A sample of 3984 candidates of the K+→π+γγ decay, with an estimated background of 291±14 events, was collected by the NA62 experiment at CERN during 2017–2018. In order to describe the observed di-photon mass spectrum, the next-to-leading order contribution in chiral perturbation theory was found to be necessary. The decay branching ratio in the full kinematic range is measured to be (9.61±0.17)×10−7. The first search for production and prompt decay of an axion-like particle with gluon coupling in the process K+→π+a, a→γγ is also reported.
Measurement of the K+ → π+γγ decay / Cortina Gil, E., Kleimenova, A., Minucci, E., Padolski, S., Petrov, P., Shaikhiev, A., Volpe, R., Numao, T., Petrov, Y., Velghe, B., Wong, V.W.S., Bryman, D., Fu, J., Hives, Z., Husek, T., Jerhot, J., Kampf, K., Zamkovsky, M., De Martino, B., Perrin-Terrin, M., et al.. - In: PHYSICS LETTERS. SECTION B. - ISSN 0370-2693. - 850:(2024), pp. 0-0. [10.1016/j.physletb.2024.138513]
Measurement of the K+ → π+γγ decay
Lo Chiatto P.Membro del Collaboration Group
;Bizzeti A.Membro del Collaboration Group
;
2024
Abstract
A sample of 3984 candidates of the K+→π+γγ decay, with an estimated background of 291±14 events, was collected by the NA62 experiment at CERN during 2017–2018. In order to describe the observed di-photon mass spectrum, the next-to-leading order contribution in chiral perturbation theory was found to be necessary. The decay branching ratio in the full kinematic range is measured to be (9.61±0.17)×10−7. The first search for production and prompt decay of an axion-like particle with gluon coupling in the process K+→π+a, a→γγ is also reported.
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