K → πγ*γ* transitions at leading order and beyond
The result's identifiers
Result code in IS VaVaI
<a href="https://www.isvavai.cz/riv?ss=detail&h=RIV%2F00216208%3A11320%2F25%3A10510912" target="_blank" >RIV/00216208:11320/25:10510912 - isvavai.cz</a>
Result on the web
<a href="https://verso.is.cuni.cz/pub/verso.fpl?fname=obd_publikace_handle&handle=vnCWOY5ugH" target="_blank" >https://verso.is.cuni.cz/pub/verso.fpl?fname=obd_publikace_handle&handle=vnCWOY5ugH</a>
DOI - Digital Object Identifier
<a href="http://dx.doi.org/10.1103/6dzv-y8jy" target="_blank" >10.1103/6dzv-y8jy</a>
Alternative languages
Result language
angličtina
Original language name
K → πγ*γ* transitions at leading order and beyond
Original language description
The transition amplitude of a kaon to a pion and two off-shell photons is studied. First, it is computed at leading order (one-loop level) of the chiral perturbation theory expansion. Explicit analytical results for the leading-order amplitude are presented, constituting the first complete calculation for the doubly off-shell case. Subsequently, it is reevaluated by employing a refined diagrammatic notation and a generic ansatz incorporating effects beyond leading order. The dependence on the underlying KπPP vertex parameters is analyzed. This offers valuable insights into amplitude properties and allows inclusion of unitarity corrections from K RIGHTWARDS ARROW 3π, yielding the complete K RIGHTWARDS ARROW πγ*γ* amplitude structure. Both the charged and neutral channels are treated in parallel. The presented results provide crucial input for phenomenological studies of related rare decays like K RIGHTWARDS ARROW πℓ<sup>+</sup>ℓ<sup>-</sup>[γ] or K RIGHTWARDS ARROW πℓ<sup>+</sup><inf>1</inf>ℓ<sup>-</sup><inf>1</inf>ℓ<sup>+</sup><inf>2</inf>ℓ<sup>-</sup><inf>2</inf> and support ongoing precision measurements at experiments like NA62 at CERN. These results may also find application in other related processes, including η<sup>(')</sup> decays.
Czech name
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Czech description
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Classification
Type
J<sub>imp</sub> - Article in a specialist periodical, which is included in the Web of Science database
CEP classification
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OECD FORD branch
10300 - Physical sciences
Result continuities
Project
—
Continuities
I - Institucionalni podpora na dlouhodoby koncepcni rozvoj vyzkumne organizace
Others
Publication year
2025
Confidentiality
S - Úplné a pravdivé údaje o projektu nepodléhají ochraně podle zvláštních právních předpisů
Data specific for result type
Name of the periodical
Physical Review D
ISSN
2470-0010
e-ISSN
2470-0029
Volume of the periodical
112
Issue of the periodical within the volume
7
Country of publishing house
US - UNITED STATES
Number of pages
25
Pages from-to
073007
UT code for WoS article
001722995200001
EID of the result in the Scopus database
2-s2.0-105021363199