The classical nonlinear O(2) sigma model with a chemical potential

by Mr Debasish Banerjee (TIFR)

Thursday 26 Nov 2009, 14:30 → 15:30 Asia/Kolkata

AG-69 (Colaba Campus)

We study the classical non-linear O(2) sigma model with a coupling beta and chemical potential mu on a 2+1 dimensional Euclidean lattice. In the conventional formulation this model suffers from a sign problem at non-zero chemical potential and hence cannot be studied with the Wolff cluster algorithm. However, when formulated in terms of world-line of particles, the sign problem is absent. The world-line formulation can be studied very efficiently with the ``worm algorithm''. We use this algorithm to uncover the phase diagram in the (beta,mu) plane. In order to do this we develop finite size scaling relations and use them to extract the critical behaviour.