Session L11: Charm Physics

Evidence for $D^0$-$\bar{D}^0$ Mixing Using the CDF~II Detector

We measure the time dependence of the ratio of decay rates for the rare decay $D^0 \rightarrow K^+\pi^-$ to the Cabibbo-favored decay $D^0 \rightarrow K^-\pi^+$. We use a signal of $12.7 \times 10^3$ $D^0 \rightarrow K^+\pi^-$ decays with proper decay times between 0.75 and 10 mean $D^0$ lifetimes. The data sample was recorded with the CDF~II detector at the Fermilab Tevatron and corresponds to an integrated luminosity of 1.5 fb$^{-1}$ for $p\bar{p}$ collisions at $\sqrt{s}$ = 1.96 TeV. We search for $D^0$-$\bar{D}^0$ mixing and measure the mixing parameters to be $R_D = (3.04 \pm 0.55) \times 10^{-3}$, $y' = (8.5 \pm 7.6) \times 10^{-3}$, and $x'^2 = (-0.12 \pm 0.35) \times 10^{-3}$. We report Bayesian probability contours in the $x'^2$-$y'$ plane and find that the data are inconsistent with the no-mixing hypothesis with a probability equivalent to 3.8 Gaussian standard deviations. Potential updates to the analysis will be presented.   

Measurements of D decay at CLEO-c related to the determination of the unitarity triangle angle $\gamma$

One of the principal goals of flavour physics is the accurate determination of the unitarity triangle angle $\gamma$. Several of the theoretically cleanest strategies to determine $\gamma$ use $B\rightarrow DK$ decays, where the $D$ is either a $D^{0}$ or $\bar{D^{0}}$ decaying to the same hadronic final state. The full exploitation of these decays requires excellent knowledge of the parameters and amplitudes of the $D$ decay, particularly if the $D$ decays to a three or four-body final state. The best environment to determine the $D$-decay parameters are quantum correlated $D^{0}\bar{D^{0}}$ decays produced in $e^{+}e^{-}$ collisions at a centre-of-mass energy equal to the mass of the $\psi(3770)$. We report preliminary results from the CLEO-c experiment of some of the parameters relevant to the determination $\gamma$ in $B$-decay.   

Study of the decay $D^{0} \rightarrow \gamma \gamma$

We present preliminary results for the decay $D^{0} \rightarrow \gamma \gamma$ using data collected with the BaBar detector at the PEP-II asymmetric $e^{+} e^{-}$ collider at SLAC. We fully reconstruct the decay $D^{ *} \rightarrow D^0\pi^+$,$D^{0} \rightarrow \gamma \gamma$. These predominantly long-range, FCNC decays provide a test for physics beyond the standard model.   

Radiative decays of $\chi_c$ states to light vector mesons

Using approximately 25 million decays of the $\psi(2S)$ collected with the CLEO-c detector we study decays of the $\chi_c$ states produced in radiative decays of the $\psi(2S)$. In particular we present results of a search for rare radiative decays of the $\chi_c$ states to light vector mesons.   

Dalitz Plot Analysis of $D^0 \rightarrow K^0_S \pi^+ \pi^-$ and $D^0 \rightarrow K^0_S K^+ K^-$

We present a Dalitz plot analysis of the decays $D^0 \rightarrow K^0_S \pi^+ \pi^-$ and $D^0 \rightarrow K^0_S K^+ K^-$ using data collected by the BaBar detector at the PEP-II asymmetric-energy $e^+e^-$ collider at SLAC. The results of this analysis are a critical input for the determination of the Cabibbo-Kobayashi-Maskawa CP-violating phase $\gamma$ using a $D$ Dalitz analysis of $B^\pm \to D^{(*)} K^{(*)\pm}$ decays.   

Search for the Decay $D^0 \rightarrow \omega \eta$

We present a preliminary result of the search for the decay $D^0 \rightarrow \omega \eta$ where $D^0$ comes from the decay $D^{*+} \rightarrow D^0 \pi^+$. We use a high statistics data sample collected with the BaBar detector at the PEP-II asymmetric $e^{+} e^{-}$ collider at SLAC.   

First measurement of the form factors in $D\to \rho e^+ \nu_e$

Using a 281 pb$^{-1}$ data sample collected with the CLEO-c detector at the $\psi(3770)$ resonance, we present improved measurements of absolute branching fractions in the semileptonic decays $D^0 \to \rho^- e^+ \nu_e$ and $D^+ \to \rho^0 e^+ \nu_e$. By performing a four-dimensional maximum likelihood fit to the distribution of kinematic variables, we have measured, for the first time, the semileptonic form factors in these modes. An extension of the analysis with the $\approx 800$~pb$^{-1}$ complete data set is also discussed.   

Search for the Decay $D^0 \rightarrow K^* \eta$

We present a preliminary result of the search for the DCS decay $D^0 \rightarrow K^* \eta$ where $D^0$ comes from the decay $D^{*+} \rightarrow D^0 \pi^+$. We use a high statistics data sample collected with the BaBar detector at the PEP-II asymmetric $e^{+} e^{-}$ collider at SLAC.