Scaling and infrared divergences in the replica field theory of the Ising spin glass |
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Authors: | T Temesvári C De Dominicis I Kondor |
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Institution: | 1. Institute for Theoretical Physics, E?tv?s University, Pázmány Péter sétány 1, Bld. A, 1117, Budapest, Hungary 2. Service de Physique Théorique, CEA Saclay, 91191, Gif-sur-Yvette Cedex, France 3. Department of Physics of Complex Systems, E?tv?s University, Pázmány Péter sétány 1, Bld. A, 1117, Budapest, Hungary
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Abstract: | Replica field theory for the Ising spin glass in zero magnetic field is studied around the upper critical dimension d=6. A scaling theory of the spin glass phase, based on Parisi's ultrametrically organised order parameter, is proposed. We
argue that this infinite step replica symmetry broken (RSB) phase is nonperturbative in the sense that amplitudes of scaling
forms cannot be expanded in term of the coupling constant w2. Infrared divergent integrals inevitably appear when we try to compute amplitudes perturbatively, nevertheless the -expansion of critical exponents seems to be well-behaved. The origin of these problems can be traced back to the unusual
behaviour of the free propagator having two mass scales, the smaller one being proportional to the perturbation parameter
w2 and providing a natural infrared cutoff. Keeping the free propagator unexpanded makes it possible to avoid producing infrared
divergent integrals. The role of Ward-identities and the problem of the lower critical dimension are also discussed.
Received 23 December 1998 and Received in final form 23 March 1999 |
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Keywords: | PACS 75 10 Nr Spin-glass and other random models - 05 50 +q Lattice theory and statistics (Ising Potts etc ) |
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