Bulletin of the American Physical Society
2007 APS April Meeting
Volume 52, Number 3
Saturday–Tuesday, April 14–17, 2007; Jacksonville, Florida
Session H16: Hadronic Physics II |
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Sponsoring Units: DNP Chair: Reinhard Schumacher, Carnegie Mellon University Room: Hyatt Regency Jacksonville Riverfront City Terrace 12 |
Sunday, April 15, 2007 8:30AM - 8:42AM |
H16.00001: Baryon Resonance Form Factors at High Momentum Transfer. Paul Stoler Baryon resonance form factors can provide valuable information about the QCD structure of nucleons, especially when combined with information from other exclusive reactions such as high momentum transfer elastic scattering, real and virtual Compton scattering and meson electroproduction. Recently, several experiments at Jefferson Lab have measured form factors for the $\Delta(1232)$ and $S_{11}(1535)$ resonances for maximum $Q^2$ of greater than 7 GeV$^2$/c$^2$. The latest results of these experiments will be presented and the connections with other exclusive reactions such as elastic scattering form factors in terms of common nucleon structure within the framework of generalized parton distributions will be shown. [Preview Abstract] |
Sunday, April 15, 2007 8:42AM - 8:54AM |
H16.00002: Quark propagation and hadron formation in the nucleus Hayk Hakobyan, Will Brooks Preliminary results of CLAS Experiment 02-104 at Thomas Jefferson National Accelerator Facility will be presented. The main goal of the experiment was to investigate propagation of quarks through strongly interacting systems. Preliminary results will be presented from a series of measurements comparing hadron production from several nuclei (carbon, iron, and lead) in DIS kinematics to that from deuterium. The attenuation of pions and the broadening of their transverse momentum were measured as a function of $Q^2$, $\nu$, $p_{T}^{2}$ and $Z_h$, with very good statistical precision. Qualitativly new results on the electroproduction ``Cronin effect'' will be shown. These measurements are providing a greater understanding of the space-time characteristics of hadronization, and the medium-stimulated emission of gluons by energetic quarks. [Preview Abstract] |
Sunday, April 15, 2007 8:54AM - 9:06AM |
H16.00003: Simulation of semi-inclusive deep inelastic scattering from polarized $ep$ collisions at proposed EIC energies Joseph Seele, Edward Kinney A high luminosity electron-ion collider (EIC) is proposed which will allow the study of polarized electron-polarized proton collisions. One goal of this study is the determination of the polarized quark distributions of the proton. Several machine designs are under study that would operate with different luminosities and different collision energies. Using standard high-energy simulation programs, the semi-inclusive hadron yields and asymmetries from deep inelastic scattering have been obtained. In particular, these simulations were used to estimate the uncertainties which could be achieved in a determination of polarized quark distributions using the standard flavor-tagging techniques employed in fixed target experiments. While the focus is on the statistical uncertainties, limitations to reducing the systematic uncertainty will also be presented. Initial studies aimed at developing the hadronic detection requirements will be presented as well. [Preview Abstract] |
Sunday, April 15, 2007 9:06AM - 9:18AM |
H16.00004: Beam Spin Asymmetry Measurements from Deeply Virtual exclusive Meson Production Bo Zhao, Rita De Masi, Michel Garcon, Kyungseon Joo, Valeri Koubarovski, Paul Stoler, Maurizio Ungaro A DVCS experiment was run at Jefferson Lab during the spring of 2005 with the CLAS detector, using a 5.7 GeV longitudinally polarized electron beam impinging on a Hydrogen target. This experiment is being analyzed by the CLAS Collaboration to characterize the partonic properties of the nucleon in the framework of Generalized Parton Distributions(GPDs). We will report on the ongoing analysis to determine the Beam Spin Asymmetry for the pi0 and eta channels. [Preview Abstract] |
Sunday, April 15, 2007 9:18AM - 9:30AM |
H16.00005: Heavy Meson Mass Splittings Chandana Jayalath, Jose Goity The mass splittings in heavy mesons are studied in the framework of the heavy quark expansion. Within that framework, the masses of pseudoscalar and vector D- and B-mesons are analyzed to include effects due to the light quark masses $m_{u,d,s}$ as well as electromagnetic effects. The analysis is carried out to order $1/m_Q$ in the heavy quark mass expansion, and to first order in the light quark masses and the fine structure constant. The rather precise experimental knowledge of the heavy meson masses allows one to clearly separate the mentioned effects. For instance, one can identify and quantify the Coulomb and hyperfine electromagnetic effects. Careful analysis of the strong hyperfine splittings show that in order to have consistency with recent determinations of the heavy quark pole-mass ratio $m_c/m_b$ it is necessary to include a $1/m_Q^2$ correction. Predictions can be made for the mass splittings $(m_{B^{*+}}- m_{B^{+}})$ and $(m_{B^{*0}}- m_{B^{0}})$, which are not experimentally known. Finally, we compare our results for the mass shift effects due to the light quark masses and to electromagnetism with those in the light meson sector. [Preview Abstract] |
Sunday, April 15, 2007 9:30AM - 9:42AM |
H16.00006: Transverse Target Spin Asymmetry in exclusive vector meson production at HERMES Stephen Gliske, Wolfgang Lorenzon, Avetik Airapetian Measurements of the Transverse Target Spin Asymmetry, $A_{UT} (\phi)$, for hard exclusive electroproduction of $\rho^0$ and $\phi$ mesons at HERMES will be presented. To gain information about the general parton distribution function $E$, the transverse target spin asymmetry $A_{UT}^{\rho_L}(\phi)$ in the longitudinal cross section $\sigma_L(\gamma^*_Lp\rightarrow \rho^0_Lp\prime)$ needs to be extracted. Using the self-analyzing character of $\rho^{0}$ meson decay $A_{UT}^{\rho_L}(\phi)$ and $A_{UT}^{\rho_T}(\phi)$ will be presented separately. [Preview Abstract] |
Sunday, April 15, 2007 9:42AM - 9:54AM |
H16.00007: Gluons and Quarks Imprisoned by QCD Forces Carl Case Massless quarks and gluons with synchronized velocities can trigger chiral symmetry breaking. Countervailing color currents lead to total cancellation of the color electric fields. Dirac equation solutions: (a) indicate how chiral symmetry is broken; (b) explain how flavors arise; (c) illustrate how quarks and gluons acquire mass; (d) shed light on proton spin structure; and (e) provide a power law pattern for the quark masses. [Preview Abstract] |
Sunday, April 15, 2007 9:54AM - 10:06AM |
H16.00008: Spin Effects in Forward Pion Production Len Eun This talk summarizes STAR measurements of forward $\pi ^{0}$ meson production at $\sqrt s $= 200 and 62 GeV from polarized proton collisions at the Relativistic Heavy Ion Collider (RHIC). Measurements show that analyzing power (A$_{N})$ is an increasing function of x$_{F}$ at x$_{F} \quad >$ 0.3 and consistent with zero at x$_{F} \quad <$ 0. Contrary to theoretical predictions, A$_{N}$ does not decrease monotonically with increasing p$_{T}$. The unpolarized $\pi ^{0}$ cross-sections measured at $\eta $ = 3.3, 3.8 and 4.0 are consistent with next-to-leading order pQCD calculations. The Forward Pion Detector (FPD) was expanded to FPD$^{++}$ in 2005. The improved acceptance of FPD$^{++}$ combined with 6.8 pb$^{-1}$ integrated luminosity and 60{\%} average beam polarization of the RHIC run 2006 provides the necessary statistics to measure A$_{N}$ precisely as functions of x$_{F}$ and p$_{T}$, and measurements of other spin observables. A further expansion to Forward Meson Spectrometer has been carried out, which will provide complete electromagnetic calorimeter coverage for -1$<\eta <$+4 in conjunction with the existing STAR Endcap and Barrel calorimeters. This will allow for the discrimination between the Collins and Sivers effect as the origin of transverse single spin effect in the forward region. [Preview Abstract] |
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