nLab quark bag model

Idea

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)

Related concepts

• QCD

• confinement

• Cheshire cat principle

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

• with effective ligh meson fields:

  • chiral perturbation theory

    • vector meson dominance

    • hidden local symmetry

  • with emergent (solitonic) baryon fields:

    • quark bag model

    • Skyrme model

    • Witten-Sakai-Sugimoto model

  • with explicit effective baryon fields:

    • baryon chiral perturbation theory

    • quantum hadrodynamics

      • Walecka model

  • with explicit quark fields:

    • quark-meson coupling model

References

General

Textbook account:

• Ulrich Mosel, Bag Models of Hadrons (doi:10.1007/978-3-662-03841-3_16), Chapter 16 in: Fields, Symmetries, and Quarks, Springer 1999 (doi:10.1007/978-3-662-03841-3)

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)

• Amirhossein Rezaei, Mohammad Parsa Akrami, Exact and Efficient Numerical approaches to MIT Bag Model [arXiv:2403.15833]

Via worldline formalism:

• Lucas Manzo, Worldline approach for spinor fields in manifolds with boundaries [arXiv:2403.00218]

In relation to the Skyrme model

In relation to the Skyrmion model:

• G. E. Brown, Mannque Rho, The Chiral Bag, Comments Nucl. Part. Phys. 18 (1988) no.1, 1-29 (spire:18025)

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

• Atsushi Hosaka, Omega stabilized chiral bag model with a surface $\omega q q$ 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:

• Holger Bech Nielsen, Ismail Zahed, The Cheshire Cat Principle from Holography (doi:10.1142/9789814280709_0017, arXiv:0904.0429), Chapter 17 in: The Multifaceted Skyrmion, World Scientific 2016 (doi:10.1142/9710)