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  • Ultrasoft Contribution to the Positronium Hyperfine Splitting
  • Marcu, Simona Rahela
  • English
  • positronium
    hyperfine splitting
  • Oct 3, 2011 4:09 AM
  • Thesis
  • English
  • Adobe PDF
  • 685292 bytes
  • Positronium consists of an electron and positron in a bound state, a purely leptonic system and therefore an excellent test of QED (quantum electrodynamics). The ground state is characterized by two different spin configurations: spin-singlet and spin-triplet states. The difference between the corresponding energy levels is called the hyperfine splitting. Currently the discrepancy between theory and experiment is 3.9 standard deviations for this quantity. We are computing the ultrasoft contribution to the positronium hyperfine splitting. It represents the time-delayed exchange of a photon with energy of the order of the binding energy between the electron and positron. The full theoretical expression of the ultrasoft contribution was found using perturbation theory, and expansion of the positronium wavefunction at the origin about the Coulomb approximation. The expression was then evaluated using Mathematica and asymptotic approximations have been made when an exact numerical value could not be computed. The final result increases the discrepancy to 4.3 standard deviations. New experimental results are needed in order to solve the discrepancy.
  • Master's
  • Master of Science
  • Department of Physics
  • Fall 2011
  • Penin, Alexander (Physics)
  • Prus-Czarnecki, Andrzej (Physics)
    Kravchinsky, Vadim (Physics)
    Troitsky, Vladimir (Mathematics)