Extraction of resonances from meson-nucleon reactions

Journal Article · Sun Feb 15 04:00:00 EST 2009 · Physical Review. C, Nuclear Physics

DOI:https://doi.org/10.1103/PHYSREVC.79.025205· OSTI ID:21199578

Suzuki, N; Sato, T; Lee, T.-S. H. ^[1]

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1. Excited Baryon Analysis Center (EBAC), Thomas Jefferson National Accelerator Facility, Newport News, Virginia 23606 (United States) and Department of Physics, Osaka University, Toyonaka, Osaka 560-0043 (Japan)

We present a pedagogical study of the commonly employed speed-plot (SP) and time-delay (TD) methods for extracting the resonance parameters from the data of two-particle coupled-channels reactions. Within several exactly solvable models, it is found that these two methods find poles on different Riemann sheets and are not always valid. We then develop an analytic continuation method for extracting nucleon resonances within a dynamical coupled-channel formulation of {pi}N and {gamma}N reactions. The main focus of this paper is on resolving the complications from the coupling with the unstable {pi}{delta}, {rho}N, and {sigma}N channels, which decay into {pi}{pi}N states. By using the results from the considered exactly solvable models, explicit numerical procedures are presented and verified. As a first application of the developed analytic continuation method, we present the nucleon resonances in some partial waves extracted within a recently developed coupled-channels model of {pi}N reactions. The results from this realistic {pi}N model, which includes {pi}N, {eta}N, {pi}{delta}, {rho}N, and {sigma}N channels, also show that the simple pole parametrization of the resonant propagator using the poles extracted from SP and TD methods works poorly.

• OSTI ID: 21199578
• Journal Information: Physical Review. C, Nuclear Physics, Journal Name: Physical Review. C, Nuclear Physics Journal Issue: 2 Vol. 79; ISSN 0556-2813; ISSN PRVCAN
• Country of Publication: United States
• Language: English

Related Subjects

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS
COUPLED CHANNEL THEORY
COUPLING
DECAY
EXACT SOLUTIONS
EXTRACTION
GAMMA RADIATION
MESONS
NUCLEON REACTIONS
NUCLEONS
PARTIAL WAVES
PARTICLES
PION-NUCLEON INTERACTIONS
RESONANCE
RIEMANN SHEET
SIMULATION
TIME DELAY