QCD studies at NA48

Not scheduled
15m
WG4 QCD and Hadronic Final States

Speaker

Cristina Lazzeroni (University of Birmingham (GB))

Description

We report the first observation of the very rare decay K+- -> pi+- pi0 e+ e- by the NA48/2 experiment. From a clean sample of almost 2000 reconstructed signal events, we have determined the branching fraction with high precision and measured the e+ e- invariant mass distribution, which allows to differentiate between different decay models. Besides, the NA48/2 experiment has recently published a detailed study of the Ke4 decay mode K —> pi0 pi0 e nu based on 65000 candidates with a low 1% background contamination. The achieved experimental precision brings evidence for isospin breaking mass effects and final state pi pi scattering. Theoretical calculations will have to face a new precision challenge when using such improved inputs to extract for example low energy constants of Chiral Perturbation Theory.

Primary author

Cristina Lazzeroni (University of Birmingham (GB))

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