title: Relations between short-range and long-range Ising models.
abstract: We perform a numerical study of the long-range (LR) ferromagnetic Ising model with power law decaying interactions (J∝r{-d-σ}) on both a one-dimensional chain (d=1) and a square lattice (d=2). We use advanced cluster algorithms to avoid the critical slowing down. We first check the validity of the relation connecting the critical behavior of the LR model with parameters (d,σ) to that of a short-range (SR) model in an equivalent dimension D. We then study the critical behavior of the d=2 LR model close to the lower critical σ, uncovering that the spatial correlation function decays with two different power laws: The effect of the subdominant power law is much stronger than finite-size effects and actually makes the estimate of critical exponents very subtle. By including this subdominant power law, the numerical data are consistent with the standard renormalization group (RG) prediction by Sak [Phys. Rev. B 8, 281 (1973)], thus making not necessary (and unlikely, according to Occam's razor) the recent proposal by Picco [arXiv:1207.1018] of having a new set of RG fixed points in addition to the mean-field one and the SR one.
authors.affiliation: Institut de Physique Théorique, CEA/DSM/IPhT-CNRS/URA 2306 CEA-Saclay, F-91191 Gif-sur-Yvette, France.
authors.forename: Maria Chiara
authors.initials: MC
authors.lastname: Angelini
authors.affiliation: Dipartimento di Fisica, INFN-Sezione di Roma 1, CNR-IPCF UOS Roma, Università "La Sapienza," Piazzale Aldo Moro 5, I-00185 Roma, Italy.
authors.forename: Giorgio
authors.initials: G
authors.lastname: Parisi
authors.affiliation: Dipartimento di Fisica, INFN-Sezione di Roma 1, CNR-IPCF UOS Roma, Università "La Sapienza," Piazzale Aldo Moro 5, I-00185 Roma, Italy.
authors.forename: Federico
authors.initials: F
authors.lastname: Ricci-Tersenghi
mesh_terms: D000465:Algorithms; D003198:Computer Simulation; D060328:Magnetic Phenomena; D008962:Models, Theoretical; D009010:Monte Carlo Method; D013696:Temperature