Departamento de Gravitación y Teoría de Campos

                          Seminarios 2012

  

                          Instituto de Ciencias Nucleares, UNAM
[ ICN-UNAM]

Jueves 6 de septiembre, a las 17:00 hrs en la sala de seminarios del ICN

Wolfgang Bietenholz (ICN, UNAM)

Solving the Sign Problem in a sigma Model

We apply a cluster algorithm to study the 2d O(3) model at large vacuum angles theta. We introduce half-integer topological charges for the clusters, which provides a definition of merons. The enables the use of an improved estimator which overcomes the sign problem in this case. We find a second order phase transition at theta -> pi, in agreement with a conjectured link to quantum spin chains. It is driven by the neutralisation of merons and anti-merons.