Physical Review C
Experimental results on the Sigma(+)(1189) hyperon transverse polarization in photoproduction on a hydrogen target using the CLAS detector at Jefferson Laboratory are presented. The Sigma(+)(1189) was reconstructed in the exclusive reaction gamma + p -> K-s(0) + Sigma(+)(1189) via the Sigma(+) -> p pi(0) decay mode. The K-s(0) was reconstructed in the invariant mass of two oppositely charged pions with the pi(0) identified in the missing mass of the detected p pi(+)pi(-) final state. Experimental data were collected in the photon energy range E-gamma = 1.0-3.5 GeV (root s range 1.66-2.73 GeV). We observe a large negative polarization of up to 95%. As the mechanism of transverse polarization of hyperons produced in unpolarized photoproduction experiments is still not well understood, these results will help to distinguish between different theoretical models on hyperon production and provide valuable information for the searches of missing baryon resonances.
Nepali, C. S., Amaryan, M., Adhikari, K. P., Aghasyan, M., Pereira, S. A., Baghdasaryan, H., ... & Biselli, A. S. (2013). Transverse polarization of Σ+(1189) in photoproduction on a hydrogen target in CLAS. Physical Review C, 87(4), 045206.