Search for pentaquark partners [Theta]⁺⁺, [Sigma]⁰ and N⁰ in H (e,e'K [pi])) X reactions at Jefferson Lab Hall A

In 1997, D. Diakonov et al. using a soliton model predicted a SU(3)F flavor antide-cuplet of pentaquarks. The most striking prediction using this symmetry group is a narrow exotic state, E+(1540), which has quark component uuddg. If such a state is confirmed, other members of the antide cuplet could be expected to have sufficiently narrow widths to be observed as well. The Jefferson Laboratory experiment E04-012 focused on the search for EO and NO partner states in the missing mass spectra of the H(e,e'K+)X and H(e,e'ir+)X channels. In addition, if the 8+ has non-zero isospin then a hypothetical isospin partner, O++, 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, A(1116) and E(1193) production and provided a high sensitivity to narrow resonances. A precise measurement of the A(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.

Department dc:contributor.department

Massachusetts Institute of Technology. Dept. of Physics.

Grantor dc:publisher

Massachusetts Institute of Technology

Year dc:date.issued

2007

Author dc:creator

• Qiang, Yi, Ph. D. Massachusetts Institute of Technology

Advisor dc:contributor.advisor

• William Bertozzi and Shalev Gilad.

• Physics.

Statement dc:rights

• M.I.T. theses are protected by copyright. They may be viewed from this source for any purpose, but reproduction or distribution in any format is prohibited without written permission. See provided URL for inquiries about permission.

Licence dc:rights.uri

• http://dspace.mit.edu/handle/1721.1/7582

Language dc:language.iso

eng

Handle dc:identifier.uri

http://hdl.handle.net/1721.1/45410

OAI identifier oai:identifier

oai:dspace.mit.edu:1721.1/45410