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dc.contributor.authorVasconcellos, Cesar Augusto Zenpt_BR
dc.contributor.authorCoelho, Hélio Teixeirapt_BR
dc.contributor.authorPilotto, Fernando Goncalvespt_BR
dc.contributor.authorBodmann, Bardo Ernst Josefpt_BR
dc.contributor.authorDillig, Manfredpt_BR
dc.contributor.authorRazeira, Moisespt_BR
dc.date.accessioned2018-08-22T02:32:07Zpt_BR
dc.date.issued1998pt_BR
dc.identifier.issn1434-6044pt_BR
dc.identifier.urihttp://hdl.handle.net/10183/181238pt_BR
dc.description.abstractIn the present work we propose a new bag model for hadrons, called the modi ed fuzzy bag model (MFBM). The distinguishing feature of this model is the suppression of the pion eld, as it enters the bag, by means of a scalar potential for the pions, while still preserving chiral symmetry. The mechanism of pion suppression in the MFBM is similar to the mechanism of quark suppression in the fuzzy bag model (FBM). The standard chiral transformation for the pion eld su ers a natural alteration in the MFBM, and as a result the model is chiral invariant. We present also a discussion of the FBM and study, in the quark sector, the implications of the soft surface of the bag on the expectation value of the mass operator. In the pion-quark sector, we study the e ects of the suppression of the pion eld on the form factor for the pion-nucleon interaction, on the pion-nucleon coupling constant g NN and on the nucleon axial charge gA. Calculations of the pion-nucleon form factor exhibit, in particular, an improvement over previous results. The pionic axial current induces, in the MFBM, a nonvanishing and orientation dependent contribution to axial charge. An analysis of the asymptotic behaviour of the axial charge shows that the role of the surface is to increase the di erence of the contributions associated to di erent orientations.en
dc.format.mimetypeapplication/pdfpt_BR
dc.language.isoengpt_BR
dc.relation.ispartofEuropean physical journal. C, Particles and fields. Berlin. Vol. 4, no. 1 (June 1998), p. 115-127pt_BR
dc.rightsOpen Accessen
dc.subjectModelo de sacolapt_BR
dc.subjectSimetrias quiralpt_BR
dc.subjectConstantes de acoplamento de partículas elementarespt_BR
dc.subjectFatores de formapt_BR
dc.subjectNucleonspt_BR
dc.subjectInterações pion-núcleonpt_BR
dc.subjectQuarkspt_BR
dc.titleA chiral bag model with a soft surface : structure and solutions of the fuzzy and the modified fuzzy bag modelpt_BR
dc.typeArtigo de periódicopt_BR
dc.identifier.nrb000325077pt_BR
dc.type.originEstrangeiropt_BR


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