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Paper   IPM / P / 11248
School of Physics
  Title:   Tachyonic Resonance Preheating in Expanding Universe
1.  A.A. Abolhasani
2.  H. Firouzjahi
3.  M.M. Sheikh-Jabbari
  Status:   Published
  Journal: Phys. Rev. D
  Vol.:  81
  Year:  2010
  Pages:   043524
  Supported by:  IPM
We study the tachyonic resonance preheating generated from the bosonic trilinear ϕχ2 interactions following inflation period caused by the quartic inflationary potential λϕ4/4. In particular, we focus on the effects of expansion of the Universe during the preheating era. The trilinear interaction, in contrast to the four-leg ϕ2χ2, breaks the conformal symmetry explicitly and the resonant source term becomes non-periodic, making the Floquet theorem inapplicable. We find that the occupation number of the produced χ-particles has a non-linear exponential growth with exponent  ∼ x3/2, where x is the conformal time. This should be contrasted with preheating from a periodic resonant source, arising for example from four-legs ϕ2χ2 interaction, where the occupation number has a linear exponential growth. We present an analytic method to compute the interference term coming from phases accumulated in non-tachyonic scattering regions and show that the effects of the interference term causes ripples on x3/2 curve, a result which is confirmed by numerical analysis. Studying the effects of back-reaction of the χ-particles, we show that tachyonic resonance preheating in our model can last long enough to transfer most of the energy from the background inflation field ϕ, providing an efficient model for preheating in the chaotic inflation models.

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