Measurement of the Dalitz-decay branching ratio of the π0

Abstract

Abstract. The ratio B = Γ (π 0 → e + e − γ)/Γ (π 0 → γγ) is measured by comparing the production rates of the π 0 in the two decay channels. The analysis is based on approximately four million hadronic decays of the Z boson recorded by the ALEPH detector in the years 1991 to 1995. The value of B is determined to be (1.140 ± 0.041)%. A recalculation of the Particle Data Group world average gives rise to a slightly improved error, and moves the world average closer to the theoretical value.

Precise Determination of the Branching Ratio of the Neutral-Pion Dalitz Decay

“…Numerically, ∆R aπ =0 L&S = 0.10378 × 10 −3 and ∆R a univ π L&S = 0.10414(7) × 10 −3 . The two approaches are compatible and should be compared with our result (13). However, the 1γIR contribution was, due to inappropriate assumptions and arguments based on Low's theorem [47][48][49], considered negligible and left out; see also Refs.…”

A data-driven approach to ${{\rm{\pi }}}^{0},{\rm{\eta }}$ and ${{\rm{\eta }}}^{\prime}$ single and double Dalitz decays

“…From the experimental side, the current status is the following. The PDG reported value for the branching ratio of the decay π 0 → e + e − γ is (1.174 ± 0.035)% [1], which is obtained from the PDG fits of the ratio Γ(π 0 → e + e − γ)/Γ(π 0 → γγ) = (1.188 ± 0.035)% (the latest measurement of this ratio, (1.140±0.041)%, was performed by ALEPH in 2008 [2]) and B(π 0 → γγ) = (98.823±0.034)%. It is worth commenting that this is the second most important decay mode of the π 0 .…”

Noncommutativity and Lorentz Violation in Relativistic Heavy Ion Collisions at LHC

“…Concerning the π 0 contribution, its differential cross section can be evaluated by taking into account the branching ratio B(π 0 → γe + e + /π 0 → γγ) 0.012 [20] and that for p γ T ≥ 50GeV the π 0 → γγ differential cross section, for Pb-Pb collision at √ s = 5.5…”