Dominique Mouhanna

Optimization of the derivative expansion in the nonperturbative renormalization group

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

Frustrated heisenberg magnets: A nonperturbative approach

partial^2

CORRELATED FERMIONS IN A ONE-DIMENSIONAL QUASIPERIODIC POTENTIAL

of the derivative expansion. This approach allows us to select optimized cut-off functions and to improve the accuracy of the critical exponents

XY frustrated systems: Continuous exponents in discontinuous phase transitions

nu

Monte Carlo calculation of the spin-stiffness of the two-dimensional Heisenberg model

and

Phase diagram and criticality of the random anisotropy model in the large-N limit

eta

INTERACTIONS IN QUASICRYSTALS

. 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.

Low-temperature properties of two-dimensional frustrated quantum antiferromagnets.

Frustrated magnets are a notorious example where the usual perturbative methods are in conflict. Using a nonperturbative Wilson-like approach, we get a coherent picture of the physics of Heisenberg frustrated magnets everywhere between

Spontaneous symmetry breaking in quantum frustrated antiferromagnets.

d=2

Symmetry breaking and finite size scaling in antiferromagnets

and