Freiburg 2008 – wissenschaftliches Programm

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T: Fachverband Teilchenphysik

T 38: Bottom und Charm Produktion und Zerfall II

T 38.6: Vortrag

Dienstag, 4. März 2008, 18:00–18:15, Peterhof-HS 2

Results from the K^± → π^± γ γ and K^± → π^± e⁺ e⁻ γ Decays with the NA48/2 Detector — •Cristina Morales — NA48 Kollaboration, Insitut für Physik,Universität Mainz

The decay K^± → π^± γ γ provides a stringent test of chiral perturbation theory (ChPT) since the leading contributions start at O(p⁴). It includes one undetermined coupling constant, ĉ, for which various models predict different values of O(1). Both the branching fraction and the spectrum shape of K^± → π^± γ γ are sensitive to ĉ. In addition, recent studies show that O(p⁴) pole contributions should not be neglected in K^±→ π^±γ γ decays. Depending on its value, the pole contribution can be completely negligible, or as large as 30% of the total branching ratio. The decay K^± → π^± γ γ is being analyzed using the data set of NA48/2 of 2003. The decay K^± → π^± e⁺ e⁻ γ is similar to the decay K^± → π^± γ γ, with an internal conversion of one of the photons. NA48/2 has reported the first observation of this decay and the model independent measurement of its branching ratio. These results have been derived from a data sample of 120 events.