 
Summary: Study of the preheating phase of chaotic inflation
Paul R. Anderson,1,* Carmen MolinaPari´s,2,+
David Evanich,1
and Gregory B. Cook1,
1
Department of Physics, Wake Forest University, WinstonSalem, North Carolina 27109, USA
2
Department of Applied Mathematics, School of Mathematics, University of Leeds, Leeds LS2 9JT, United Kingdom
(Received 8 January 2008; published 10 October 2008)
Particle production and its effects on the inflaton field are investigated during the preheating phase of
chaotic inflation using a model consisting of a massive scalar inflaton field coupled to N massless quantum
scalar fields. The effects of spacetime curvature and interactions between the quantum fields are ignored.
A large N expansion is used to obtain a coupled set of equations including a backreaction equation for the
classical inflaton field. Previous studies of preheating using these equations have been done. Here the first
numerical solutions to the full set of equations are obtained for various values of the coupling constant and
the initial amplitude of the inflaton field. States are chosen so that initially the backreaction effects on the
inflaton field are small and the mode equations for the quantum fields take the form of Mathieu equations.
Potential problems relating to the parametric amplification of certain modes of the quantum fields are
identified and resolved. A detailed study of the damping of the inflaton field is undertaken. Some
predictions of previous studies are verified and some new results are obtained.
