Freiburg 2008 – scientific programme
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T: Fachverband Teilchenphysik
T 38: Bottom und Charm Produktion und Zerfall II
T 38.6: Talk
Tuesday, March 4, 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.