Bulletin of the American Physical Society
2007 APS April Meeting
Volume 52, Number 3
Saturday–Tuesday, April 14–17, 2007; Jacksonville, Florida
Session Y13: Bs |
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Sponsoring Units: DPF Chair: Matthew Herndon, Wisconsin University Room: Hyatt Regency Jacksonville Riverfront City Terrace 9 |
Tuesday, April 17, 2007 1:30PM - 1:42PM |
Y13.00001: Lifetime Difference and $CP$ Asymmetry in the $B_s^0 \to J/\psi \phi$ Mode Khaldoun Makhoul We report on the progress of the analysis of $B^0_s \to J/\psi \phi$ decays to extract the parameters $\Delta \Gamma_s / \Gamma_s$ and $\sin 2 \beta_s$ using 1.4~fb$^{-1}$ of data taken with the CDF\,II detector. The use of a time-dependent angular analysis can separate the $CP$~eigenstates of the $B^0_s$~meson to determine their separate lifetimes. Further tagging of the $B^0_s$ meson at time $t=0$ as $B^0_s$ or $\bar{B}^0_s$, allows for the analysis of the $CP$ asymmetry, which then yields the $\sin 2 \beta_s$ parameter. The $\Delta \Gamma_s$ measurement is an improved analysis using additional data, neural network selection for better signal/background, and reduced systematic errors. The $\sin 2 \beta_s$ measurement is the first such analysis at CDF. [Preview Abstract] |
Tuesday, April 17, 2007 1:42PM - 1:54PM |
Y13.00002: Measurement of the Branching Fraction for ${B}_{s} \rightarrow {D}_{s1}^{\pm}(2536) \mu \nu {X} \:$ at D0 Jason Rieger, Rick van Kooten The state ${B}^0_{s} \rightarrow {D}_{s1}^{\pm}(2536) \mu \nu {X} \:$ has been observed at D0 through the decay channel ${D}_{s1}^ {\pm}(2536) \rightarrow {D}^{* \pm} K^0_S \:$ with $D^{*+}$ $\rightarrow$ ${D^0}$ $\pi^+$, ${D^0}$ $\rightarrow K^- \pi^+$ and $K_S^0 \rightarrow \pi^+ \pi^-$. The branching fraction for this $B^0_s$ semileptonic decay to an orbitally excited $D_s$ state is measured for the first time and the ${D}_{s1}^{\pm}(2536)\:$ mass peak is presented with a signal significance of greater than 5.0 sigma in approximately 1.3 fb$^{-1}$ of data from the D0 detector. [Preview Abstract] |
Tuesday, April 17, 2007 1:54PM - 2:06PM |
Y13.00003: Measurement of the $B^0_s$ Width Difference and Mixing Phase in the Decay $B^0_s\rightarrow J/\psi \phi$ Avdhesh Chandra In the standard model (SM), the light ($L$) and heavy ($H$) mass eigenstates of the mixed ($B^0_s$, $\bar{B^0_s}$) system are expected to have a sizable mass and decay width difference, $\Delta M \equiv M_H - M_L$ and $\Delta \Gamma \equiv \Gamma_L - \Gamma_H$. The CP violating phase, $\phi_{s}$, defined as the relative phase of the off-diagonal elements of the mass and decay matrices in the $B^0_s$ $-$ $\bar{B^0_s}$ basis, is predicted to be small. From an analysis of the ``untagged'' $B^0_s\rightarrow J/\psi \phi$ time-dependent angular distributions, we measure the average lifetime ($\overline \tau$), $\Delta \Gamma$, and $\phi_ {s}$. To improve the sensitivity of the measurement, we have extended this analysis by using flavor tagging information when available. [Preview Abstract] |
Tuesday, April 17, 2007 2:06PM - 2:18PM |
Y13.00004: Study of $B^{**}$ and $B_s^{**}$ Mark Williams Using 1.3 fb$^{-1}$ of data collected with the D0 detector at the Tevatron, the excited states containing a $b$ quark $B_1$, $B_2^*$ and $B_ {s2}^*$ are selected in exclusive decays. A precise measurement of their masses, widths and branching rates is reported. [Preview Abstract] |
Tuesday, April 17, 2007 2:18PM - 2:30PM |
Y13.00005: $B_s$ Mixing at D0 Meghan Anzelc We report results on the determination of the $B_s$ oscillation frequency using a large data set taken at the D0 experiment during RunII at the Tevatron. We search for oscillations in the time dependence of flavor specific $B_s$ decays where the flavor of the $B_s$ at production is determined by studying inclusive properties of the event. [Preview Abstract] |
Tuesday, April 17, 2007 2:30PM - 2:42PM |
Y13.00006: Selection of Fully Reconstructed Hadronic $B_s^0$ Decays for the Observation of $B^0_s$-$\bar B_s^0$ Oscillations Bruno Casal We present the neural network based selection of hadronic $B_s^0$ decay modes used for the time-dependent measurement of $B^0_s$-$\bar B_s^0$ oscillation frequency $\Delta m_s$. Using a data sample of 1~fb$^{-1}$ of $p\bar p$ collisions at $\sqrt s=1.96$~TeV collected with the CDF\,II detector at the Fermilab Tevatron Collider, we find signals of 5600 fully reconstructed hadronic $B_s^0$ decays. We measure the probability as a function of proper decay time that the hadronic $B^0_s$ candidate decays with the same or opposite flavor as the flavor at production. We find a signal for $B_s$-$\bar B_s$ oscillations and measure $\Delta m_s$ = 17.77 $\pm$ 0.10 (stat) $\pm$ 0.07 (syst) ps$^{-1}$. From this we extract $|V_{td}/V_{ts}|$ = 0.2060 $\pm$ 0.0007 (exp) + 0.0081 - 0.0060 (theor). [Preview Abstract] |
Tuesday, April 17, 2007 2:42PM - 2:54PM |
Y13.00007: Measurement of branching fractions for $B_s^0\rightarrow J/\psi \phi$ and $B_s^0\rightarrow J/\psi K_s^0$ decays at $\Upsilon(5S)$ Kazi Sayeed, Alan Schwartz We measure the branching fractions for $B_s^0\rightarrow J/\psi \phi$ and $B_s^0\rightarrow J/\psi K_s^0$ decays using a \sim23.5 $ fb^{-1}$ data sample collected on the $\Upsilon(5S)$ resonance by the Belle detector at the KEKB asymmetric energy $e^+e^-$ collider. The $J/\psi$ candidates are reconstructed from both $e^+e^-$ and $\mu^+\mu^-$ pairs; $\phi$ candidates are reconstructed from $K^+K^-$ pairs and $K_s^0$ candidates from $\pi^+\pi^-$ pairs. [Preview Abstract] |
Tuesday, April 17, 2007 2:54PM - 3:06PM |
Y13.00008: Measurement of the Charge Asymmetry in Semileptonic $B^0_s$ Decays Kostyantyn Holubyev We have performed the first direct measurement of the time integrated, flavor untagged, charge asymmetry in semileptonic $B^0_s$ decays, $A_{SL}^{s,unt} $, by comparing the decay rate of $B^0_s\rightarrow \mu^+D^-_s\nu X$, where $D^- _s\rightarrow \phi\pi^-$ and $\phi\rightarrow K^+K^-$, with the charge-conjugate ${\bar B} ^0_s$ decay rate. This sample was selected from $1.3$ fb$^{-1}$ of data collected by the D0 experiment in Run II of the Fremilab Tevatron collider. We obtain $A_{SL}^{s,unt} = (1.23 \pm 0.97 \pm 0.17)\%$ which can be translated to a measurement of the CP-violating phase in $B^0_s$ mixing: $(\Delta \Gamma_s/\Delta m_s)\tan \phi_s = (2.45\pm 1.93\pm 0.35)\%$. [Preview Abstract] |
Tuesday, April 17, 2007 3:06PM - 3:18PM |
Y13.00009: Observation of the $B^0_s\to K^-\pi^+$, $\Lambda^{0}_b\to p\pi^{-}$ and $\Lambda^{0}_b\to p K^{-}$ Modes at CDF Guido Volpi We report the first observation of the charmless decays modes $B^0_s\rightarrow K^-\pi^+$, $\Lambda^{0}_b\rightarrow p\pi^{-}$, $\Lambda^{0}_b\rightarrow p K^{-}$ using 1 fb$^{-1}$ of CDF data. All three modes are expected to exhibit significant direct-$CP$~asymmetries, of which we present preliminary measurements. The new modes are separated from other larger-yield two-prong charmless modes by means of a global kinematic-PID fit, including a detailed model of QED radiation effects and non-Gaussian resolution tails. [Preview Abstract] |
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