Models of Isospin Breaking in the Pion Form Factor: Consequences for the Determination of Pi_{ρω}(m_rho^2) and (g-2)_mu/2

Abstract

We study the implications of several recent high-precision measurements of the pion form factor in the region of the rho-omega interference "shoulder" for (i) the extraction of the rho-omega mixing matrix element, Pi_{ρω}(m_rho^2), and (ii) the evaluation of the isospin-breaking (IB) correction needed to incorporate hadronic tau decay data into the determination of the Standard Model expectation for the leading order hadronic contribution, [a_mu]_{had}^{LO}, to the anomalous magnetic moment of the muon, focussing, in the latter case, on the model-dependence of the rho-omega mixing component of the IB correction. We consider a range of different models for the broad rho contribution to the e^+e^- --> ππamplitude, applying these models to each experimental data set, and find that the model dependence of the rho-omega mixing correction is significantly larger than the uncertainty induced by experimental errors for any individual model. We also find that, for each such model, the recent data allows one to separate rho-omega mixing and direct omega --> ππcoupling contributions to the amplitude, and hence to obtain a reasonably precise extraction of Pi_{ρω}(m_rho^2), uncontaminated by direct omega --> ππcoupling effects, for use in meson exchange model calculations of charge symmetry breaking in NN scattering.

25 pages, 4 figures. Final published version. Main change is inclusion of a detailed discussion of the source of differences between the present work and M. Davier et al. (arXiv:0906.5443v3)

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Cited by in corpus (15)

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• An Update of the HLS Estimate of the Muon g-2
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• Consequences of the BaBar e^+e^- --> pi^+pi^- Measurement for the Determination of Model-Dependent rho-omega Mixing Effects in Pi_{ρω}(m_ρ^2) and (g-2)_mu
• Dilepton Radiation from Strongly Interacting Systems
• A ChPT estimate of the strong-isospin-breaking contribution to the anomalous magnetic moment of the muon
• Direct $CP$ violation of three bodies decay process from the resonance effect
• Effect of resonance for $CP$ asymmetry of the decay process ${\bar{B}}_s\to P{\pi }^{+}{\pi }^{-}$ in perturbative QCD
• $CP$ violation induced by the double resonance for pure annihilation decay process in Perturbative QCD
• Multiple solutions in extracting physics information from experimental data
• Direct $CP$ violation for ${\bar{B}}_s^0\to \varphi {\pi }^{+}{\pi }^{-}$ in Perturbative QCD
• Baryonic content of the pion
• Sizing the double pole resonant enhancement in $e^{+}{e}^{-}\to {\pi }^0{\pi }^0\gamma$ cross section and ${\tau }^{-}\to {\pi }^{-}{\pi }^0{\nu }_{\tau }\gamma$ decay
• Recent progress on isospin breaking corrections and their impact on the muon g-2 value
• Evaluation of the three-flavor quark-disconnected contribution to the muon anomalous magnetic moment from experimental data