ELFT HÍRADÓ

[tcsaba <tcsaba AT eik.bme.hu>]

                   M E G H Í V Ó - I N V I T A T I O N

    Seminar Series of the Department of Theoretical Physics at the
           Budapest University of Technology and Economics


                           Balázs Pozsgay
                 (Department of Theoretical Physics,
           Budapest University of Technology and Economics)


              The (complete) Generalized Gibbs Ensemble
                    in the Heisenberg spin chains


We will consider non-equilibrium situations (and in particular quantum 
quenches) in the XXZ and XXX Heisenberg spin chains, which are one of 
the most important integrable models. It was suggested, that in such 
models the physical behaviour in the long-time limit can be described by 
the so-called Generalized Gibbs Ensemble (GGE). In contrast to the usual 
Gibbs ensemble the GGE also includes the higher conserved charges of the 
models. Whereas it was shown by our group in 2014 that the traditional 
approach to the GGE fails, later it was found that a broader GGE (which 
includes all the recently found ultra-local charges) can indeed give a 
correct description. In this talk we discuss certain aspects of this 
question. What does it mean to have infinite number of charges in an 
ensemble? In what sense is it complete? What is the range of its 
applicability? We also discuss the seemingly technical question of the 
validity of the so-called Y-system equations, which nevertheless has 
important consequences for the practical solution of the quench 
problems.


Időpont: 2016. november 11. péntek, 10:15
Helyszín: BME Fizikai Intézet, Elméleti Fizika Tanszék,
Budafoki út 8. F-épület, III lépcsőház, szemináriumi szoba