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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 pi-pi scattering allows us to obtain an…

High Energy Physics - Phenomenology · Physics 2017-08-23 H. Leutwyler

We develop a formalism to calculate form factor and charge density distribution of pion in the chiral limit using the holographic dual model of QCD with hard-wall cutoff. We introduce two conjugate pion wave functions and present analytic…

High Energy Physics - Phenomenology · Physics 2008-11-26 H. R. Grigoryan , A. V. Radyushkin

In a study of the elastic pion form factor for large momentum transfers based on a modified perturbative QCD (PQCD) approach we have included helicity components that are customarily neglected. Along with the inclusion of transverse…

High Energy Physics - Phenomenology · Physics 2009-10-28 Siwen Wang , Leonard S. Kisslinger

We improve, in the energy region between $\bar{K}K$ threshold and $\sim~1.4$ GeV, the energy-dependent phase shift analysis of $\pi\pi$ scattering presented in a previous paper. For the S0 wave we have included more data above $\bar{K}K$…

High Energy Physics - Phenomenology · Physics 2014-11-18 R. Kaminski , J. R. Pelaez , F. J. Yndurain

The electromagnetic form factor of the pion is calculated in a pseudoscalar field theoretical model which constituent quarks. We extract the form factor using the "+" component of the electromagnetic current in the light-cone formalism. For…

High Energy Physics - Phenomenology · Physics 2009-10-30 J. P. B. C. de Melo , H. W. L. Naus , T. Frederico

In this work, we employ a dispersion relation that allows to recover the electromagnetic form factor of the pion from its modulus along the unitarity cut. Unlike the standard dispersive approach, this method extends in a straightforward…

High Energy Physics - Phenomenology · Physics 2024-10-24 Pablo Sanchez-Puertas , Enrique Ruiz Arriola

We analyze a pion form factor formulation which fulfills the Analyticity requirement within the Hidden Local Symmetry (HLS) Model. We show that it implies an $s$--dependent dressing of the $\rho-\gamma$ VMD coupling and an account of…

Nuclear Theory · Physics 2008-11-26 M. Benayoun , P. David , L. DelBuono , Ph. Leruste , H. B. O'Connell

We study the shape parameters of the $D\pi$ scalar and vector form factors using as input dispersion relations and unitarity for the moments of suitable heavy-light correlators evaluated with Operator Product Expansions, including…

High Energy Physics - Phenomenology · Physics 2012-07-25 B. Ananthanarayan , I. Caprini , I. Sentitemsu Imsong

Recently, the BABAR collaboration published (arXiv:0905.4778) data for the photon-pion transition form factor $F_{\pi\gamma\gamma^{\ast}}(Q^{2})$, which are in strong contradiction to the predictions of the standard factorization approach…

High Energy Physics - Phenomenology · Physics 2010-04-20 A. E. Dorokhov

I present results for the pion's electromagnetic form factor in the spacelike region, which implement the most advanced perturbative information currently available for this observable in conjunction with a pion distribution amplitude that…

High Energy Physics - Phenomenology · Physics 2007-05-23 N. G. Stefanis

The pion electromagnetic form factor is investigated by using the dispersion relation with the superconvergence condition, which was proposed to synthesize the vector meson dominance model and QCD. The absorptive part is given as an…

High Energy Physics - Phenomenology · Physics 2007-05-23 Keiji Watanabe , Hirohisa Ishikawa , Masami Nakagawa

The pion decay constants of the lowest orbitally excited states of the nucleon and the $\Delta(1232)$ along with the corresponding axial transition form factors are calculated with Poincar\'e covariant constituent-quark models with instant,…

Nuclear Theory · Physics 2009-11-10 B. Julia-Diaz , D. O. Riska , F. Coester

The quadratic pion scalar radius, \la r^2\ra^\pi_s, plays an important role for present precise determinations of \pi\pi scattering. Recently, Yndur\'ain, using an Omn\`es representation of the null isospin(I) non-strange pion scalar form…

High Energy Physics - Phenomenology · Physics 2008-11-26 Jose A. Oller , Luis Roca

Recent measurement of the $\gamma\gamma^\ast$ form factor of the neutral pion in the high $Q^2$ region disagrees with {\em a priori} predictions of QCD-based calculations. We comment on existing explanations, and analyze a possibility that…

High Energy Physics - Phenomenology · Physics 2012-03-15 David McKeen , Maxim Pospelov , J. Michael Roney

We provide an in-depth analysis of the $\pi$ distribution amplitude in terms of two different Gegenbauer representations. Detailed predictions for the $\pi-\gamma$ transition form factor are presented, obtained with light-cone sum rules.…

High Energy Physics - Phenomenology · Physics 2014-12-01 N. G. Stefanis , S. V. Mikhailov , A. V. Pimikov

The scalar form factors for the pions and kaons are calculated in SU(3) Chiral Perturbation Theory at order $p^6$, in the isospin limit $m_u=m_d=\hat{m}$. We find in general sizable corrections of $\mathcal{O}(p^6)$. We use our results to…

High Energy Physics - Phenomenology · Physics 2009-11-10 Johan Bijnens , Pierre Dhonte

We provide a theoretical update of the calculations of the pi0-gamma*-gamma form factor in the LCSR framework, including up to six polynomials in the conformal expansion of the pion distribution amplitude and taking into account twist-six…

High Energy Physics - Phenomenology · Physics 2011-03-22 S. S. Agaev , V. M. Braun , N. Offen , F. A. Porkert

Pion scattering amplitudes were recently found to vanish on specific kinematic loci, and to factorise close to these loci into a product of two lower-point amplitudes of an extended theory. We propose a diagrammatic representation of pion…

High Energy Physics - Theory · Physics 2025-10-31 Yang Li , Tianzhi Wang , Tomáš Brauner , Diederik Roest

We review the status of baryon form factors with a special focus on the nucleon electromagnetic form factors which are known best. First, we give an introduction into the dispersive analyses and emphasize the role of unitarity and…

High Energy Physics - Phenomenology · Physics 2024-12-23 Yong-Hui Lin , Hans-Werner Hammer , Ulf-G. Meißner

We analyze the pion transition form factor using dispersion theory. We calculate the singly-virtual form factor in the time-like region based on data for the $e^+e^-\to 3\pi$ cross section, generalizing previous studies on…

High Energy Physics - Phenomenology · Physics 2014-12-19 Martin Hoferichter , Bastian Kubis , Stefan Leupold , Franz Niecknig , Sebastian P. Schneider