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Title Search for Pentaquark Partners Theta++, Sigma0 and N0 in H(e,e'K(pi))X Reactions at Jefferson Lab Hall A
Authors Yi Qiang
JLAB number JLAB-PHY-07-1008
LANL number (None)
Other number (None)
Document Type(s) (Thesis) 
Supported by U.S. Naval Research: No
Supported by Jefferson Lab LDRD Funding: No
A PHD thesis
Advisor(s) :
   William Bertozzi (MIT)
   Shalev Gilad (MIT)
Publication Abstract: In 1997, D. Diakonov et al. using a soliton model predicted a SU(3)F flavor antidecuplet of pentaquarks. The most striking prediction using this symmetry group is a narrow exotic state, Theta+(1540), which has quark component uudd(bar)s. If such a state is confirmed, other members of the antidecuplet could be expected to have sufficiently narrow widths to be observed as well. The Jefferson Laboratory experiment E04-012 focused on the search for Sigma0 and N0 partner states in the missing mass spectra of the H(e,e'K+)X and H(e,e'pi+)X channels. In addition, if the Theta+ has non-zero isospin then a hypothetical isospin partner, Theta++, might be expected in the H(e,e'K-)X channel; this was also investigated. The experiment was performed in Hall A at Jefferson Lab using a 5 GeV electron beam incident on a liquid hydrogen target. The two high resolution magnetic spectrometers were coupled to septum magnets to allow measurement of scattered electrons and outgoing hadrons at angles as small as 6 degrees. The missing mass resolution was determined to be 3.5 MeV/c2 FWHM using neutron, Lambda(1116) and Sigma(1193) production and provided a high sensitivity to narrow resonances. A precise measurement of the Lambda(1520) resonance has also been conducted for a cross-section comparison. As a result, no significant narrow resonances were observed in any of the three reaction channels being investigated. Based on this fact, a likelihood scan using the G. Feldman and R. Cousins method was performed. The analysis provided total cross section upper limits at 90% confidence level with no lower limits or always below background fluctuation.
Experiment Numbers: E04-012
Group: Hall A
Document: pdf
Accepted Manuscript:
Supporting Documents:
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