High-Resolution Search for Pentaquark Partners in Hall A at Jefferson Lab

J.-O. Hansen
2006 AIP Conference Proceedings  
We have carried out a high-resolution search (σ = 1.5 MeV) for narrow exotic resonances (Γ < 10 MeV) in the mass range M ≈ 1500 − 1850 MeV in ep → e K + X, ep → e K − X and ep → e π + X electroproduction at forward angles (θ CM ≈ 6 − 7 • ). Such narrow resonances would be candidates for partner states of the speculative Θ + (1540) pentaquark. The experiment employed a 5 GeV CW electron beam incident on a liquid hydrogen target and two high-resolution magnetic spectrometers covering a total
more » ... vering a total center-of-mass solid angle of ΔΩ ≈ 30 − 40 msr. We do not observe a statistically significant signal in any of the three reaction channels. Upper limits on the production cross sections were determined to be between 3 and 16 nb/sr, depending on the channel and the assumed width of the state. In addition, precise electroproduction data of the Λ(1116), Σ(1193) and Λ(1520) resonances were obtained for calibration purposes.
doi:10.1063/1.2176497 fatcat:eamo3uhjsnfpzmzxxtxj5xxavm