Precise measurement of the decay KL → π0γγ

A. Lai*, D. Marras, A. Bevan, R. S. Dosanjh, T. J. Gershon, B. Hay, G. E. Kalmus, C. Lazzeroni, D. J. Munday, M. D. Needham, E. Olaiya, M. A. Parker, T. O. White, S. A. Wotton, G. Barr, G. Bocquet, A. Ceccucci, T. Cuhadar-Dönszelmann, D. Cundy, G. D'AgostiniN. Doble, V. Falaleev, L. Gatignon, A. Gonidec, B. Gorini, G. Govi, P. Grafström, W. Kubischta, A. Lacourt, M. Lenti, S. Luitz, I. Mikulec, A. Norton, S. Palestini, B. Panzer-Steindel, G. Tatishvili, H. Taureg, M. Velasco, H. Wahl, C. Cheshkov, P. Hristov, V. Kekelidze, D. Madigojine, N. Molokanova, Yu Potrebenikov, A. Zinchenko, I. Knowles, V. Martin, R. Sacco, A. Walker, M. Contalbrigo, P. Dalpiaz, J. Duclos, P. L. Frabetti, A. Gianoli, M. Martini

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

68 Scopus citations


The decay rate of KL → π0 γγ has been measured with the NA48 detector at the CERN SPS. A total of 2558 KL π0γγ candidates have been observed with a residual background of 3.2%. The branching ratio is determined to be (1.36 ± 0.03(stat) ± 0.03(syst) ± 0.03(norm)) × 10-6 and the vector coupling constant av = -0.46 ± 0.03(stat) ± 0.04(syst). This result suggests that the CP-violation effects are dominating in the KL → π0e+e- decay. An upper limit for the KL → π0γγ decay rate in the two photon mass region mγγ < mπ0 is also given.

Original languageEnglish (US)
Pages (from-to)229-240
Number of pages12
JournalPhysics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics
Issue number3-4
StatePublished - Jun 6 2002

ASJC Scopus subject areas

  • Nuclear and High Energy Physics


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