Title

Double polarisation observable G for single pion photoproduction from the proton

DOI

10.1016/j.physletb.2021.136304

Authors

N. Zachariou, University of York
D. P. Watts, University of York
J. McAndrew, The University of Edinburgh
L. Zana, Thomas Jefferson National Accelerator Facility
M. Bashkanov, University of York
I. I. Strakovsky, The George Washington University
R. Workman, The George Washington University
A. V. Sarantsev, Universität Bonn
V. Nikonov, Universität Bonn
K. P. Adhikari, Old Dominion University
S. Adhikari, Florida International University
M. J. Amaryan, Old Dominion University
G. Angelini, The George Washington University
W. R. Armstrong, Argonne National Laboratory
H. Atac, Temple University
N. A. Baltzell, Thomas Jefferson National Accelerator Facility
L. Barion, Istituto Nazionale di Fisica Nucleare, Sezione di Ferrara
M. Battaglieri, Thomas Jefferson National Accelerator Facility
I. Bedlinskiy, National Research Centre "Kurchatov Institute"
F. Benmokhtar, Duquesne University
A. Bianconi, Istituto Nazionale di Fisica Nucleare, Sezione di Pavia
A. S. Biselli, Fairfield University
M. Bondi, Istituto Nazionale di Fisica Nucleare, Sezione di Genova
F. Bossù, Universite Paris-Saclay
S. Boiarinov, Thomas Jefferson National Accelerator Facility
W. J. Briscoe, The George Washington University
W. K. Brooks, Universidad Técnica Federico Santa María
D. Bulumulla, Old Dominion University
D. S. Carman, Thomas Jefferson National Accelerator Facility
J. C. Carvajal, Florida International University
A. Celentano, Istituto Nazionale di Fisica Nucleare, Sezione di Genova

Document Type

Journal Article

Publication Date

6-10-2021

Publication Title

Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics

Volume

817

ISSN

3702693

Abstract

We report measurements of π+ and π0 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 γ→p→→π+n, while also significantly extending the kinematic coverage for γ→p→→π0p. This large data set provides an important constraint on the properties and spectrum of excited nucleon states decaying to Nπ 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 Nπ 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.

Open Access

Gold

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