Effective freefermionic form factors and the XY spin chain
Abstract
We introduce effective form factors for onedimensional lattice fermions with arbitrary phase shifts. We study tau functions defined as series of these form factors. On the one hand we perform the exact summation and present tau functions as Fredholm determinants in the thermodynamic limit. On the other hand simple expressions of form factors allow us to present the corresponding series as integrals of elementary functions. Using this approach we rederive the asymptotics of static correlation functions of the XY quantum chain at finite temperature.
 Publication:

SciPost Physics
 Pub Date:
 March 2021
 DOI:
 10.21468/SciPostPhys.10.3.070
 arXiv:
 arXiv:2012.02079
 Bibcode:
 2021ScPP...10...70G
 Keywords:

 Condensed Matter  Statistical Mechanics;
 Mathematical Physics
 EPrint:
 SciPost Phys. 10, 070 (2021)