Final results from the KTeV experiment on the decayKL→π0γγ

Abstract

We report on a new measurement of the branching ratio B(KL → π 0 γγ) using the KTeV detector. We reconstruct 1982 events with an estimated background of 608, that results in B(KL → π 0 γγ) = (1.29 ± 0.03stat ± 0.05syst) × 10 −6. We also measure the parameter, aV , which characterizes the strength of vector meson exchange terms in this decay. We find aV = −0.31 ± 0.05stat ± 0.07syst. These results utilize the full KTeV data set collected from 1997 to 2000 and supersede earlier KTeV measurements of the branching ratio and aV .

New Physics Implications of Recent Search for KL→π0νν¯Kitahara1, Okui2, Pérez3 et al. 2020Phys. Rev. Lett.7911260View full textAdd to dashboardCite

“…The B(KL → π 0 X) = 10 −4 , 10 −6 and 10 −8 are indicated on the plot. The green shaded region is constrained from KTEV search for KL → π 0 γγ assuming B(X → γγ) = 1 [20]. of the fact that K L → π 0 νν search is the neutrino flavor blind, these upper bounds would be the same order as the predictions of Eq.…”

Constraints on scalar leptoquarks from lepton and kaon physics

“…Their differential branching fractions are given by Eq. (66 We notice in the last row of Table 9 that a very stringent constraint arises from the current experimental upper limit on these modes [115]. The lepton-flavour-violating decays are absent in the SM and have not yet been seen in experiments.…”

Constraints on long-lived light scalars with flavor-changing couplings and the KOTO anomaly

“…• The are also some searches of the rare decays K + → π + χχ with χχ = e + e − , µ + µ − , γγ, which have been performed by NA48/2 [41,42] and NA62 [43]. The neutral lepton decays K L → π 0 χχ (with χχ = e + e − , µ + µ − , γγ) are also searched for in the KTeV experiment [44][45][46]. In these searches, the electrons, muons and photons are all from the primary kaon decay vertex, thus they are not applicable for the long-lived S discussed here for the KOTO anomaly.…”