nLab quark bag model



Quantum Field Theory

algebraic quantum field theory (perturbative, on curved spacetimes, homotopical)



field theory:

Lagrangian field theory


quantum mechanical system, quantum probability

free field quantization

gauge theories

interacting field quantization



States and observables

Operator algebra

Local QFT

Perturbative QFT

Fields and quanta

fields and particles in particle physics

and in the standard model of particle physics:

force field gauge bosons

scalar bosons

matter field fermions (spinors, Dirac fields)

flavors of fundamental fermions in the
standard model of particle physics:
generation of fermions1st generation2nd generation3d generation
quarks (qq)
up-typeup quark (uu)charm quark (cc)top quark (tt)
down-typedown quark (dd)strange quark (ss)bottom quark (bb)
neutralelectron neutrinomuon neutrinotau neutrino
bound states:
mesonslight mesons:
pion (udu d)
ρ-meson (udu d)
ω-meson (udu d)
ϕ-meson (ss¯s \bar s),
kaon, K*-meson (usu s, dsd s)
eta-meson (uu+dd+ssu u + d d + s s)

charmed heavy mesons:
D-meson (uc u c, dcd c, scs c)
J/ψ-meson (cc¯c \bar c)
bottom heavy mesons:
B-meson (qbq b)
ϒ-meson (bb¯b \bar b)
proton (uud)(u u d)
neutron (udd)(u d d)

(also: antiparticles)

effective particles

hadrons (bound states of the above quarks)


in grand unified theory

minimally extended supersymmetric standard model




dark matter candidates


auxiliary fields



In nuclear physics (quantum chromodynamics) the bag model is an ad hoc effective model of quark confinement in hadrons, assuming literally that the quarks are constrained within an impenetrable membrane, the “bag”.

The Cheshire cat principle is the observation that this “bag” is not actually observable.

The Cheshire Cat Principle follows in holographic QCD, where the baryons are holographically realized as Skyrmions:

The Skyrmion is the ultimate topological bag model with zero size bag radius, lending further credence to the Cheshire cat principle. (Nielsen-Zahed 09)

effective field theories of nuclear physics, hence for confined-phase quantum chromodynamics:



Textbook account:

See also:

  • Atsushi Hosaka, Hiroshi Toki, Chiral bag model for the nucleon, Phys. Rept. 277 (1996) 65-188 (spire:429251, doi:10.1016/S0370-1573(96)00013-0)

  • Julius Kuti, Section 3 of: Quark confinement and the quark model, CERN - JINR School of Physics, Nafplion, Greece, 22 May - 4 Jun 1977, pp.79-128 (CERN-1977-018) (doi:10.5170/CERN-1977-018.79, pdf)

  • Luiz L. Lopes, Carline Biesdorf, Débora P. Menezes, Modified MIT Bag Models: Thermodynamic consistency, stability windows and symmetry group (arXiv:2005.13136)

  • Luiz L. Lopes, Carline Biesdorf, K. D. Marquez, Debora P. Menezes, Modified MIT Bag Models pt II: QCD phase diagram, hot quark stars and speed of sound (arXiv:2009.13552)

In relation to the Skyrme model

In relation to the Skyrmion model:

Combination of the omega-meson-stanilized Skyrme model with the bag model for nucleons:

  • Atsushi Hosaka, Omega stabilized chiral bag model with a surface ωqq\omega q q coupling, Nuclear Physics A Volume 546, Issue 3, 31 (1992) Pages 493-508 (doi:10.1016/0375-9474(92)90544-T)

Realized on D-branes

From the point of view of holographic QCD:

Last revised on August 17, 2021 at 15:24:12. See the history of this page for a list of all contributions to it.