Bulletin of the American Physical Society
2006 APS April Meeting
Saturday–Tuesday, April 22–25, 2006; Dallas, TX
Session B9: Hadronic Physics I |
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Sponsoring Units: DNP Chair: Paul Reimer, Argonne National Laboratory Room: Hyatt Regency Dallas Cumberland B |
Saturday, April 22, 2006 10:45AM - 10:57AM |
B9.00001: Bethe-Salpeter Study of Heavy-light Pseudoscalar and Vector Meson Masses Nicholas Souchlas, Pieter Maris, Peter Tandy A model based on the ladder-rainbow truncation of the Dyson-Schwinger equations of QCD is extended to heavy-light ground state mesons in the charm and bottom quark regions. The approach is fully covariant. Consistent dressing of the light quark propagator is included in the calculations. Results presented will include the $B$, $B^\star$, $D$ and $D^\star$ mesons. [Preview Abstract] |
Saturday, April 22, 2006 10:57AM - 11:09AM |
B9.00002: Thermal Time Scales in a Color Glass Condensate Vivek Parihar, Allan Widom, Yogi Srivastava In a model of relativistic heavy ion collisions wherein the unconfined quark-gluon plasma is condensed into glass, we derive the Vogel-Fulcher-Tammann cooling law. This law is well known to hold true in condensed matter glasses. The high energy plasma is initially created in a very hot negative temperature state and cools down to the Hagedorn glass temperature at an ever decreasing rate. The cooling rate is largely determined by the QCD string tension derived from hadronic Regge trajectories. The ultimately slow relaxation time is characteristic of a color glass condensate. [Preview Abstract] |
Saturday, April 22, 2006 11:09AM - 11:21AM |
B9.00003: Coherent $\phi$-meson photoproduction on deuteron Tsutomu Mibe, David Tedeschi, Stepan Stepanyan Coherent $\phi$-meson photoproduction on deuteron
is studied in a high-statistics photo-deuteron experiment at CLAS
with a tagged photon beam ($E_{\gamma}=$ 0.8 -- 3.6~GeV).
The reaction $\gamma d \rightarrow \phi d$ is identified in the
$K\bar{K}d$ final state.
Because of the iso-scalar target, exchange of iso-vector mesons
(e.g. $\pi$ exchange) are
not allowed. A comparison of cross sections with proton results
would reveal the iso-spin
structure of the production amplitudes.
The high luminosity and a wide acceptance of CLAS enable one to
measure the coherent $\phi$ photoproduction reaction at large
angles for the first time.
At large angles, the $\phi$-nucleon cross section ($\sigma_{\phi N}$)
can be investigated via a double scattering diagram.
Recently, LEPS measured $\sigma_{\phi N}$ from nuclear A-dependence.
The $\sigma_{\phi N}$ is large compared to the quark model
prediction.
A comparison of $\sigma_{\phi N}$ with the one from the A-dependence
is of great interest in connection with poss |
Saturday, April 22, 2006 11:21AM - 11:33AM |
B9.00004: Measurement of the Pion's Electric Form Factor Via Pion Electroproduction Tanja Horn A fundamental challenge in nuclear physics is the description of hadrons in terms of the constituents of the underlying theory of strong interactions. The simplest hadronic system is the pion, whose electromagnetic structure is determined by a single form factor ($F_\pi$). While $F_\pi$ can be calculated using perturbative QCD in the limit of very large values of four momentum transfer ($Q^2$), its calculation in the transition region from moderate to asymptotic values of $Q^2$ is model dependent. Assuming dominance of the pion exchange process, the value of $F_\pi$ can be extracted from the separated longitudinal response function. The $F_{\pi}2$-Collaboration measured the $^1H(e,e^\prime \pi^+)n$ reaction for two values of $Q^2$ (1.6 and 2.5 (GeV/c)$^2$) in Hall C at Jefferson Lab. This experiment will increase the dynamic range of precision data for which $F_{\pi}$ has been extracted to $Q^2$=2.5 (GeV/c)$^2$. The data may give an indication on the transition to the perturbative regime and will also help to constrain non-perturbative calculations of $F_{\pi}$ in a region where model predictions begin to diverge. [Preview Abstract] |
Saturday, April 22, 2006 11:33AM - 11:45AM |
B9.00005: Overview of the Hypernuclear Spectroscopy Experiment E01-011 at Jefferson Lab. Victor M. Rodriguez Experiment E01-011, ``Spectroscopic Study of $\Lambda $ Hypernuclei up to Medium-Heavy Mass Region Through the (e, e' K$^{+})$ Reaction'', (HKS), was successfully completed during a 2005 summer run in Hall C at the Jefferson Laboratory. Data were taken using C12, Si28, Li6, Li7, and Be9 targets. The experimental geometry included a new High Resolution Kaon Spectrometer (HKS), and implemented a ``Tilt Method'' for the electron spectrometer in order to increase the yield and the signal to accidental ratio. The experiment was designed to achieve a hypernuclear energy resolution of $\sim $400 KeV with rates that match or exceed those obtained using mesonic reactions. These studies will help define the hyperon-nucleon interaction, and the $\Lambda $ effective mass in nuclear media. [Preview Abstract] |
Saturday, April 22, 2006 11:45AM - 11:57AM |
B9.00006: Excitation Spectra of $\Lambda $ Hypernuclei using the (e,e'K$^{+})$ Reaction Leon Cole The JLAB HKS experiment was designed to take full advantage of the (e,e'K$^{+})$ reaction and the new High Resolution Kaon Spectrometer. The expected results will provide $\Lambda $ hypernuclear spectra with the best energy resolution ever achieved. This energy resolution of $\sim $ 400 keV (FWHM) will yield knowledge on the single-particle behavior of $\Lambda $ hyperon in a nuclear medium and allow precise studies of the effective $\Lambda $ -N interaction. This presentation will showcase the preliminary results of the excitation spectra from the $^{28}$Si, $^{7}$Li, and $^{12}$C targets. [Preview Abstract] |
Saturday, April 22, 2006 11:57AM - 12:09PM |
B9.00007: Optical Calibration For Jefferson Lab HKS Spectrometer Lullin Yuan Jefferson Lab HKS experiment aims at obtaining high resolution hypernuclear spectroscopy by $(e,e'K)$ reaction. The calibration of the HKS spectrometer is crucial in order to obtain the proposed missing mass resolution. This calibration procedure is complicated due to the use of a zero degree on-target splitter magnet. We have developed a high precision optical calibration method, making use of the known masses of $\Lambda$,$\Sigma^0$ hyperons produced from hydrogen in CH$_2$ target and the narrow width of $^{12}_\Lambda$B hypernuclear ground state from $^{12}$C target. To deal with the high accidental background, we have implemented the Expectation-Maximization parameter estimation method. In this talk, the procedure of the calibration will be described and the preliminary results of the calibration will be presented. [Preview Abstract] |
Saturday, April 22, 2006 12:09PM - 12:21PM |
B9.00008: Searching for $\Phi(1860)^{- -}$ pentaquark state in photo-induced reactions using the CLAS detector J\"{o}rn Langheinrich, Hovanes Egiyan By launching the eg3 experiment the CLAS collaboration joined the worldwide efforts to search the $\Phi(1860)^{- -}$ state, which is predicted to be one of the S=-2 states in the pentaquark anti-decuplet. Evidence for this state has been found by the NA49 experiment but couldn't be confirmed by any other group so far. The eg3 experiment exploits the fact that the state - if present - decays by two subsequent weak interactions which allows us to cut on the extremely narrow invariant masses of the intermediate states as well as on the well separated decay vertices. The reconstruction of S=-2 states from its decay products is a new analysis technique for CLAS, thus pushing the hardware and software to their limits. Data taking and calibration are now completed and the intermediate states $\Lambda$ and $\Xi^-$ have been identified. The focus of the ongoing analysis is the search for the $\Phi(1860)^{- -}$ as well as for excited $\Xi$ states. [Preview Abstract] |
Saturday, April 22, 2006 12:21PM - 12:33PM |
B9.00009: Search for the $\Theta ^{+}$ Pentaquark with Photoproduction off Deuterium at CLAS Ken Hicks The g10 experiment at Jefferson Lab is a high-statistics measurement of photoproduction from a deuterium target with photon energies between 1.0-3.0 GeV. Two independent data sets were obtained, one at 80{\%} of the maximum magnetic field of the CLAS detector and one at 60{\%} of the maxiumum, each with a luminosity of order 30 pb$^{-1}$. For the final state pK$^{-}$K$^{+}$n the upper limit for the elementary production of the $\Theta ^{+}$ from the neutron is estimated using a model for final state interactions (FSI). This model and the estimated upper limit of the elementary cross section will be presented. In addition, production into the $\Lambda \Theta ^{+}$ final has been investigated, and cross section upper limits will be presented. The high statistics of the g10 experiment are placing significant constraints on the question of whether narrow pentaquark resonances can exist. [Preview Abstract] |
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