Nucleon mass: trace anomaly and $\sigma$-terms

Abstract

We give a pedagogical introduction to the origin of the mass of the nucleon. We first review the trace anomaly of the energy-momentum tensor, which generates most of the nucleon mass via the gluon fields and thus contributes even in the case of vanishing quark masses. We then discuss the contributions to the nucleon mass that do originate from the Higgs mechanism via the quark masses, reviewing the current status of nucleon $\sigma$-terms that encode the corresponding matrix elements.

12 pages, 1 figure, version to be published in the Encyclopedia of Particle Physics

References in corpus (29)

• Glueballs, Hybrids, Multiquarks. Experimental facts versus QCD inspired concepts
• Ab initio calculation of the neutron-proton mass difference
• Extended Partial-Wave Analysis of piN Scattering Data
• Hadronic Uncertainties in the Elastic Scattering of Supersymmetric Dark Matter
• Baryon spectrum with $N_f=2+1+1$ twisted mass fermions
• Lattice QCD at the physical point: light quark masses
• Charmed and light pseudoscalar meson decay constants from four-flavor lattice QCD with physical light quarks
• Precision calculation of the pi^- deuteron scattering length and its impact on threshold pi-N scattering
• Improved limits for Higgs-portal dark matter from LHC searches
• Analyses of pion-nucleon elastic scattering amplitudes up to $O(p^4)$ in extended-on-mass-shell subtraction scheme
• Chiral extrapolations of baryon masses for unquenched three-flavor lattice simulations
• On the pi pi continuum in the nucleon form factors and the proton radius puzzle
• Hadronic atoms in QCD + QED
• Roy-Steiner equations for pion-nucleon scattering
• Dispersive analysis of the scalar form factor of the nucleon
• Improved predictions for $\mu \to e$ conversion in nuclei and Higgs-induced lepton flavor violation
• Pionic deuterium
• Aspects of meson-baryon scattering in three- and two-flavor chiral perturbation theory
• Isospin breaking in the pion-nucleon scattering lengths
• Hadronic shift in pionic hydrogen
• The pion-nucleon $\sigma$ term from pionic atoms
• Dispersive and absorptive corrections to the pion-deuteron scattering length
• On the role of isospin violation in the pion-nucleon $\sigma$-term
• Nucleon resonance parameters from Roy-Steiner equations
• Role of the Delta(1232) in pion-deuteron scattering at threshold within chiral effective field theory
• Next-to-leading order scalar contributions to $\mu \to e$ conversion
• Dispersive Determination of Nucleon Gravitational Form Factors
• Low-energy constants in the chiral Lagrangian with baryon octet and decuplet fields from Lattice QCD data on CLS ensembles
• Test of isospin symmetry via low energy ${}^1$H(${\pi }^{-}$,${\pi }^o$)$n$ charge exchange