We report recent results on charged kaon rare decays obtained by the NA48/2 collaboration. The Ke4 decays K± →p+p-e±n(Ke4(+-)) and K± →p0p0e±n(Ke4(00)) have been studied extensively, providing measurements of the branching ratios, together with the Ke4(+-) form factors and a precise determination of pp scattering lengths. Prospects for a study of Kμ4 decays are discussed. A new measurement of the branching ratio and gg invariant mass spectrum of K± → p±gg decays has been obtained from a combined analysis of NA48/2 and NA62 minimum-bias data. The analysis of a high statistics and low background sample of K± →p±p0g decays provided the first evidence of a non-zero interference between Inner Bremsstrahlung and Direct Emission amplitudes. The K± →p±p0e+e- decay has been observed for the first time, with a statistics of about 4500 events. The branching ratios of K± →p±e+e- and K± →p±μ+μ- decays have been measured with a few percent precision. Improved upper limits are given for CP-violating asymmetries in these decays, and for the branching fraction of the Lepton Number violating decay K± →πμ±μ±.
Kaon decays at NA48: Recent results and perspectives / Bizzeti, A.. - In: POS PROCEEDINGS OF SCIENCE. - ISSN 1824-8039. - 2012-:(2012), pp. N/A-N/A. (Intervento presentato al convegno 7th International Workshop on Chiral Dynamics: Theory and Experiment, CD 2012 tenutosi a Jefferson Lab, usa nel 2012).
Kaon decays at NA48: Recent results and perspectives
Bizzeti A.
2012
Abstract
We report recent results on charged kaon rare decays obtained by the NA48/2 collaboration. The Ke4 decays K± →p+p-e±n(Ke4(+-)) and K± →p0p0e±n(Ke4(00)) have been studied extensively, providing measurements of the branching ratios, together with the Ke4(+-) form factors and a precise determination of pp scattering lengths. Prospects for a study of Kμ4 decays are discussed. A new measurement of the branching ratio and gg invariant mass spectrum of K± → p±gg decays has been obtained from a combined analysis of NA48/2 and NA62 minimum-bias data. The analysis of a high statistics and low background sample of K± →p±p0g decays provided the first evidence of a non-zero interference between Inner Bremsstrahlung and Direct Emission amplitudes. The K± →p±p0e+e- decay has been observed for the first time, with a statistics of about 4500 events. The branching ratios of K± →p±e+e- and K± →p±μ+μ- decays have been measured with a few percent precision. Improved upper limits are given for CP-violating asymmetries in these decays, and for the branching fraction of the Lepton Number violating decay K± →πμ±μ±.
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