1999/01/11 by Fabrizio Gabbiani, Gabbiani, Fabrizio
Physics and Astronomy · #Dark Matter and Cosmic Phenomena #FOS: Physical sciences #High Energy Physics - Phenomenology (hep-ph) #Particle physics theoretical and experimental studies #Quantum Chromodynamics and Particle Interactions #hep-ph
paper · pdf · doi:10.48550/arxiv.hep-ph/9901262
Ph.D. Thesis, September 1997. 104 pages, 31 eps figures. LaTeX, uses epsf.sty, umthesis.sty (included). Two references added, misprints corrected
openalex publication_date 1999/01/11 · arxiv created 1999/03/05 · arxiv updated 2009/11/30 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/01
Rare kaon decays are an important testing ground of the electroweak flavor theory: They can provide new signals of CP-violating phenomena. The interplay of long-distance QCD effects in strangeness-changing transitions can be analyzed with Chiral Perturbation Theory techniques. In particular, two rare kaon decays are analyzed: The first decay, KL -> pi0 e+e-, is being searched for as a signal of direct Delta S = 1 CP violation. We provide a thorough updating of the analysis of the three components of the decay: 1) Direct CP violation, 2) CP violation through the mass matrix and 3) CP-conserving (two-photon) contributions. First the chiral calculation of the KS -> pi0 e+e- rate is updated to include recent results on the nonleptonic amplitude. Then we systematically explore the uncertainties in this method. The CP-conserving amplitude remains somewhat uncertain, but present indications are such that there may be a sizable CP-violating asymmetry in the e+, e- energies from the interference of CP-conserving and CP-violating amplitudes. This may potentially be useful in determining whether direct CP violation is present. The second decay, KL -> pi0 gamma e+e-, which occurs at a higher rate than the nonradiative process KL -> pi0 e+e-, can be a background to CP violation studies using the latter reaction. The leading order chiral loop contribution to KL -> pi0 gamma e+e- is completely calculable.