  Quantum critical points of many-body systems can be characterized by studying
response of the ground-state wave function to the change of the external
parameter, encoded in the ground-state fidelity susceptibility. This quantity
characterizes the quench dynamics induced by sudden change of the parameter. In
this framework, I analyze scaling relations concerning the probability of
excitation and the excitation energy, with the quench amplitude of this
parameter. These results are illustrated in the case of one-dimensional
sine-Gordon model.
