Nilanjana Datta, Tom Kennedy
Expansions for one quasiparticle states in spin 1/2 systems
(59K, LaTex)

ABSTRACT.  Convergent expansions of the wavefunctions for the ground state 
and low-lying excited states of quantum transverse Ising systems 
are obtained. These expansions are employed to prove that 
the dispersion relation for a single quasi-particle 
has a convergent expansion.