We report measurements of pi(+) and pi(0) meson photoproduction from longitudinally spin-polarised protons by an energy tagged (0.73-2.3 GeV) and linearly polarised photon beam. A close to complete solid angle coverage for the reaction products was provided by the CEBAF Large Acceptance Spectrometer at Jefferson Laboratory. The double-polarisation observable G is extracted from Maximum Likelihood fits to the data, enabling the first accurate determination for the reaction (gamma) over right arrow(rho) over right arrow -> pi(+)n, while also significantly extending the kinematic coverage for (gamma) over right arrow(rho) over right arrow -> pi(0)p. This large data set provides an important constraint on the properties and spectrum of excited nucleon states decaying to N pi in the mass range from 1.4 to 2.2 GeV, as well as for background (non-resonant) photoproduction processes. The considerable improvement achieved in the description of the observable G within the SAID and Bonn-Gatchina approaches after implementation of our data, illustrates that the partial-wave analyses now significantly extend the knowledge on N pi photoproduction amplitudes at W > 1.8 GeV. A partial-wave analysis using the new high-precision data set has a large impact on the extracted properties of high-spin nucleon excited states. (C) 2021 The Author. Published by Elsevier B.V.
Zachariou, N., Watts, D.p., Mcandrew, J., Zana, L., Bashkanov, M., Strakovsky, I.i., et al. (2021). Double polarisation observable G for single pion photoproduction from the proton. PHYSICS LETTERS. SECTION B, 817 [10.1016/j.physletb.2021.136304].
Double polarisation observable G for single pion photoproduction from the proton
D'Angelo A.Membro del Collaboration Group
;Lanza L.;Rizzo A.Membro del Collaboration Group
;
2021-06-10
Abstract
We report measurements of pi(+) and pi(0) meson photoproduction from longitudinally spin-polarised protons by an energy tagged (0.73-2.3 GeV) and linearly polarised photon beam. A close to complete solid angle coverage for the reaction products was provided by the CEBAF Large Acceptance Spectrometer at Jefferson Laboratory. The double-polarisation observable G is extracted from Maximum Likelihood fits to the data, enabling the first accurate determination for the reaction (gamma) over right arrow(rho) over right arrow -> pi(+)n, while also significantly extending the kinematic coverage for (gamma) over right arrow(rho) over right arrow -> pi(0)p. This large data set provides an important constraint on the properties and spectrum of excited nucleon states decaying to N pi in the mass range from 1.4 to 2.2 GeV, as well as for background (non-resonant) photoproduction processes. The considerable improvement achieved in the description of the observable G within the SAID and Bonn-Gatchina approaches after implementation of our data, illustrates that the partial-wave analyses now significantly extend the knowledge on N pi photoproduction amplitudes at W > 1.8 GeV. A partial-wave analysis using the new high-precision data set has a large impact on the extracted properties of high-spin nucleon excited states. (C) 2021 The Author. Published by Elsevier B.V.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
