamma}>30 {rm MeV}, theta_{mu^+ gamma}>20^{circ})$ was found to be $[2.4 pm 0.5(stat) pm 0.6(syst)]times 10^{-5}$, which is in good agreement with theoretical predictions.