Baryons as relativistic three-quark bound states

Abstract

We review the spectrum and electromagnetic properties of baryons described as relativistic three-quark bound states within QCD. The composite nature of baryons results in a rich excitation spectrum, whilst leading to highly non-trivial structural properties explored by the coupling to external (electromagnetic and other) currents. Both present many unsolved problems despite decades of experimental and theoretical research. We discuss the progress in these fields from a theoretical perspective, focusing on nonperturbative QCD as encoded in the functional approach via Dyson-Schwinger and Bethe-Salpeter equations. We give a systematic overview as to how results are obtained in this framework and explain technical connections to lattice QCD. We also discuss the mutual relations to the quark model, which still serves as a reference to distinguish 'expected' from 'unexpected' physics. We confront recent results on the spectrum of non-strange and strange baryons, their form factors and the issues of two-photon processes and Compton scattering determined in the Dyson-Schwinger framework with those of lattice QCD and the available experimental data. The general aim is to identify the underlying physical mechanisms behind the plethora of observable phenomena in terms of the underlying quark and gluon degrees of freedom.

140 pages, 52 figures, 3 tables. Invited review for Progress in Particle and Nuclear Physics. Changes from v1: minor additions, corrected typos and added references; brief discussion on light-front and holographic QCD in Sec. 3.2; updated Figs. 3.22-3.23 and corresponding discussion

References in corpus (144)

• Big-Bang Nucleosynthesis
• Exact evolution equation for the effective potential
• Heavy quarkonium: progress, puzzles, and opportunities
• Ab-initio Determination of Light Hadron Masses
• A refinement of the Gribov-Zwanziger approach in the Landau gauge: infrared propagators in harmony with the lattice results
• Gluon and ghost propagators in the Landau gauge: Deriving lattice results from Schwinger-Dyson equations
• Infrared Properties of QCD from Dyson-Schwinger equations
• Lattice gluodynamics computation of Landau-gauge Green's functions in the deep infrared
• Ab initio calculation of the neutron-proton mass difference
• Unitary Isobar Model - MAID2007
• High-precision determination of the electric and magnetic form factors of the proton
• Nucleon Electromagnetic Form Factors
• Pinch Technique: Theory and Applications
• A novel quark-field creation operator construction for hadronic physics in lattice QCD
• Electromagnetic excitation of the Delta(1232)-resonance
• Global analysis of proton elastic form factor data with two-photon exchange corrections
• Chiral symmetry breaking in continuum QCD
• The Proton Radius Puzzle
• Sketching the Bethe-Salpeter kernel
• Four-Quark Hadrons: an Updated Review
• Bridging a gap between continuum-QCD and ab initio predictions of hadron observables
• A study of quasi-elastic muon neutrino and antineutrino scattering in the NOMAD experiment
• Dynamical coupled-channel model of meson production reactions in the nucleon resonance region
• Nucleon electromagnetic form factors
• Towards a data-driven analysis of hadronic light-by-light scattering
• Constraints on the IR behavior of the ghost propagator in Yang-Mills theories
• Lattice QCD Evidence that the Lambda(1405) Resonance is an Antikaon-Nucleon Molecule
• Light hadron spectroscopy using domain wall valence quarks on an Asqtad sea
• Dressed-quark anomalous magnetic moments
• The Flavor Structure of the Excited Baryon Spectra from Lattice QCD
• The quark-gluon vertex in Landau gauge QCD: Its role in dynamical chiral symmetry breaking and quark confinement
• Resonances in coupled πK,ηK scattering from quantum chromodynamics
• Baryon spectrum with $N_f=2+1+1$ twisted mass fermions
• Light Hadron Masses from Lattice QCD
• Three-point vertices in Landau-gauge Yang-Mills theory
• Nonperturbative determination of the QCD potential at O(1/m)
• Resonances in coupled $\pi K,\eta K$ scattering from lattice QCD
• Two-Photon Physics in Hadronic Processes
• Propagators and phase structure of Nf=2 and Nf=2+1 QCD
• Flavor decomposition of the elastic nucleon electromagnetic form factors
• The size of the proton - closing in on the radius puzzle
• Using effective field theory to analyse low-energy Compton scattering data from protons and light nuclei
• Nucleon electromagnetic form factors from the covariant Faddeev equation
• Baryons in AdS/QCD
• Leading SU(3)-breaking corrections to the baryon magnetic moments in Chiral Perturbation Theory
• Uniqueness of infrared asymptotics in Landau gauge Yang-Mills theory
• Pion form factor from a contact interaction
• Nucleon isovector couplings from $N_f=2$ lattice QCD
• Dynamical Coupled-Channel Model of $\pi N$ Scattering in the W $\le$ 2 GeV Nucleon Resonance Region
• Measurement of the two-photon exchange contribution to the elastic $e^{\pm }p$ scattering cross sections at the VEPP-3 storage ring
• Proton polarisability contribution to the Lamb shift in muonic hydrogen at fourth order in chiral perturbation theory
• Spin-dependent potentials from lattice QCD
• Masses of ground and excited-state hadrons
• Two- and three-point Green's functions in two-dimensional Landau-gauge Yang-Mills theory
• Mixing of scalar tetraquark and quarkonia states in a chiral approach
• Timelike pion form factor in lattice QCD
• Perspective on rainbow-ladder truncation
• Baryon Spectrum from Superconformal Quantum Mechanics and its Light-Front Holographic Embedding
• Light baryon masses with dynamical twisted mass fermions
• Towards a resolution of the proton form factor problem: new electron and positron scattering data
• Nucleon electromagnetic form factors from lattice QCD using a nearly physical pion mass
• Anomalous magnetic moment of the muon in a dispersive approach
• Superconformal Baryon-Meson Symmetry and Light-Front Holographic QCD
• eta-photoproduction in the resonance energy region
• The nucleon electromagnetic form factors from Lattice QCD
• Beyond the rainbow: effects from pion back-coupling
• Hadronic unquenching effects in the quark propagator
• The quark-gluon vertex in Landau gauge bound-state studies
• Spectra of heavy quarkonia in a Bethe-Salpeter-equation approach
• Future Prospects for Hadron Physics at PANDA
• Effective confining potentials for QCD
• Measurement of the Rate of Muon Capture in Hydrogen Gas and Determination of the Proton's Pseudoscalar Coupling $g_P$
• Spectra of heavy mesons in the Bethe-Salpeter approach
• Two-photon exchange in dispersion approach
• Nucleon Electromagnetic Form Factors in the Timelike Region
• A pure S-wave covariant model for the nucleon
• A Dyson-Schwinger study of the four-gluon vertex
• On light baryons and their excitations
• Extraction and Interpretation of gamma N --> Delta Form Factors within a Dynamical Model
• Role of diquark correlations and the pion cloud in nucleon elastic form factors
• Extracting Nucleon Magnetic Moments and Electric Polarizabilities from Lattice QCD in Background Electric Fields
• A new method for determining the quark-gluon vertex
• Two-photon exchange in elastic electron-proton scattering : QCD factorization approach
• The reaction pi+ p --> K+ Sigma+ in a unitary coupled-channels model
• Nucleon structure with two flavors of dynamical domain-wall fermions
• Quark Confinement: The Hard Problem of Hadron Physics
• Flavour symmetry breaking and meson masses
• Hadron Spectroscopy with Dynamical Chirally Improved Fermions
• Light baryon magnetic moments and N -> Delta gamma transition in a Lorentz covariant chiral quark approach
• Electromagnetic structure of the lowest-lying decuplet resonances in covariant chiral perturbation theory
• Contribution of spin 1/2 and 3/2 resonances to two-photon exchange effects in elastic electron-proton scattering
• D-state effects in the electromagnetic N-Delta transition
• A Covariant model for the nucleon and the $\Delta$
• First Measurements of Timelike Form Factors of the Hyperons, Lambda0, Sigma0, Sigma+, Xi0, Xi-, and Omega-, and Evidence of Diquark Correlations
• Exciting flavored bound states
• Reduction of the proton radius discrepancy by 3 sigma
• Electroexcitation of the Roper resonance in the relativistic quark models
• Nucleon resonances in AdS/QCD
• Quark-gluon vertex dressing and meson masses beyond ladder-rainbow truncation
• Chiral extrapolation of nucleon magnetic form factors
• Neutron electric polarizability from unquenched lattice QCD using the background field approach
• Time- and Spacelike Nucleon Electromagnetic Form Factors beyond Relativistic Constituent Quark Models
• Perturbative QCD predictions for two-photon exchange
• Nucleon to Delta transition form factors with $N_F=2+1$ domain wall fermions
• Mass spectra and Regge trajectories of light mesons in the Bethe-Salpeter approach
• A novel analysis method for excited states in lattice QCD - the nucleon case
• Delta and Omega electromagnetic form factors in a Dyson-Schwinger/Bethe-Salpeter approach
• U_A(1) anomaly and eta' mass from an infrared singular quark-gluon vertex
• Lattice baryon spectroscopy with multi-particle interpolators
• Light-cone Distribution Amplitudes of the Nucleon and Negative Parity Nucleon Resonances from Lattice QCD
• Electromagnetic Form Factors and Charge Densities From Hadrons to Nuclei
• Hadron structure at low Q^2
• A covariant study of tensor mesons
• Nucleon resonances in πN scattering up to energies \sqrt(s) < 2.0 GeV
• Nucleon Form Factors - A Jefferson Lab Perspective
• Two-photon exchange corrections in elastic muon-proton scattering
• Lepton flavor at the electroweak scale: A complete A4 model
• Electroproduction of the Roper resonance on the proton: the role of the three-quark core and the molecular N-sigma component
• Nucleon Compton scattering in the Dyson-Schwinger approach
• Octet and Decuplet masses: a covariant three-body Faddeev calculation
• Nucleon Form Factors of the Isovector Axial-Vector Current: Situation of Experiments and Theory
• Delta-baryon mass in a covariant Faddeev approach
• Large-$N_c$ relations for the electromagnetic N to Delta(1232) transition
• First Lattice Study of the $N$-$P_{11}(1440)$ Transition Form Factors
• Dispersive contributions to $e^{+}p/e^{-}p$ cross section ratio in forward regime
• Rho-meson, Bethe-Salpeter equation, and the far infrared
• Linear meson and baryon trajectories in AdS/QCD
• Solving Bethe-Salpeter scattering state equation in Minkowski space
• Axial charges of octet and decuplet baryons
• The role of momentum dependent dressing functions and vector meson dominance in hadronic light-by-light contributions to the muon g-2
• Examining the Analytic Structure of Green's Functions: Massive Parallel Complex Integration using GPUs
• Chiral symmetry and pi-pi scattering in the Covariant Spectator Theory
• Nuclear Reactions from Lattice QCD
• Structure of meson-baryon interaction vertices
• The neutron negative central charge density: an inclusive-exclusive connection
• SU(3)-flavour breaking in octet baryon masses and axial couplings
• Electromagnetic Decay of the ${\Sigma }^0(1385)$ to $\Lambda \gamma$
• Determination of the strange nucleon form factors
• Invariant Amplitudes for Pion Electroproduction
• Lattice Calculations of Nucleon Electromagnetic Form Factors at Large Momentum Transfer
• Diquark bound states with a completely crossed ladder truncation
• Electromagnetic baryon form factors in the Poincare-covariant Faddeev approach
• On kinematical constraints in the hadrogenesis conjecture for the baryon resonance spectrum
• Nonperturbative light-front methods

Cited by in corpus (56)

• Spectrum of light- and heavy-baryons
• Natural constraints on the gluon-quark vertex
• Empirical Consequences of Emergent Mass
• On light baryons and their excitations
• Emergent Hadron Mass in Strong Dynamics
• Hamiltonian effective field theory study of the ${\mathbf{N}}^{\ast }(1440)$ resonance in lattice QCD
• Elastic electromagnetic form factors of vector mesons
• Light Baryon Spectroscopy
• Non-perturbative aspects of Euclidean Yang-Mills theories in linear covariant gauges: Nielsen identities and a BRST invariant two-point correlation function
• Ghost dynamics in the soft gluon limit
• Parity partners in the baryon resonance spectrum
• Emergence of pion parton distributions
• Dissecting nucleon transition electromagnetic form factors
• Measures of pion and kaon structure from generalised parton distributions
• Strong and radiative decays of excited vector mesons and predictions for a new $\varphi (1930)$ resonance
• Parton distributions of light quarks and antiquarks in the proton
• Pion and Kaon box contribution to $a_{\mu }^{\text{HLbL}}$
• The $\sigma$-meson: four-quark vs. two-quark components and decay width in a Bethe-Salpeter approach
• The soft-gluon limit and the infrared enhancement of the quark-gluon vertex
• Pseudo-scalar mesons: light front wave functions, GPDs and PDFs
• Form Factors of the Nucleon Axial Current
• ${\gamma }^{\ast }N\to N^{\ast }(1520)$ form factors in the timelike regime
• Comparison of two Minkowski-space approaches to heavy quarkonia
• Quark propagator in Minkowski space
• Covariant spectator theory of quark-antiquark bound states: Mass spectra and vertex functions of heavy and heavy-light mesons
• More about the light baryon spectrum
• Phase structure of 2+1-flavour QCD and the magnetic equation of state
• Exact Solutions to the Fermion Propagator Schwinger-Dyson Equation in Minkowski space with on-shell Renormalization for Quenched QED
• Quark anomalous magnetic moment and its effects on the $\rho$ meson properties
• Contact interaction analysis of octet baryon axialvector and pseudoscalar form factors
• Distribution amplitudes of light diquarks
• Quark mass function from a one-gluon-exchange-type interaction in Minkowski space
• Photo- and electro-production of narrow exotic states: from light quarks to charm and up to bottom
• Unpolarized generalized parton distributions of light and heavy vector mesons
• Three-boson bound states in Minkowski space with contact interactions
• Models and Potentials in Hadron Spectroscopy
• Dynamical Chiral Symmetry Breaking in Quantum Chromo Dynamics: Delicate and Intricate
• Center phase transition from matter propagators in (scalar) QCD
• Sum rule for the partial decay rates of bottom hadrons based on the dynamical supersymmetry of the $\bar{s}$ quark and the $ud$ diquark
• The rainbow modified-ladder approximation and degenerate pion
• Gluon correlation functions from lattice quantum chromodynamics
• Pion inspired by QCD: Nakanishi and Light-Front Integral Representations
• Double non-perturbative gluon exchange: an update on the soft Pomeron contribution to pp scattering
• The Equal-Time Quark Propagator in Coulomb Gauge
• The chiral limit of a fermion-scalar $(1/2{)}^{+}$ system in covariant gauges
• Application of the Covariant Spectator Theory to the study of heavy and heavy-light mesons
• The gap equations of background field invariant Refined Gribov-Zwanziger action proposals and the deconfinement transition
• Two-flavor hybrid stars with the Dyson-Schwinger quark model
• Renormalized Schwinger-Dyson functional
• Baryons with functional methods
• Two photon transition form factors of neutral pseudoscalar mesons
• Quark-photon vertex from lattice QCD in Landau gauge
• Regarding the distribution of glue in the pion
• Pion electromagnetic form factor with Minkowskian dynamics
• Excited light baryons from quark-gluon-level calculations
• Pion GPDs: A path toward phenomenology