Martedi' 17 febbraio 2015, ore 15:00 - Seminario Teorico INFN - Dr Giuseppe Burgio - Topological order and the vacuum of Yang-Mills theories -
Relatore: Dr Giuseppe Burgio - Universita' di Tubinga
Luogo:Sala Feynman
E-mail organizzatore: francesco.direnzo@fis.unipr.it
Abstract
We introduce a non-local topological order parameter for SU(2) Yang-
Mills theories discretized on a lattice, the center flux z. We show
that:
• Center vortex topological sectors, classified by π_1(SO(3))=Z2,
can only exist in the ordered phase of z;
• Depending on the dimension 2 ≤ d ≤ 4 and action chosen, z
exhibits a critical behaviour sharing striking features with
the Kosterlitz-Thouless type of transitions, although belonging
to a novel universality class;
• Such critical behaviour does not depend on the temperature T.
Yang-Mills theories can thus exist in two different continuum
phases, characterized by a topologically ordered or disordered
vacuum; this reminds of a quantum phase transition, albeit
controlled by the choice of symmetries and not by a physical
parameter.