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J. R. Shepard

Publications and source records attributed to J. R. Shepard.

20 records · Page 2Linked to original sources

Exact 1-Fermion Loop Contributions in 1+1 Dimensional Solitons

We find solutions to the 1+1 dimensional scalar-only linear sigma model. A new method is used to compute 1-fermion loop contributions exactly and agreement with published results employing other methods is excellent. A renormalization scheme which differs from that commonly used in such calculations but similar to that required in 1+3 dimensions is also presented. We compare ``kink'' {\it versus} ``shallow bag'' solutions paying careful attention to the implications of the 1-fermion loop contributions for the stability of the former. We find that, for small fermion multiplicities, self-consistent shallow bag solutions are always more bound than their metastable kink counterparts. However, as the fermion multiplicity increases, shallow bags evolve into kinks which eventually are the only self-consistent configurations. This situation is qualitatively the same for the two renormalization schemes considered. When we construct ``baryons'', each containing three fermions, the kink configuration is typically more bound than the shallow bag when 1-fermion loop contributions are included.

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Transverse response functions in the $Δ$-resonance region

We calculate transverse response functions for quasi-elastic electron scattering at high momentum transfers in a relativistic Hartree approximation in configuration space. We treat the excitation of the $Δ$ resonance using its free mass and width. Good agreement with experiment is found in the dip region.

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