Session W12: D and B Physics

Study of $D\to K/\pi e \nu_e$ and measurement of $|V_{cs}|$ and $|V_{cd}|$

Using a 281 pb$^{-1}$ data sample comprised of 1.8 million $D \bar{D}$ mesons collected at the $\psi(3770)$ with the CLEO-c detector, we measure absolute branching fractions as a function of $q^2$, the invariant mass of the $e^+ \nu_e$ pair, for $D^0 \to K^- e^+ \nu_e$, $D^0 \to \pi^- e^+ \nu_e$, $D^+\to K_S^0 e^+ \nu_e$ and $D^+ \to \pi^0 e^+ \nu_e$. We measure the absolute magnitudes of the form factors $f^+_{K}(0)$ and $f^+_{\pi}(0)$. Using unquenched lattice QCD calculations of the form factor normalizations we extract the magnitudes of the CKM matrix elements $V_{cs}$ and $V_{cd}$. Our measurement of $|V_{cs}|$ is the most precise direct determination to date. An extension of the analysis with the $\approx 800~pb^{-1}$ complete data set is also discussed.   

Search for CP violation in $D^{\pm}\rightarrow K^{\pm}K^{\mp}\pi^{\pm}$

We present a search for the direct CP asymmetry in the singly Cabibbo- suppressed decays {$D^{\pm}\rightarrow K^{\pm}K^{\mp}\pi^{\pm}$ } based on a data sample of 468 fb$^{-1}$ recorded by the BaBar detector. We report on the results of a simultaneous fit of the $D^{+}$ and $D^{-}$ Dalitz plots to measure the asymmetry in the resonant and non-resonant components.   

Model-Independent Partial-Wave Analysis of $D^+\to K^-\pi^+\pi^+$

We report a preliminary result of a model-independent partial-wave analysis of the $D^+\to K^-\pi^+\pi^+$ decay. The decay provides a good sample to improve our knowledge of the partial-wave structures in the $K\pi$ system from such decays. The analysis is performed using data collected by the BaBar detector at the PEP-II asymmetric-energy $e^+ e^-$ storage rings at SLAC. A high-statistics sample enables us to perform the analysis without employing theoretical models in the $S$- and $P$-wave parameterizations. The result may provide a useful application in heavy-flavor physics.   

Measurement of the $D^0 \rightarrow \phi \eta$ Branching Fraction

We present a preliminary result for branching fraction measurement of the decay $D^0 \rightarrow \phi \eta$ 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.   

Study of $B$ meson decays to $\eta K \gamma$ final states

We present measurements of the branching fraction and integrated CP asymmetry for charged $B$ meson decays to $\eta K \gamma$, and the branching fraction and time-dependent CP asymmetry for neutral $B$ meson decays to $\eta K^0 \gamma$. Our measurements are based on data collected from 1999-2007 with the BaBar detector at the PEP-II asymmetric-energy $e^+e^-$ collider at SLAC.   

A Measurement of the Direct CP Asymmetry in the Decay $b \to s \gamma$

We present a measurement of the direct CP asymmetry in the rare Standard Model decay $b \to s \gamma$ using 380 million $B\bar{B}$ events collected by the BaBar experiment at the PEP-II $B$-factory. In the Standard Model, direct CP violation in this process is expected to be $<1$\%, while in new physics models (such as the Minimal Supersymmetric Standard Model) it can be as high as 15\%. We select this rare decay by fully reconstructing the $B$ meson decay into a fragmented $s$-quark and a photon using many exclusive final states of the $B$ decay.   

Time-dependent analysis of $B^0 \to \rho^0 \rho^0$ decays

We study the decay $B^0 \to \rho^0 \rho^0$ in a sample of about 454 million $\Upsilon (4S)\rightarrow B \bar{B}$ decays collected with the Babar detector at the PEP-II asymmetric-energy $e^+e^-$ collider at SLAC. We measure the branching fraction and longitudinal polarization fraction. We investigate the proper-time dependence of the longitudinal component in the decay and measure the $C\!P$-violating coefficients $S^{00}_L$ and $C^{00}_L$, corresponding to the sine and cosine terms in the time evolution of the CP asymmetry. We study the implication of these results for the CKM unitarity angle $\alpha$.   

Measurement of branching ratios for two-pion transitions in the bottomonium system

Using approximately 9 million $\Upsilon(2S)$ decays and 6 million $\Upsilon(3S)$ decays, the CLEO Collaboration has made new measurements of the branching ratios for charged (via $\pi^{+}\pi^{-}$) and neutral (via $\pi^{0}\pi^{0}$) transitions among the three lowest-lying $\Upsilon(nS)$ states.   

Measurement of $\gamma$ using a $D$ Dalitz analysis of $B^\pm \to D^{(*)} K^{(*)\pm}$ decays

We report on an improved measurement of the Cabibbo-Kobayashi-Maskawa CP-violating phase $\gamma$ through a Dalitz analysis of neutral $D$ decays to $K^0_S \pi^+ \pi^-$ and $K^0_S K^+ K^-$ in the processes $B^\mp \to D K^\mp$, $B^\mp \to D^* K^\mp$ with $D^* \to D \pi^0,D\gamma$, and $B^\mp \to D K^{*\mp}$ with $K^{*\mp} \to K^0_S \pi^\mp$. The analysis is based on a sample of 383 million $B \bar B$ pairs collected by the BaBar detector at the PEP-II asymmetric-energy $e^+e^-$ collider at SLAC.