2016/11/30 by C. Hanhart, S. Holz, B. Kubis +3
Physics and Astronomy · #Branching (polymer chemistry) #Branching fraction #Form factor (electronics) #Particle physics theoretical and experimental studies #Pion #Quantum Chromodynamics and Particle Interactions #Quantum and Classical Electrodynamics #R-value (soils) #Radiative transfer #hep-ex #hep-ph #nucl-ex #nucl-th
paper · pdf · doi:10.1140/epjc/s10052-017-4651-x
published as Eur. Phys. J. C77 (2017) 98 · 11+2 pages, 7+1 figures; v3: erratum appended that rectifies erroneous treatment of the BaBar data
openalex created_date 2016/12/08 · openalex publication_date 2017/02/01 · arxiv created 2018/06/19 · arxiv updated 2018/06/20 · openalex updated_date 2026/08/06
We analyze the most recent data for the pion vector form factor in the timelike region, employing a model-independent approach based on dispersion theory. We confirm earlier observations about the inconsistency of different modern high-precision data sets. Excluding the BaBar data, we find an updated value for the isospin-violating branching ratio \mathscr B(ω → π +π -) = (1.46± 0.08) × 10-2 . As a side result, we also extract an improved value for the pion vector or charge radius, √(⟨ rV2⟩ ) = 0.6603(5)(4) \text fm , where the first uncertainty is statistical as derived from the fit, while the second estimates the possible size of nonuniversal radiative corrections. In addition, we demonstrate that modern high-quality data for the decay η '→ π +π -γ will allow for an even improved determination of the transition strength ω → π +π - .