Gauge-invariant theory of pion photoproduction with dressed hadrons

Journal Article · Wed Oct 01 04:00:00 EDT 1997 · Physical Review, C

DOI:https://doi.org/10.1103/PhysRevC.56.2041· OSTI ID:542714

Haberzettl, H ^[1]

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1. Center for Nuclear Studies, Department of Physics, The George Washington University, Washington, D.C. 20052 (United States)

Based on an effective field theory of hadrons in which quantum chromodynamics is assumed to provide the necessary bare cutoff functions, a gauge-invariant theory of pion photoproduction with fully dressed nucleons is developed. The formalism provides consistent dynamical descriptions of {pi}N{r_arrow}{pi}N scattering and {gamma}N{r_arrow}{pi}N production mechanisms in terms of nonlinear integral equations for fully dressed hadrons. Defining electromagnetic currents via the gauging of hadronic n-point Green{close_quote}s functions, dynamically detailed currents for dressed nucleons are introduced. The dressed hadron currents and the pion photoproduction current are explicitly shown to satisfy gauge invariance in a self-consistent manner. Approximations are discussed that make the nonlinear formalism manageable in practice and yet preserve gauge invariance. This is achieved by recasting the gauge conditions for all contributing interaction currents as continuity equations with {open_quotes}surface{close_quotes} terms for the individual particle legs coming into or going out of the hadronic interaction region. General procedures are given that approximate any type of (global) interaction current in a gauge-invariance-preserving manner as a sum of single-particle {open_quotes}surface{close_quotes} currents. It is argued that these prescriptions carry over to other reactions, irrespective of the number or type of contributing hadrons or hadronic systems. {copyright} {ital 1997} {ital The American Physical Society}

• OSTI ID: 542714
• Journal Information: Physical Review, C, Journal Name: Physical Review, C Journal Issue: 4 Vol. 56; ISSN PRVCAN; ISSN 0556-2813
• Country of Publication: United States
• Language: English

Related Subjects

66 PHYSICS
CONTINUITY EQUATIONS
GAUGE INVARIANCE
GREEN FUNCTION
HADRONS
INTEGRAL EQUATIONS
PHOTON-NUCLEON INTERACTIONS
PHOTOPRODUCTION
PIONS
QUANTUM CHROMODYNAMICS
SELF-CONSISTENT FIELD