skip to main content
OSTI.GOV title logo U.S. Department of Energy
Office of Scientific and Technical Information

Title: Search for Pentaquark States at CLAS

Abstract

After the initial claim of discovery of a possible pentaquark state named ?+(1540), many experiments reported positive and negative results opening a discussion about the existence of such exotic particle. Most of the experimental evidence was obtained from data previously collected for other purposes in many reaction channels and under very different kinematic conditions, so that direct comparison of the results of the different experiments are very difficult. New experiments with high resolution and high statistics are needed to solve the controversy. A comprehensive program to search for pentaquark in photoproduction reaction on proton and deuteron was undertaken at Jefferson Laboratory. These second generation experiments cover the few GeV region where most of the positive evidences were found, collecting more than 10 times the existing statistics. First experiments on proton and deuteron were completed showing no evidence for the ?+(1540) and setting upper limits on the production

Authors:
Publication Date:
Research Org.:
Thomas Jefferson Lab National Accelerator Facility
Sponsoring Org.:
USDOE
OSTI Identifier:
955724
Report Number(s):
JLAB-PHY-06-636; 7334877; DOE/ER/40150-4437
TRN: US1004734
DOE Contract Number:
AC05-060R23177
Resource Type:
Conference
Resource Relation:
Conference: Paper compiled for BEACH 2006
Country of Publication:
United States
Language:
English
Subject:
43 PARTICLE ACCELERATORS; CEBAF ACCELERATOR; DEUTERONS; OPENINGS; PHOTOPRODUCTION; PRODUCTION; PROTONS; RESOLUTION; STATISTICS; SPECTROMETERS

Citation Formats

De Vita, Raffaella. Search for Pentaquark States at CLAS. United States: N. p., 2007. Web.
De Vita, Raffaella. Search for Pentaquark States at CLAS. United States.
De Vita, Raffaella. Tue . "Search for Pentaquark States at CLAS". United States. doi:. https://www.osti.gov/servlets/purl/955724.
@article{osti_955724,
title = {Search for Pentaquark States at CLAS},
author = {De Vita, Raffaella},
abstractNote = {After the initial claim of discovery of a possible pentaquark state named ?+(1540), many experiments reported positive and negative results opening a discussion about the existence of such exotic particle. Most of the experimental evidence was obtained from data previously collected for other purposes in many reaction channels and under very different kinematic conditions, so that direct comparison of the results of the different experiments are very difficult. New experiments with high resolution and high statistics are needed to solve the controversy. A comprehensive program to search for pentaquark in photoproduction reaction on proton and deuteron was undertaken at Jefferson Laboratory. These second generation experiments cover the few GeV region where most of the positive evidences were found, collecting more than 10 times the existing statistics. First experiments on proton and deuteron were completed showing no evidence for the ?+(1540) and setting upper limits on the production},
doi = {},
journal = {},
number = ,
volume = ,
place = {United States},
year = {Tue May 01 00:00:00 EDT 2007},
month = {Tue May 01 00:00:00 EDT 2007}
}

Conference:
Other availability
Please see Document Availability for additional information on obtaining the full-text document. Library patrons may search WorldCat to identify libraries that hold this conference proceeding.

Save / Share:
  • We discuss the experimental program to search for baryon states with exotic flavor quantum numbers using CLAS at Jefferson Lab.
  • Baryon states beyond the usual qqq configuration has been searched for many years but no evidence was found until recently. The findings about a possible pentaquark state have driven a rebirth of the experimental activity in this field. A broad experimental program for the search for pentaquark states is presently in progress at Jefferson Lab with the CLAS detector. In this proceedings the results and perspective for experiments using proton targets are discussed.
  • No abstract prepared.
  • A search for photo-production of the Theta+(1540) pentaquark and its decay to pK0 was performed with the CLAS detector system at Jefferson Lab. In the exclusive channel gammad-->pK0sK-(p), about twenty-thousand events with a slow missing proton, pi+pi- decay of the neutral kaon, and photon energy between 1.6 and 3.6 GeV are fully reconstructed. Included are numerous hyperon and meson resonances, with their decays to pK- and K0K- respectively. To understand the possibility of a pentaquark signal amidst the backgrounds, a phenomenological isobar-inspired model of complex Breit-Wigner amplitudes and decay angular distributions for the resonances is fit to the data withmore » a maximum likelihood method. No pentaquark signal is found above the background. The upper limit on the total production cross section is measured to be consistent with other channels published by the collaboration, but systematic studies are still in progress.« less
  • Preliminary results of the analysis of the γ3He→ pΛΘ+ channel, a reaction not observed until now, are here summarized. The data have been obtained at Jefferson Lab with the CLAS detector for photon energies from threshold up to 1.55 GeV. The final state has been identified through the reconstruction of the decay modes Λ → pπ−, Θ+ → pK0, K0 → π+π−, as well as Θ+ → nK+. Three independent analysis techniques have been used.