Bulletin of the American Physical Society
2005 APS April Meeting
Saturday–Tuesday, April 16–19, 2005; Tampa, FL
Session Y12: Mini-symposium B: Pentaquarks and Other Exotics I |
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Sponsoring Units: DNP GFB Chair: Simon Capstick, Florida State University Room: Marriott Tampa Waterside Room 11 |
Tuesday, April 19, 2005 1:30PM - 2:06PM |
Y12.00001: Pentaquarks: Challenges and Pitfalls Invited Speaker: In this talk the current status of the pentaquark searches will be reviewed. Experimental results from different facilities in Japan, Russia, USA, Germany and elsewhere reporting the evidence for the existence of pentaquarks as well as reporting no evidence will be critically discussed. [Preview Abstract] |
Tuesday, April 19, 2005 2:06PM - 2:18PM |
Y12.00002: Evidence for the $\Theta^+$ from photoproduction on deuterium at SPring-8 Kenneth Hicks, T. Mibe The first evidence for an exotic baryon pentaquark, with strangeness S=+1 known as the $\Theta^+$, was published by the LEPS collaboration from data collected at the SPring-8 facility in Japan using a carbon target. A second experiment using a deuterium target has been analyzed, giving higher statistics than the carbon data. The new results, using two different detection topologies, show a peak near 1535 MeV. Details of the analysis and statistical interpretation of the results will be presented. [Preview Abstract] |
Tuesday, April 19, 2005 2:18PM - 2:30PM |
Y12.00003: Search for the $\Theta^+$ in the $\gamma d \to K^+ K^- p(n)$ reaction Tsutomu Mibe, D. Carman, K. Hicks, S. Stepanyan A signature indicating the existence of the S=+1 pentaquark state ($\Theta^+$) has been reported in more than ten experiments in a variety of reactions. On the other hand, there are a number of non-observations, mainly from the $e^+e^-$ collider experiments and other experiments at high-energy facilities. The main criticism for the existence of the $\Theta^+$ is the low statistical significance. None of the positive results show a high significance with sufficient statistics. A new experiment to search for the $\Theta^+$ in the photon-induced production on a deuteron has been pursued using the CLAS detector and the tagged-photon facility at Jefferson Laboratory. The integrated luminosity of the new data is about 10 times greater than the previously published CLAS data on a deuterium target. In this talk, an experimental overview and current analysis results for the $\gamma+d \rightarrow K^+K^-p (n)$ reaction will be presented. [Preview Abstract] |
Tuesday, April 19, 2005 2:30PM - 2:42PM |
Y12.00004: $\theta^{+}$ Search with Quasi-Free Photoproduction in Deuterium Nathan Baltzell, David Tedeschi The production of a possible exotic S=1 pentaquark off a neutron is being investigated in CLAS at Jefferson Lab. Using a tagged photon beam of energy up to 3.6 GeV incident on a 24 cm liquid deuterium target, the final state $pK^{0}_{s}K^{-}(p)$ is produced and identified by reconstructing the $K^{0}_{s}$ from $\pi^{+}\pi^{-}$ and spectator proton in missing mass. Evidence for the photoproduction of $\theta^{+}K^{-}$ and $\theta^{+}\rightarrow pK^{0}_{s}$ is investigated, and a comprehensive description of the current status of the analysis will be presented, including cuts, corrections, and backgrounds. [Preview Abstract] |
Tuesday, April 19, 2005 2:42PM - 2:54PM |
Y12.00005: Search for the Pentaquark Parnters: $\Sigma^0$, $N^0$ and $\Theta^{++}$ Yi Qiang Recent observations of a narrow, exotic, baryonic state, the $\Theta^+$, have generated great experimental and theoretical interests. The $\Theta^+$ has been predicted to be a 5-quark state which is a member of an antidecuplet of the flavor group $SU(3)_F$. If the $\Theta^+$ is confirmed, %It's very possilbe that $\Theta^+$ really exists, and if so the other members of this antidecuplet which are predicted to be narrow as well are also very likely to be observable. The Jefferson Lab experiment E04-012 focused on searching for two non-exotic antidecuplet parnters, $\Sigma^0$ and $N^0$, and one exotic isospin partner, $\Theta^ {++}$, in electro-production, $H(e,e^\prime K^-)X$ and $H(e,e^\prime K^+)X$, with $Q^2$ around 0.2 $(GeV/c)^2$ and $\theta_{\gamma K(\pi)} < 20^\circ$. Using the two Hall~A High Resolution Spectrometers allowed us to perform a high-resolution (FWHM=3.0~MeV) scan in the missing mass spectra. Data covering the range in missing mass of 1560-1860 MeV for the $\Sigma^0$, 1510-1900 MeV for the $N^0$ and 1460-1610 for the $\Theta^{++}$ have been obtained. The status and prospects will be discussed. [Preview Abstract] |
Tuesday, April 19, 2005 2:54PM - 3:06PM |
Y12.00006: The Search for Exotic Baryons at HERMES Wouter Deconinck, Wolfgang Lorenzon An experimental search for the $\Theta^{+}(1540)$ and $\Xi^{--}(1862) $ resonances was performed using the decay modes $pK_s$ and $\Xi^- \pi^-$, respectively. While evidence for a $\Theta^{+}(1540)$ with a statistical significance of $4\sigma$ is presented, no evidence for the $\Xi^{--}(1862)$ is found. The absence of a peak in the $\Xi^- \pi^-$ spectrum near 1862 MeV allows only to estimate an upper limit for quasi-real photoproduction of the $\Xi^{--}(1862)$. Systematic studies and future plans will be discussed as well. Among those is an attempt to use time-of-flight identification to probe low momentum $\Theta^{+}$ production. [Preview Abstract] |
Tuesday, April 19, 2005 3:06PM - 3:18PM |
Y12.00007: Search for Strange-Charmed Pentaquark States in the 1.96 TeV ppbar collision Scott Field Since the H1 collaboration reported D*-p bound state as a charmed pentaquark with a mass of $3.099 GeV/c^2$, there has been much interest in Heavy-Flavor pentaquark searches. Theorists have predicted both strong and weak decays of strange-charmed pentaquark states near the mass threshold of Ds+p. We report searches for the strange-charmed pentaquark states using 240 pb-1 of data collected by CDF II detector at the Fermilab. [Preview Abstract] |
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