Dynamics in the Ising field theory after a quantum quench

Understand

We study the real-time dynamics of the order parameter $<\sigma(t)>$ in the Ising field theory after a quench in the fermion mass, which corresponds to a quench in the transverse field of the corresponding transverse field Ising chain.

• We focus on quenches within the ordered phase.
• The long-time behaviour is obtained analytically by a resummation of the leading divergent terms in a form-factor expansion for $<\sigma(t)>$.
• Our main result is the development of a method for treating divergences associated with working directly in the field theory limit.