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Setting Limits on Supersymmetry Using Simplified Models
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Particle-antiparticle asymmetries from annihilations.

Iason Baldes1, Nicole F Bell1, Kalliopi Petraki2

  • 1ARC Centre of Excellence for Particle Physics at the Terascale, School of Physics, The University of Melbourne, Victoria 3010, Australia.

Physical Review Letters
|November 15, 2014
PubMed
Summary

This study explores how particle-antiparticle asymmetries can originate from 2→2 annihilations, challenging the traditional focus on heavy particle decays. It demonstrates a novel mechanism for generating these asymmetries within a toy model framework.

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Area of Science:

  • Particle Physics
  • Cosmology
  • Quantum Field Theory

Background:

  • Particle-antiparticle asymmetries are crucial for understanding the universe's composition.
  • Current models predominantly explain these asymmetries through heavy particle decays (1→2) and inverse processes.
  • An alternative mechanism originating from 2→2 annihilations has not been fully explored.

Purpose of the Study:

  • To investigate the generation of particle-antiparticle asymmetries through 2→2 annihilation processes.
  • To establish the theoretical framework and conditions for asymmetry generation via annihilations.
  • To demonstrate the feasibility of this mechanism in a simplified model.

Main Methods:

  • Reviewing general conditions on reaction rates derived from S-matrix unitarity and CPT invariance.
  • Developing a toy model to implement these conditions for 2→2 annihilations.
  • Formulating Boltzmann equations to describe the evolution of asymmetries within the model.
  • Solving the Boltzmann equations to provide an example solution.

Main Results:

  • Demonstrated that 2→2 annihilations can generate particle-antiparticle asymmetries.
  • Identified specific conditions on reaction rates required for asymmetry generation.
  • Successfully implemented and solved a toy model illustrating the mechanism.

Conclusions:

  • The study provides a novel mechanism for generating particle-antiparticle asymmetries beyond traditional decay processes.
  • The findings suggest that 2→2 annihilations are a viable source of cosmic asymmetry.
  • This work opens new avenues for exploring the origins of matter-antimatter imbalance in the universe.