The pentaquark + has been searched for via the π−p → K−X reaction with beam momenta of 1.92 and 2.01 GeV/c at J-PARC. A missing mass resolution of 2 MeV (FWHM) was achieved but no sharp peak structure was observed. The upper limits on the production cross section averaged over the scattering angle from 2◦ to 15◦ in the laboratory frame were found to be less than 0.28 μb/sr at the 90% confidence level for both the 1.92- and 2.01-GeV/c data. The systematic uncertainty of the upper limits was controlled within 10%. Constraints on the + decay width were also evaluated with a theoretical calculation using an effective Lagrangian. The present result implies that the width should be less than 0.36 and 1.9 MeV for the spin-parity of 1/2+ and 1/2−, respectively.
High-resolution search for the Theta+ pentaquark via a pion-induced reaction at J-PARC
BOTTA, Elena;MARCELLO, Simonetta;
2014-01-01
Abstract
The pentaquark + has been searched for via the π−p → K−X reaction with beam momenta of 1.92 and 2.01 GeV/c at J-PARC. A missing mass resolution of 2 MeV (FWHM) was achieved but no sharp peak structure was observed. The upper limits on the production cross section averaged over the scattering angle from 2◦ to 15◦ in the laboratory frame were found to be less than 0.28 μb/sr at the 90% confidence level for both the 1.92- and 2.01-GeV/c data. The systematic uncertainty of the upper limits was controlled within 10%. Constraints on the + decay width were also evaluated with a theoretical calculation using an effective Lagrangian. The present result implies that the width should be less than 0.36 and 1.9 MeV for the spin-parity of 1/2+ and 1/2−, respectively.File | Dimensione | Formato | |
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