Sigma Terms of Light-Quark Hadrons

Abstract

A calculation of the current-quark mass dependence of hadron masses can help in using observational data to place constraints on the variation of nature's fundamental parameters. A hadron's sigma-term is a measure of this dependence. The connection between a hadron's sigma-term and the Feynman-Hellmann theorem is illustrated with an explicit calculation for the pion using a rainbow-ladder truncation of the Dyson-Schwinger equations: in the vicinity of the chiral limit sigma_pi = m_pi/2. This truncation also provides a decent estimate of sigma_rho because the two dominant self-energy corrections to the rho-meson's mass largely cancel in their contribution to sigma_rho. The truncation is less accurate for the omega, however, because there is little to compete with an omega->rho+pi self-energy contribution that magnifies the value of sigma_omega by ~25%. A Poincare' covariant Faddeev equation, which describes baryons as composites of confined-quarks and -nonpointlike-diquarks, is solved to obtain the current-quark mass dependence of the masses of the nucleon and Delta, and thereby sigma_N and sigma_Delta. This "quark-core" piece is augmented by the "pion cloud" contribution, which is positive. The analysis yields sigma_N~60MeV and sigma_Delta~50MeV.

22 pages, reference list expanded

References in corpus (55)

• Dyson-Schwinger Equations and the Application to Hadronic Physics
• The fundamental constants and their variation: observational status and theoretical motivations
• The Infrared Behavior of QCD Green's Functions - Confinement, Dynamical Symmetry Breaking, and Hadrons as Relativistic Bound States
• A Search for Time Variation of the Fine Structure Constant
• Dyson-Schwinger Equations: Density, Temperature and Continuum Strong QCD
• Dyson-Schwinger equations: a tool for hadron physics
• pi- and K-meson Bethe-Salpeter Amplitudes
• Bethe-Salpeter Study of Vector Meson Masses and Decay Constants
• Pion mass and decay constant
• Goldstone Theorem and Diquark Confinement Beyond Rainbow-Ladder Approximation
• Non-perturbative Propagators, Running Coupling and Dynamical Quark Mass of Landau gauge QCD
• Analytic properties of the Landau gauge gluon and quark propagators
• Chiral expansion of baryon masses and $\sigma$-terms
• Dynamical Chiral Symmetry Breaking, Goldstone's Theorem and the Consistency of the Schwinger--Dyson and Bethe--Salpeter Equations
• Analysis of a quenched lattice-QCD dressed-quark propagator
• The Quark-Photon Vertex and the Pion Charge Radius
• Aspects and consequences of a dressed-quark-gluon vertex
• Electromagnetic Pion Form Factor and Neutral Pion Decay Width
• Survey of heavy-meson observables
• Ground-state Spectrum of Light-quark Mesons
• Limits on the temporal variation of the fine structure constant, quark masses and strong interaction from quasar absorption spectra and atomic clock experiments
• Valence-quark distributions in the pion
• Towards the infrared limit in SU(3) Landau gauge lattice gluodynamics
• Octet and Decuplet Baryons in a Covariant and Confining Diquark-Quark Model
• Nonperturbative structure of the quark-gluon vertex
• Propagators and running coupling from SU(2) lattice gauge theory
• Effective masses of diquarks
• Cosmological variation of deuteron binding energy, strong interaction and quark masses from big bang nucleosynthesis
• Electromagnetic Form Factors of Charged and Neutral Kaons
• Limits on Cosmological Variation of Strong Interaction and Quark Masses from Big Bang Nucleosynthesis, Cosmic, Laboratory and Oklo Data
• Diquark Masses from Lattice QCD
• Nucleon mass and pion loops
• Primordial nucleosynthesis with a varying fine structure constant: An improved estimate
• Sigma-term physics in the perturbative chiral quark model
• Quark-gluon vertex model and lattice-QCD data
• Infrared regularization for spin-1 fields
• Chiral Behaviour of the Rho Meson in Lattice QCD
• Neutron Moderation in the Oklo Natural Reactor and the Time Variation of alpha
• Limits on variations in fundamental constants from 21-cm and ultraviolet quasar absorption lines
• On Nucleon Electromagnetic Form Factors
• Modelling the quark propagator
• Chiral Extrapolations and the Covariant Small Scale Expansion
• Meson-loop contributions to the rho-omega mass splitting & rho charge radius
• QCD based quark description of pi-pi scattering up to the sigma and rho region
• Baryon masses, chiral extrapolations, and all that
• Pion Loop Contribution to Rho-Omega Mixing and Mass Splitting
• Quark propagator in Landau and Laplacian gauges with overlap fermions
• Nucleon electromagnetic form factors from lattice QCD
• On the complexion of pseudoscalar mesons
• Lattice QCD Calculations of the Sigma Commutator
• On Nucleon Electromagnetic Form Factors: A Pre'cis
• Extraction of the pion-nucleon sigma-term from the spectrum of exotic baryons
• Relativistic Three-Quark Bound States in Separable Two-Quark Approximation
• Pion-nucleon scattering and the nucleon sigma term in an extended sigma model
• Landau gauge Jacobian and BRST symmetry

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• Pion and Kaon Structure at the Electron-Ion Collider
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• Enhanced effects of variation of the fundamental constants in laser interferometers and application to dark matter detection
• Commentary on rainbow-ladder truncation for excited states and exotics
• Confinement contains condensates
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• Strange and nonstrange baryon spectra in the relativistic interacting quark-diquark model with a Gürsey and Radicati-inspired exchange interaction
• Dependence of nuclear binding on hadronic mass variation
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• Varying the light quark mass: impact on the nuclear force and Big Bang nucleosynthesis
• Empirical Consequences of Emergent Mass
• Improved limits on interactions of low-mass spin-0 dark matter from atomic clock spectroscopy
• Flavour symmetry breaking and meson masses
• Enhanced effect of quark mass variation in 229Th and limits from Oklo data
• On Th229 and time-dependent fundamental constants
• Effect of quark-mass variation on big bang nucleosynthesis
• Three Lectures on Hadron Physics
• Reflections upon the Emergence of Hadronic Mass
• Nucleon tensor charges and electric dipole moments
• Mind the gap
• Expanding the concept of in-hadron condensates
• Contact-interaction Faddeev equation and, inter alia, proton tensor charges
• Schwinger functions and light-quark bound states, and sigma terms
• Probing the quark-gluon interaction with hadrons
• Schwinger functions and light-quark bound states
• Exploring the light-quark interaction
• Chiral condensate in hadronic matter
• Variation of fundamental constants in space and time: theory and observations
• Relativistic quark-diquark model of baryons with a spin-isospin transition interaction
• Time Dependent Quark Masses and Big Bang Nucleosynthesis Revisited
• N* Structure and Strong QCD
• The impact of transverse Slavnov-Taylor identities on dynamical chiral symmetry breaking
• Strong Interaction Physics at the Luminosity Frontier with 22 GeV Electrons at Jefferson Lab
• Electric dipole moment of the rho-meson
• Current quark mass dependence of nucleon magnetic moments and radii
• Oklo reactors and implications for nuclear science
• Hadron Physics and Dyson-Schwinger Equations
• Evaluation of pion-nucleon sigma term in Dyson-Schwinger equation approach of QCD
• Constraints on the Variation of Physical Constants, Equivalence Principle Violation, and a Fifth Force from Atomic Experiments
• Hadron Structure using Continuum Schwinger Function Methods
• Looking into the matter of light-quark hadrons
• Meson-baryon sigma terms in QCD Sum Rules
• Searching for scalar field dark matter with hyperfine transitions in alkali atoms
• Partial wave analysis for the in-hadron condensate
• Confinement of Fermions in Tachyon Matter at Finite Temperature