The new published measurements of the K± → π± γγ decay with minimum bias data samples collected by the two experiments NA48/2 and NA62 are discussed. The results include a model independent decay rate measurement and fits to Chiral Perturbation Theory (ChPT) description. The model independent branching ratio in the kinematic range z = (mγγ/mK)2 > 0.2, obtained by combining the NA48/2 and NA62 results, is BMI = (0.965 ± 0.63) × 10-6. The combined branching ratio in the full kinematic range assuming a ChPT description is BChPT = (1.003±0.056)×10-6. The uncertainties are dominated by the statistical errors. The data support the ChPT prediction for a cusp in the di-photon invariant mass spectrum at the two pion threshold and are in agreement with both O(p4) and O(p6) ChPT predictions. © 2015 Elsevier B.V.

ChPT test at NA48 and NA62 experiment at CERN

GIUDICI, SERGIO;LAMANNA, GIANLUCA;SOZZI, MARCO STANISLAO;
2015-01-01

Abstract

The new published measurements of the K± → π± γγ decay with minimum bias data samples collected by the two experiments NA48/2 and NA62 are discussed. The results include a model independent decay rate measurement and fits to Chiral Perturbation Theory (ChPT) description. The model independent branching ratio in the kinematic range z = (mγγ/mK)2 > 0.2, obtained by combining the NA48/2 and NA62 results, is BMI = (0.965 ± 0.63) × 10-6. The combined branching ratio in the full kinematic range assuming a ChPT description is BChPT = (1.003±0.056)×10-6. The uncertainties are dominated by the statistical errors. The data support the ChPT prediction for a cusp in the di-photon invariant mass spectrum at the two pion threshold and are in agreement with both O(p4) and O(p6) ChPT predictions. © 2015 Elsevier B.V.
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11568/861088
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