JOINT ICTP/SISSA STATISTICAL PHYSICS SEMINAR:"Form factors in finite volume and finite temperature correlators"

[Statistical Physics Group]

JOINT ICTP/SISSA STATISTICAL PHYSICS SEMINAR





Tuesday, 20 January 2009   -    12:30 hrs





Lecture Room D

SISSA Main Building





Gabor TAKACS

( Eötvös University, Budapest )





" Form factors in finite volume and

finite temperature correlators "



Abstract



I review recent work related to the volume dependence of matrix  
elements of local fields (form factors), giving a description valid  
to all orders in inverse powers of the volume (i.e. only neglecting  
contributions that decay exponentially with volume). This method can  
be used to test exact solutions (derived using bootstrap methods in  
integrable models) against numerical data obtained by solving the  
field theory in a truncated state space; it is also useful in  
extracting matrix elements from numerical data such as those obtained  
from e.g. lattice field theory. Matrix elements with disconnected  
pieces require special attention. Such matrix elements are important  
in computing finite temperature correlation functions. I give a new  
method for generating a low temperature expansion, which is evaluated  
for the one-point function up to third order, confirming a series  
expansion conjectured by Leclair and Mussardo. Time permitting, I  
also briefly show how the results can be extended to a situation with  
boundaries.