J. Vidal

Publications (3)0 Total impact

• Source

  Available from: arxiv.org

  Article: Nonperturbative renormalization group approach to the Ising model: a derivative expansion at order $\partial^4$

  L. Canet, B. Delamotte, D. Mouhanna, J. Vidal
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  ABSTRACT: On the example of the three-dimensional Ising model, we show that nonperturbative renormalization group equations allow one to obtain very accurate critical exponents. Implementing the order $\partial^4$ of the derivative expansion leads to $\nu=0.632$ and to an anomalous dimension $\eta=0.033$ which is significantly improved compared with lower orders calculations. Comment: 4 pages, 3 figures
  02/2003;
• Source

  Available from: arxiv.org

  Article: Optimization of the derivative expansion in the nonperturbative renormalization group

  L. Canet, B. Delamotte, D. Mouhanna, J. Vidal
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  ABSTRACT: We study the optimization of nonperturbative renormalization group equations truncated both in fields and derivatives. On the example of the Ising model in three dimensions, we show that the Principle of Minimal Sensitivity can be unambiguously implemented at order $\partial^2$ of the derivative expansion. This approach allows us to select optimized cut-off functions and to improve the accuracy of the critical exponents $\nu$ and $\eta$. The convergence of the field expansion is also analyzed. We show in particular that its optimization does not coincide with optimization of the accuracy of the critical exponents. Comment: 13 pages, 9 PS figures, published version
  11/2002;
• Source

  Available from: arxiv.org

  Article: Randomly dilute Ising model: A nonperturbative approach

  M. Tissier, D. Mouhanna, J. Vidal, B. Delamotte
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  ABSTRACT: The N-vector cubic model relevant, among others, to the physics of the randomly dilute Ising model is analyzed in arbitrary dimension by means of an exact renormalization-group equation. This study provides a unified picture of its critical physics between two and four dimensions. We give the critical exponents for the three-dimensional randomly dilute Ising model which are in good agreement with experimental and numerical data. The relevance of the cubic anisotropy in the O(N) model is also treated.
  10/2001;