Photoproduction of {eta} mesons within a coupled-channels K-matrix approach

Journal Article · Sun Dec 14 23:00:00 EST 2008 · Physical Review. C, Nuclear Physics

DOI:https://doi.org/10.1103/PHYSREVC.78.065201· OSTI ID:21199459

Shyam, R ^[1]; Scholten, O ^[2]

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1. Saha Institute of Nuclear Physics, Kolkata 700 064 (India)
2. Kernfysisch Versneller Instituut, University of Groningen, 9747 AA Groningen (Netherlands)

We investigate photoproduction of {eta} mesons off protons and neutrons within a coupled-channels effective-Lagrangian method that is based on the K-matrix approach. The two-body final channels included are {pi}N, {eta}N, {phi}N, {rho}N, {gamma}N, K{lambda}, and K{sigma}. Nonresonant meson-baryon interactions are included in the model via nucleon intermediate states in the s and u channels and meson exchanges in the t-channel amplitude and the u-channel resonances. The nucleon resonances S{sub 11}(1535), S{sub 11}(1650), S{sub 31}(1620), P{sub 11}(1440), P{sub 11}(1710), P{sub 13}(1720), P{sub 33}(1232), P{sub 33}(1600), D{sub 13}(1520), D{sub 13}(1700), and D{sub 33}(1700) are included explicitly in calculations. Our model describes simultaneously the available data as well on total and differential cross sections as on beam and target asymmetries. This holds for the {gamma}p{yields}{eta}p reaction for photon energies ranging from very close to threshold to up to 3 GeV. The polarization observables show strong sensitivity to resonances that otherwise contribute only weakly to the total cross section. It is found that the pronounced bumplike structure seen in the excitation function of the {gamma}n{yields}{eta}n cross section at {gamma} energies around 1 GeV can be explained by the interference effects of S{sub 11}, P{sub 11}, and P{sub 13} resonance contributions.

• OSTI ID: 21199459
• Journal Information: Physical Review. C, Nuclear Physics, Journal Name: Physical Review. C, Nuclear Physics Journal Issue: 6 Vol. 78; ISSN 0556-2813; ISSN PRVCAN
• Country of Publication: United States
• Language: English

Related Subjects

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS
BOSON-EXCHANGE MODELS
COUPLED CHANNEL THEORY
ETA MESONS
EXCITATION FUNCTIONS
GEV RANGE 01-10
INTERFERENCE
K MATRIX
LAGRANGIAN FUNCTION
MESON-BARYON INTERACTIONS
NEUTRONS
PHOTONS
PHOTOPRODUCTION
POLARIZATION
PROTONS
S CHANNEL
SENSITIVITY
T CHANNEL
TOTAL CROSS SECTIONS
TWO-BODY PROBLEM
U CHANNEL