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A quark-model framework for studying nuclear medium effects on nucleonresonances is described and applied here to pion photoproduction on thedeuteron, which is the simplest composite nucleon system and serves as a firsttest case. Pion photoproduction on nuclei is discussed within a chiralconstituent quark model in which the quark degrees of freedom are explicitlyintroduced through an effective chiral Lagrangian for thequark-pseudoscalar-meson coupling. The advantage of this model is that acomplete set of nucleon resonances can be systematically included with alimited number of parameters. Also, the systematic description of the nucleonand its resonances at quark level allows us to self-consistently relate thenuclear medium's influence on the baryon properties to the intrinsic dynamicaspects of the baryons. As the simplest composite nucleus, the deuteronrepresents the first application of this effective theory for mesonphotoproduction on light nuclei. The influence of the medium on the transitionoperators for a free nucleon is investigated in the Delta resonance region. Noevidence is found for a change of the Delta properties in the pionphotoproduction reaction on the deuteron since the nuclear medium here involvesjust one other nucleon and the low binding energy implies low nuclear density.However, we show that the reaction mechanism is in principle sensitive tochanges of Delta properties that would be produced by the denser nuclear mediumof heavier nuclei through the modification of the quark model parameters.Comment: Revtex, 8 pages, 4 figure

A quark model framework for the study of nuclear medium effects