Beam–target helicity asymmetry E in K+Σ− photoproduction on the neutron
Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics
We report a measurement of a beam–target double-polarisation observable (E) for the γ→n→(p)→K+Σ−(p) reaction. The data were obtained impinging the circularly-polarised energy-tagged photon beam of Hall B at Jefferson Lab on a longitudinally-polarised frozen-spin hydrogen deuteride (HD) nuclear target. The E observable for an effective neutron target was determined for centre-of-mass energies 1.70≤W≤2.30 GeV, with reaction products detected over a wide angular acceptance by the CLAS spectrometer. These new double-polarisation data give unique constraints on the strange decays of excited neutron states. Inclusion of the new data within the Bonn-Gatchina theoretical model results in significant changes for the extracted photocouplings of a number of established nucleon resonances. Possible improvements in the PWA description of the experimental data with additional “missing” resonance states, including the N(2120)3/2− resonance, are also quantified.
Zachariou, N., Watts, D., Fleming, J., Sarantsev, A., Nikonov, V., D'Angelo, A., Bashkanov, M., Hanretty, C., Kageya, T., Klein, F., Lowry, M., Lu, H., Sandorfi, A., Wei, X., Zonta, I., Adhikari, K., Adhikari, S., Amaryan, M., Angelini, G., Asryan, G., Atac, H., Barion, L., Bass, C., Battaglieri, M., Bedlinskiy, I., Benmokhtar, F., Bianconi, A., Biselli, A., Bossù, F., Boiarinov, S., & Briscoe, W. (2020). Beam–target helicity asymmetry E in K+Σ− photoproduction on the neutron. Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics, 808. https://doi.org/10.1016/j.physletb.2020.135662