Measurement of the K+ → π+γγ decay
(2024) Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics — Vol. 850 (2024)
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- Abstract
- A sample of 3984 candidates of the <math altimg="si1.svg"><msup><mrow><mi>K</mi></mrow><mrow><mo linebreak="badbreak" linebreakstyle="after">+</mo></mrow></msup><mo stretchy="false">→</mo><msup><mrow><mi>π</mi></mrow><mrow><mo linebreak="badbreak" linebreakstyle="after">+</mo></mrow></msup><mi>γ</mi><mi>γ</mi></math> decay, with an estimated background of <math altimg="si2.svg"><mn>291</mn><mo>±</mo><mn>14</mn></math> 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 <math altimg="si3.svg"><mo stretchy="false">(</mo><mn>9.61</mn><mo>±</mo><mn>0.17</mn><mo stretchy="false">)</mo><mo>×</mo><msup><mrow><mn>10</mn></mrow><mrow><mo linebreak="badbreak" linebreakstyle="after">−</mo><mn>7</mn></mrow></msup></math>. The first search for production and prompt decay of an axion-like particle with gluon coupling in the process <math altimg="si4.svg"><msup><mrow><mi>K</mi></mrow><mrow><mo linebreak="badbreak" linebreakstyle="after">+</mo></mrow></msup><mo stretchy="false">→</mo><msup><mrow><mi>π</mi></mrow><mrow><mo linebreak="badbreak" linebreakstyle="after">+</mo></mrow></msup><mi>a</mi></math>, <math altimg="si5.svg"><mi>a</mi><mo stretchy="false">→</mo><mi>γ</mi><mi>γ</mi></math> is also reported.
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Cortina Gil, E., Minucci, E., Padolski, S., Rumenov Petrov, P., Volpe, R., Kleimenova, A., Shaikhiev, A., Lurkin, N., NA62, & et al. (2024). Measurement of the K+ → π+γγ decay. Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics, 850. https://doi.org/10.1016/j.physletb.2024.138513 (Original work published 2024)