Bulletin of the American Physical Society
2005 APS April Meeting
Saturday–Tuesday, April 16–19, 2005; Tampa, FL
Session E11: QCD |
Hide Abstracts |
Sponsoring Units: DPF Chair: John Womersley, Fermilab Room: Marriott Tampa Waterside Room 7 |
Saturday, April 16, 2005 3:30PM - 3:42PM |
E11.00001: The total hadronic cross section in $e^{+}e^{-}$ annihilation at 7.0-10.3 GeV Surik Mehrabyan \begin{document} We present preliminary measurements of the $e^{+}e^{-}$ annihilation hadronic cross section using the CLEO detector at the Cornell Electron Storage Ring. High statistics data sets at total c.m. energies 10.3, 8.4, 7.4, and 7.0 GeV have been used in our analysis. Our results have been compared with previous measurements in the same energy range. When divided by the bare $e^{+}e^{-} \rightarrow \mu^+ \mu^-$ total cross section, $R(s)$ is obtained. This has importance in dispersion relation calculations of the hadronic corrections to various fundamental quantities. \end{document} [Preview Abstract] |
Saturday, April 16, 2005 3:42PM - 4:06PM |
E11.00002: Study of Charm Pair Production at Tevatron Burkard Reisert We present the first measurement of charm pair production at a hadron collider. We have measured the doubly differential cross section $d^2\sigma/dpt(D^0)dpt(D^{*-})$ for prompt charm meson pairs in a 360 pb-1 sample of p anti-p collisions at $s^(1/2)$ = 1.96 TeV from the CDF II detector at the Fermilab Tevatron. The measurement is made using fully reconstructed charm meson pairs. In order to provide additional information about the production process we measure the cross section separately for the two mesons in the same and opposite hemispheres. [Preview Abstract] |
Saturday, April 16, 2005 4:06PM - 4:18PM |
E11.00003: Preliminary measurement of the b-jet cross section at CDF Run-II Greg Williams We present preliminary results on the inclusive b-jet cross sectionas a function of P$_T{^{jet}}$ using data collected by the CDF experiment from proton-antiproton collisions at $\sqrt{s}$ = 1.96 TeV. Jets are defined using the midpoint cone algorithm, and heavy flavor jets are tagged using a probability constructed from the impact parameters of charged tracks within the jets. The experimental measurements are compared to theoretical predictions. [Preview Abstract] |
Saturday, April 16, 2005 4:18PM - 4:30PM |
E11.00004: Probing strange quark in proton using $p\bar{p}\rightarrow Wc$ at D$\O$} Mahsana Ahsan I will describe a measurement of s-quark parton distribution function(PDF) using the D$\O$ detector at Fermilab Tevatron. As s-quark PDF has only been measured in $\nu$N deep inelastic scattering, it is important to know if the same PDF works in $p\bar{p}$ inelastic experiments at $\sqrt{s}=1.96$TeV. Importance of the measurement of s-quark PDF also arises in the tests of QCD and EW dynamics and the background measurements of the New Physics processes(e.g $\tilde{t} \rightarrow c \tilde{\chi^o}$). To measure s-quark PDF I chose to study $ W + c $ production in $p\bar{p}$ collisions via the parton level processes $sg\rightarrow W^-c$ , $\bar{s}g\rightarrow W^+ \bar{c}$, $dg\rightarrow W^-c$ or $g\bar{d}\rightarrow W^+\bar{c}$, where $d$-quark and gluon fusion contribute about 15$\%$ of the total $Wc$ production rate. The ratio of $W+c$ cross section to the inclusive $W+1j$, is of the order of $10^{-2}$ - dependent on the Pt of the jet. A study of the sensitivity of this ratio to the parametrization of the s-quark PDF may eventually allow us to determine a precise distribution function. Current status of analysis is the studies of charm tagging efficiencies in MC, the event selection efficiencies and signal to background ratios. [Preview Abstract] |
Saturday, April 16, 2005 4:30PM - 4:42PM |
E11.00005: Study of the Decay $B^- \rightarrow D_J^0 \pi^-$ Jong Yi Excited states of the $D$ meson, typically denoted as $D_J$ (or $D^{**}$), provide a unique opportunity to test Heavy Quark Effective Theory (HQET). For one unit of angular momentum ($L = 1$), there are four states of positive parity labeled $D_1$, $D_0^*$, $D_1^{'}$, and $D_2^*$. According to HQET, the $D_1$ decays via a $D$-wave to $D^*\pi$ whereas the $D_2^*$ can decay via $D$-wave to either $D^*\pi$ or $D\pi$. The $D_0^*$ and $D_1^{'}$ should decay via an $S$-wave to $D\pi$ and $D^{*}\pi$ respectively, and are expected to be rather broad. We report here on the Dalitz plot analyses of $B^-$ mesons decaying into $D^{(*)+}\pi^-\pi^-$ final states using 230 million $B^-$ decays collected by the BaBar detector at the PEP-II asymmetric $B$ Factory. [Preview Abstract] |
Saturday, April 16, 2005 4:42PM - 4:54PM |
E11.00006: $J/\psi$ Spin Alignment in $p \overline{p}$ Collisions at $\sqrt{s} = 1.96$ TeV Min-Jeong Kim We have measured the spin alignment of prompt $J/\psi$ mesons
produced in $p\overline{p}$ collisions at $\sqrt{s}=1.96 {\rm TeV}$
using data collected by CDF II detector. The $J/\psi$ mesons
are reconstructed by $J/\psi\rightarrow\mu\mu$ decays and
promptly produced $J/\psi$ mesons are separated from those
produced in $B$-hadron decay using the impact parameter
information of muons. The polarization is measured over
the kinematic range $4 |
Saturday, April 16, 2005 4:54PM - 5:06PM |
E11.00007: Subleading Shape Functions in Inclusive B Decays Gil Paz Inclusive decays of $B$ mesons into final states containing light particles, such as $\bar B \rightarrow X_u l\bar \nu$ and \bar B \rightarrow X_s \gamma$ play a prominent role in the extraction of |Vub|. Recently, significant progress has been made by systematically incorporating higher-order perturbative corrections. This leaves power corrections to the heavy-quark limit as the principal source of theoretical uncertainties. In this work, we use Soft Collinear Effective theory (SCET) to perform a systematic study of such power-suppressed effects. At tree level, the results can be expressed in terms of a set of subleading shape functions defined via the Fourier transforms of forward matrix elementsm of bi-local light-cone operators in heavy-quark effective theory. We also identify a new contribution arising from four-quark operators, which was not considered previously. We show that, when shape functions appearing in process- independent combinations are combined into single functions, then a total of three subleading shape functions are required to describe arbitrary current-induced decay distributions of B mesons into light final-state particles. While subleading shape-function effects had been studied in the past, our results do not agree with some of these studies. We present analytical expressions for a variety of distributions in $\bar B \rightarrow X_u l\bar \nu$ which can be used directly for the analysis of experimental data. We also give a formula for the triple differential rate, which allows for arbitrary cuts on kinematic variables. A numerical analysis of the decay distributions suggests that power corrections are small, with the possible exception of the endpoint region of the charged-lepton energy spectrum. [Preview Abstract] |
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