Bulletin of the American Physical Society
APS April Meeting 2011
Volume 56, Number 4
Saturday–Tuesday, April 30–May 3 2011; Anaheim, California
Session R9: Charm and B Physics II |
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Sponsoring Units: DPF Chair: Kevin Pitts, University of Illinois at Urbana-Champaign Room: Grand G |
Monday, May 2, 2011 1:30PM - 1:42PM |
R9.00001: Study of $B \to D^{(*)} \ell \nu$ and $|V_{cb}|$ with full reconstruction of $B$ mesons in {\sc BaBar} data Chiara Piacentini We present preliminary results of an improved analysis for the measurement of the branching fraction of the decays $B \to D^{(*)} \ell \nu$. Study of these decays allows the determination of the Cabibbo-Kobayashi-Maskawa (CKM) matrix element $|V_{cb}|$. Precise determination of $|V_{cb}|$ may impose further constraints on the (CKM) unitarity triangle. These results are based on a sample of about 470M $B\bar B$ pairs collected by the {\sc BaBar} detector at the PEP-II $e^+e^-$ asymmetric-energy collider, located at SLAC National Accelerator Laboratory. [Preview Abstract] |
Monday, May 2, 2011 1:42PM - 1:54PM |
R9.00002: Study of $B^- \to \omega \ell^- \bar\nu_\ell$ decays at {\sc BaBar} H. Wells Wulsin We present an analysis of $B^- \to \omega \ell^- \bar\nu_\ell$ decays based on a sample of 470 million $B\overline{B}$ pairs recorded with the {\sc BaBar} detector at the $\Upsilon(4S)$ resonance. We use a data sample from the sidebands of the $m_{3\pi}$ distribution to model the combinatoric $\omega$-candidates background, which is the largest source of background. We measure the branching fraction for this decay in three bins of $q^2$, the squared momentum transfer, and compare the distribution with predictions based on theoretical form-factor calculations. [Preview Abstract] |
Monday, May 2, 2011 1:54PM - 2:06PM |
R9.00003: Measurement of the exclusive semileptonic decays $B\to D\tau^-\bar\nu_\tau$ and $B\to D^*\tau^-\bar\nu_\tau$ at {\sc BaBar} Manuel Franco Sevilla We present measurements of the branching fractions of the exclusive semileptonic decays $B\to D\tau^-\bar\nu_\tau$ and $B\to D^*\tau^-\bar\nu_\tau$. The analysis uses $471$ million $B\bar B$ pairs, the full data sample collected by the {\sc BaBar} detector at the PEP-II $e^+e^-$ asymetric-energy collider, located at SLAC National Accelerator Laboratory. We select events with a $D$ or $D^*$ meson and a light lepton ($e$ or $\mu$) recoiling against a fully-reconstructed $B$ meson. We perform a joint fit to the lepton spectrum and the squared-missing-mass distribution to discriminate signal events from the background, which is predominantly $B\to D^{(*)}\ell^-\bar\nu_\ell$. A control sample of identified $D^{**}\ell^-\bar\nu_\ell$ events is included in the fit to estimate the background contribution from these decays. [Preview Abstract] |
Monday, May 2, 2011 2:06PM - 2:18PM |
R9.00004: Precision measurement of the $B_{s}$ lifetime using the channel $B^{0}_s\rightarrow D_s^{+}\mu X$ Jorge Martinez-Ortega We report a measurement of the lifetime of the $B^{0}_{s}$ meson, using the semileptonic channel $B^{0}_s\rightarrow D^{+}_s\mu X$. We use 8.9 fb$^{-1}$ of data collected by the D$\O{}$ experiment. This is the most precise measurement of $B^{0}_{s}$ lifetime reported to date. [Preview Abstract] |
Monday, May 2, 2011 2:18PM - 2:30PM |
R9.00005: Measurement of the ${\mathcal{B}} (\Lambda^0_{b} \rightarrow J/\Psi \Lambda_0)$ using 6.1 fb$^{-1}$ of D0 data Enrique Camacho We report a new measurement of the branching ratio ${\mathcal{B}} (\Lambda^0_{b}\to J/\psi \Lambda_0)$ using 6.1 fb$^{-1}$ of $p \overline{p}$ collisions at $\sqrt{s}=1.96$ TeV recorded by the D0 detector at Fermilab, between 2002 and 2009. The uncertainty in the new measurement of ${\mathcal{B}} (\Lambda^0_{b}\to J/\psi \Lambda_0)$ was reduced to half of the uncertainty in the world average from the PDG. We also report a new measurement of the the production cross-section times the branching fraction for the decay $\Lambda^0_{b} \rightarrow J/\Psi \Lambda_0$ relative to that for the decay $B^0_d \rightarrow J/\Psi K^{0}_{s}$. [Preview Abstract] |
Monday, May 2, 2011 2:30PM - 2:42PM |
R9.00006: Measurement of the branching fractions of $B_s^{0} \rightarrow D_s^{(*)+} D_s^{(*)-}$ decays at CDF Dominik Horn, Michael Feindt, Thomas Kuhr, Michal Kreps The CDF collaboration reports on an improved measurement of $B_s^{0} \rightarrow D_s^{(*)+} D_s^{(*)-}$ branching fractions using 5.3 fb$^{-1}$ of data. The $D_s^{+}$ meson is reconstructed by selecting two narrow mass bands of phase space of the $KK\pi$ final state and accounting for the full $KK\pi$ Dalitz structure in the reconstruction efficiencies for the first time. Assuming the semi-inclusive final state $D_s^{(*)+} D_s^{(*)-}$ to be predominantly CP even and CP violation in $B_{s}^{0}$ mixing negligible, this measurement probes directly the relative decay width difference $\Delta\Gamma_{s}/\Gamma_{s}$. [Preview Abstract] |
Monday, May 2, 2011 2:42PM - 2:54PM |
R9.00007: Measurement of the $B_s \to J/\psi\phi$ Production Cross Section in $pp$ Collisions at $\sqrt{s} = 7$ TeV in the CMS experiment at LHC Giordano Cerizza I present measurements of the differential production cross section in bins of transverse momentum, $d\sigma/dp_T$, and rapidity, $d\sigma/d|y|$, for the decay $B_s \to J/\psi\phi$ in proton-proton collisions at $\sqrt{s} = 7$~TeV. The data correspond to an integrated luminosity of 40 pb$^{-1}$ collected by the Compact Muon Solenoid experiment operating at the CERN Large Hadron Collider in 2010. The $B_s$ decay is fully reconstructed with $J/\psi$ decaying into $\mu^+\mu^-$ and $\phi$ into $K^+K^-$. The cross section measurements are compared to several theoretical predictions. [Preview Abstract] |
Monday, May 2, 2011 2:54PM - 3:06PM |
R9.00008: Measurement of the Inclusive $\Upsilon$ production cross section in $pp$ collisions at $\sqrt{s}=7$~TeV Yu Zheng The $\Upsilon$ production cross section in proton-proton collisions at $\sqrt{s} = 7$~TeV is measured using a data sample collected with the CMS detector at the LHC, corresponding to an integrated luminosity of $3.1 \pm 0.3$ pb$^{-1}$. Integrated over the rapidity range $|y|<2$, we find the product of the $\Upsilon(1S)$ production cross section and branching fraction to dimuons to be $\sigma(pp \to \Upsilon(1S) X) B(\Upsilon(1S) \to \mu^+ \mu^-) = 7.37 \pm 0.13^{+0.61}_{-0.42}\pm 0.81$~nb, where the first uncertainty is statistical, the second is systematic, and the third is associated with the estimation of the integrated luminosity of the data sample. This cross section is obtained assuming unpolarized $\Upsilon(1S)$ production. If the $\Upsilon(1S)$ production polarization is fully transverse or fully longitudinal the cross section changes by about 20\%. We also report the measurement of the $\Upsilon(1S)$, $\Upsilon(2S)$, and $\Upsilon(3S)$ differential cross sections as a function of transverse momentum and rapidity. [Preview Abstract] |
Monday, May 2, 2011 3:06PM - 3:18PM |
R9.00009: Measurement of $\Upsilon(1S)$ polarization using CMS Matthew Rudolph I present plans to measure the polarization of promptly produced $\Upsilon(1S)$ mesons in proton-proton collisions at $\sqrt{s}= 7$~TeV using the decay to two muons at the CMS detector. The method is outlined and preliminary results using approximately 40 pb$^{-1}$ are presented. The full angular distribution of the muons is measured as a function of the $\Upsilon$ $p_T$ and rapidity, and the analysis is conducted using two coordinate frames. [Preview Abstract] |
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