# Chiral pion dynamics for spherical bags

## Abstract

We develop a phenomenological model for non-strange hadrons, based on the assumption that the strongly interacting particles are made up of quarks. The quarks are confined ad hoc, in a manner first introduced by the MIT group. Inside the confinement region (bag) the quarks interact via gluon-exchange. We introduce a pion field outside the bag, coupled to the quarks at the surface in such a way as to preserve chiral symmetry. We prove using the Goldberger-Treiman relation, that our pion field asymptotically coincides with the Yukawa field of a static distributed source. The pions contribute an attractive self-energy term to the mass of the hadron, which tends to reduce the size of the bag. The pion contribution breaks the SU(4) symmetry and thus distinguishes, e.g., between the nucleon and the isobar masses. Further, we develop a formalism for pion emission and absorption processes, whose main ingredient is the pion source term which appears as a consequence of the pion-quark coupling. We find good agreement with experiments for the ..delta.. decay into p..pi.. and for the rho decay into two ..pi..'s, if the bag has a radius of the order of 0.3 to 0.4 fm. We build a model for themore »

- Authors:

- Publication Date:

- Research Org.:
- New York Univ., NY (USA)

- OSTI Identifier:
- 5164747

- Resource Type:
- Thesis/Dissertation

- Resource Relation:
- Other Information: Thesis (Ph. D.)

- Country of Publication:
- United States

- Language:
- English

- Subject:
- 72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS; BAG MODEL; CHIRAL SYMMETRY; HADRONS; NUCLEONS; ELECTROMAGNETIC FORM FACTORS; CONFINEMENT; FORM FACTORS; GLUONS; MASS; PARTICLE DECAY; PIONS; QUARKS; SYMMETRY BREAKING; VECTOR DOMINANCE MODEL; BARYONS; BOSONS; COMPOSITE MODELS; DECAY; ELEMENTARY PARTICLES; EXTENDED PARTICLE MODEL; FERMIONS; MATHEMATICAL MODELS; MESONS; PARTICLE MODELS; PARTICLE PROPERTIES; POSTULATED PARTICLES; PSEUDOSCALAR MESONS; QUARK MODEL; SYMMETRY; 645204* - High Energy Physics- Particle Interactions & Properties-Theoretical- Strong Interactions & Properties

### Citation Formats

```
Vento-Torres, V.
```*Chiral pion dynamics for spherical bags*. United States: N. p., 1980.
Web.

```
Vento-Torres, V.
```*Chiral pion dynamics for spherical bags*. United States.

```
Vento-Torres, V. Tue .
"Chiral pion dynamics for spherical bags". United States.
```

```
@article{osti_5164747,
```

title = {Chiral pion dynamics for spherical bags},

author = {Vento-Torres, V},

abstractNote = {We develop a phenomenological model for non-strange hadrons, based on the assumption that the strongly interacting particles are made up of quarks. The quarks are confined ad hoc, in a manner first introduced by the MIT group. Inside the confinement region (bag) the quarks interact via gluon-exchange. We introduce a pion field outside the bag, coupled to the quarks at the surface in such a way as to preserve chiral symmetry. We prove using the Goldberger-Treiman relation, that our pion field asymptotically coincides with the Yukawa field of a static distributed source. The pions contribute an attractive self-energy term to the mass of the hadron, which tends to reduce the size of the bag. The pion contribution breaks the SU(4) symmetry and thus distinguishes, e.g., between the nucleon and the isobar masses. Further, we develop a formalism for pion emission and absorption processes, whose main ingredient is the pion source term which appears as a consequence of the pion-quark coupling. We find good agreement with experiments for the ..delta.. decay into p..pi.. and for the rho decay into two ..pi..'s, if the bag has a radius of the order of 0.3 to 0.4 fm. We build a model for the electromagnetic form factors of the nucleon, in which the interaction with the meson cloud is described by vector meson dominance models. Again we find good agreement with experimental data for small cores of the order of 0.3 to 0.4 fm. In the last part of our work, we construct two chiral invariant models, a linear one with pion and sigma degrees of freedom, and a non-linear one with only pion degrees of freedom. Using the experimental ..pi..N coupling constant as an input we obtain masses for the baryons of the order of 1 GeV and pion decay constants of the order of 0.1 GeV for a variety of values of the radius.},

doi = {},

url = {https://www.osti.gov/biblio/5164747},
journal = {},

number = ,

volume = ,

place = {United States},

year = {1980},

month = {1}

}