Hoferichter M, Hoid BL, Kubis B, Lüdtke J. Improved Standard-Model Prediction for π^{0}→e^{+}e^{-}.
PHYSICAL REVIEW LETTERS 2022;
128:172004. [PMID:
35570465 DOI:
10.1103/physrevlett.128.172004]
[Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/13/2021] [Revised: 08/18/2021] [Accepted: 03/25/2022] [Indexed: 06/15/2023]
Abstract
We present an improved standard-model (SM) prediction for the dilepton decay of the neutral pion. The loop amplitude is determined by the pion transition form factor for π^{0}→γ^{*}γ^{*}, for which we employ a dispersive representation that incorporates both spacelike and timelike data as well as short-distance constraints. The resulting SM branching fraction, Br[π^{0}→e^{+}e^{-}]=6.25(3)×10^{-8}, sharpens constraints on physics beyond the SM, including pseudoscalar and axial-vector mediators.
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