Search for the Theta+ pentaquark in the gamma d -> Lambda n K+ reaction measured with CLAS

TL;DR

This study searched for the exotic Theta+ pentaquark in gamma d reactions using CLAS data but found no significant evidence, setting upper limits on its production cross section.

Contribution

First analysis of gamma d -> Lambda n K+ reaction with CLAS to search for Theta+ pentaquark, establishing upper limits on its production cross section.

Findings

No significant Theta+ signals observed.

Upper limit on total cross section between 5 and 25 nb.

Differential cross section upper limits reported.

Abstract

For the first time, the reaction gamma d -> Lambda n K+ has been analyzed in order to search for the exotic pentaquark baryon Theta+(1540). The data were taken at Jefferson Lab, using the Hall-B tagged-photon beam of energy between 0.8 and 3.6 GeV and the CEBAF Large Acceptance Spectrometer (CLAS). No statistically significant structures were observed in the nK+ invariant mass distribution. The upper limit on the gamma d -> Lambda Theta+ integrated cross section has been calculated and found to be between 5 and 25 nb, depending on the production model assumed. The upper limit on the differential cross section is also reported.