New constraints on the pion EM form factor using $ \Pi^{{ \prime}}_{}$ (- Q2 (original) (raw)

Electromagnetic form factor of the pion

2003

The Standard Model prediction for the magnetic moment of the muon requires a determination of the electromagnetic form factor of the pion at high precision. It is shown that the recent progress in ππ scattering allows us to obtain an accurate representation of this form factor on the basis of the data on e + e − → π + π − . The same method also applies to the form factor of the weak vector current, where the data on the decay τ → π − π 0 ντ are relevant. Unfortunately, however, the known sources of isospin breaking do not explain the difference between the two results. The discrepancy implies that the Standard Model prediction for the magnetic moment of the muon is currently subject to a large uncertainty. Talk given at the Workshop Continuous Advances in QCD 2002/Arkadyfest in honor of the 60th birthday of Arkady Vainshtein, Minneapolis, May 2002.

Rigorous pion electromagnetic form factor behavior in the spacelike region

Physical Review C, 2011

New precise experimental information on σ tot (e + e − → π + π −) is transferred into the spacelike region, by taking advantage of the analyticity. As a result a rigorous pion electromagnetic form factor behavior in the spacelike region is obtained. The latter with some existing model predictions is compared.

Vector form factor of the pion from unitarity and analyticity: A model-independent approach

Physical Review D, 2001

We study a model-independent parameterization of the vector pion form factor that arises from the constraints of analyticity and unitarity. Our description should be suitable up to √ s ≃ 1.2 GeV and allows a model-independent determination of the mass of the ρ(770) resonance, M ρ = (775.1 ± 0.5) MeV. We analyse the experimental data on τ − → π − π 0 ν τ , in this framework, and its consequences on the low-energy observables worked out by chiral perturbation theory. An evaluation of the two pion contribution to the anomalous magnetic moment of the muon, a µ , and to the fine structure constant, α(M 2 Z ), is also performed.

Vector form factor of the pion : A model-independent approach

Nuclear Physics B - Proceedings Supplements, 2003

We study a model-independent parameterization of the vector pion form factor that arises from the constraints of analyticity and unitarity. Our description should be suitable up to √ s ≃ 1.2 GeV and allows a modelindependent determination of the mass of the ρ(770) resonance. We analyse the experimental data on τ − → π − π 0 ντ and e + e − → π + π − in this framework, and its consequences on the low-energy observables worked out by chiral perturbation theory. An evaluation of the two pion contribution to the anomalous magnetic moment of the muon, aµ, and to the fine structure constant, α(M 2 Z ), is also performed.

Effective field theory description of the pion form factor

Physics Letters B, 1997

Using our present knowledge on effective hadronic theories, short-distance QCD information, the 1/N C expansion, analyticity and unitarity, we derive an expression for the pion form factor, in terms of m π , m K , M ρ and f π . This parameter-free prediction provides a surprisingly good description of the experimental data up to energies of the order of 1 GeV.

The Pion Electromagnetic Form Factor in a QCD-Inspired Model

Few-Body Systems, 2005

We present detailed numerical results for the pion space-like electromagnetic form factor obtained within a recently proposed model of the pion electromagnetic current in a confining light-front QCD-inspired model. The model incorporates the vector meson dominance mechanism at the quark level, where the dressed photon with q + > 0 decays in an interacting quarkantiquark pair, which absorbs the initial pion and produces the pion in the final state.

Pion electromagnetic form factor in Coulomb gauge QCD

Zeitschrift für Physik C Particles and Fields, 1989

The electromagnetic pion form factor and radius is calculated in a model which can be derived from Coulomb gauge QCD in an instantaneous approximation discussed recently. The results agree well with experimental data without further adjustment of parameters. They are also compared to results obtained in the Nambu-Jona-Lasinio and in the Vector Meson Dominance model.

A new parameterization for the pion vector form factor

Physics Letters B, 2012

A new approach to the parameterization of pion form factors is presented and for illustration applied to the pion vector form factor. It has the correct analytic structure, is at low energies consistent with recent high accuracy analyses of ππ scattering phase shifts and, at high energies, maps smoothly onto the well-known, successful isobar model.

Analysis of the pion formfactor in the time-like region

Physics Letters B, 1975

We perform a model independent analysis of the pion electromagnetic formfactor using the available space-like and time-like data. Our aim is to obtain information on the structure in the time-like region above the mo threshold. The phase below is assumed to be known from rm scattering. In the process of analytic continuation we use as stabilizing lever different types of bounds on the derivative of the formfactor.

Pion Electromagnetic Form Factor

Physical Review, 1968

A ratio of lattice correlation functions is identified from which the pion form factor can be obtained directly. Preliminary results from quenched Wilson simulations are presented.