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Reheating the Universe after Inflation Via Resonant Interactions

Yarahmadi, Amir | 2022

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 55405 (04)
  4. University: Sharif University of Technology
  5. Department: Physics
  6. Advisor(s): Abolhasani, Ali Akbar
  7. Abstract:
  8. The inflation paradigm solves the so-called flatness problem of the standard cosmo- logical model and explains the homogeneity of the Universe by adding a period of exponential expansion at early times to the standard scenario. Moreover, it provides a mechanism for generating density perturbations, serving as the seed of large-scale structures. One of the successes of inflation is predicting primordial scale-invariant perturbations that agree with the observations of cosmic background radiation. Nev- ertheless, there will be a cold, matter-free universe after exponential expansion, so one needs a process that leads to a hot cosmos containing standard particles after the end of inflation, the so-called (p)reheating period. The two main proposals for getting stan- dard cosmology after inflation are preheating and warm inflation theories. In post- inflation reheating theory, considering the coupling between the inflation field and a scalar field– as a representative of the standard model field– an explosive production of particles in the thermal equilibrium can happen. This thesis investigates the effects of producing particles of an extra field during and after inflation via a modulated mass coupling. Specifically, we study a model in which the mass of the extra degrees of free- dom - the particle representative of the standard particle model - is modulated by the amplitude of the inflation field. We will answer at what rate these particles are pro- duced at the end of inflation. We also address whether we can have efficient reheating under this model
  9. Keywords:
  10. Warm Inflation ; Reheating ; Cosmology ; Inflationary Model ; Standard Cosmology

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