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This talk presents issues pertaining to the quark structure of the pion within QCD, both from the theoretical and from the experimental point of view. We review and discuss the pion-photon transition form factor and the pion's…

High Energy Physics - Phenomenology · Physics 2008-11-07 N. G. Stefanis

We present our results on the electromagnetic form factor of pion over a wide range of $Q^2$ using lattice QCD simulations with Wilson-clover valence quarks and HISQ sea quarks. We study the form factor at the physical point with a lattice…

High Energy Physics - Lattice · Physics 2022-01-07 Xiang Gao , Nikhil Karthik , Swagato Mukherjee , Peter Petreczky , Sergey Syritsyn , Yong Zhao

We calculate pion vector and scalar form factors in two-flavor lattice QCD and study the chiral behavior of the vector and scalar radii <r^2>_{V,S}. For a direct comparison with chiral perturbation theory (ChPT), chiral symmetry is exactly…

High Energy Physics - Phenomenology · Physics 2014-11-20 Takashi Kaneko

We propose a dispersive representation of the charged pion vector form factor that is consistent with chiral symmetry and fulfills the constraints imposed by analyticity and unitarity. Unknown parameters are fitted to the very precise data…

High Energy Physics - Phenomenology · Physics 2013-09-10 D. Gómez Dumm , P. Roig

We try to understand the recently observed anomalous behavior of the photon-to-pion transition form factor in the holographic QCD approach. First the holographic description of the anomalous \gamma^*\gamma^*\pi^0 form factor is reviewed and…

High Energy Physics - Phenomenology · Physics 2012-02-01 Fen Zuo , Tao Huang

We revisit the hard QCD contributions to the pion gravitational form factors (GFFs), in terms of the twist-2,3 pion distribution amplitudes (DA), including novel semi-hard contributions from the instantons. The pion DAs are evaluated in the…

High Energy Physics - Phenomenology · Physics 2024-10-16 Wei-Yang Liu , Edward Shuryak , Ismail Zahed

The charged pion form factor, Fpi(Q^2), is an important quantity which can be used to advance our knowledge of hadronic structure. However, the extraction of Fpi from data requires a model of the 1H(e,e'pi+)n reaction, and thus is…

We calculate pion vector and scalar form factors in two-flavor lattice QCD and study the chiral behavior of the vector and scalar radii <r^2>_{V,S}. Numerical simulations are carried out on a 16^3 x 32 lattice at a lattice spacing of 0.12…

High Energy Physics - Lattice · Physics 2012-08-27 JLQCD , TWQCD collaborations , : , S. Aoki , T. W. Chiu , H. Fukaya , S. Hashimoto , T. H. Hsieh , T. Kaneko , H. Matsufuru , J. Noaki , T. Onogi , E. Shintani , N. Yamada

We discuss the pion form factor calculation in QCD.We shortly consider the main points of the nonlocal condensate QCD sum rule approach and show its results for the pion form factor, $F_\pi(Q^2)$. These results are compared with predictions…

High Energy Physics - Phenomenology · Physics 2015-05-20 Alexander P. Bakulev

We present the first calculation of the pion electromagnetic form factor at physical light quark masses. This form factor parameterises the deviations from the behaviour of a point-like particle when a photon hits the pion. These deviations…

High Energy Physics - Lattice · Physics 2017-10-23 Jonna Koponen , Francis Bursa , Christine T. H. Davies , Rachel J. Dowdall , G. Peter Lepage

We compute the electromagnetic form factor of a "pion" with mass m_pi=330MeV at low values of Q^2\equiv -q^2, where q is the momentum transfer. The computations are performed in a lattice simulation using an ensemble of the RBC/UKQCD…

High Energy Physics - Lattice · Physics 2009-01-06 P. A. Boyle , J. M. Flynn , A. Juttner , C. Kelly , H. Pedroso de Lima , C. M. Maynard , C. T. Sachrajda , J. M. Zanotti

The $\gamma^{*}\rho^0\to\pi^0$ transition form factor is extracted from recent result for the $\gamma^* \gamma^* \pi^0$ form factor obtained in the extended hard-wall AdS/QCD model with a Chern-Simons term. In the large momentum region, the…

High Energy Physics - Phenomenology · Physics 2014-11-20 Fen Zuo , Yu Jia , Tao Huang

The holographic graviton soft-wall model, introduced to describe the spectrum of scalar and tensor glueballs, is improved to incorporate the realization of chiral-symmetry as in QCD. Such a goal is achieved by including the longitudinal…

High Energy Physics - Phenomenology · Physics 2022-08-10 M. Rinaldi , F. A. Ceccopieri , V. Vento

The lightest meson, the pion, features two faces -- one is the elementary Goldstone boson of QCD and the other is the structured bound state of quarks and gluons. To accommodate both in a single light-front wave function in the valence…

High Energy Physics - Theory · Physics 2022-12-05 Yang Li , Pieter Maris , James P. Vary

We present an analysis of QCD sum rules for pion form factor in next-to-leading order of perturbation theory for the case of pseudoscalar pion currents. The essential instanton contribution is reanalysed with account for present more…

High Energy Physics - Phenomenology · Physics 2009-11-10 V. V. Braguta , A. I. Onishchenko

We present an analysis of QCD sum rules for pion form factor in next-to-leading order of perturbation theory for the case of axial-vector pion currents. The theoretical predictions for Q^2-dependence of pion form factor are in good…

High Energy Physics - Phenomenology · Physics 2009-11-10 V. V. Braguta , A. I. Onishchenko

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 present a precise calculation of the pion form factor using overlap fermions on seven ensembles of 2+1-flavor domain-wall configurations with pion masses varying from 139 to 340 MeV. Taking advantage of the fast Fourier transform and…

High Energy Physics - Phenomenology · Physics 2021-10-13 Gen Wang , Jian Liang , Terrence Draper , Keh-Fei Liu , Yi-Bo Yang

We report on the fully analytic calculation of the leading-power contribution to the photon-pion transition form factor $\gamma \, \gamma^{\ast} \to \pi^0$ at two loops in QCD. The applied techniques are based on hard-collinear…

High Energy Physics - Phenomenology · Physics 2021-10-29 Jing Gao , Tobias Huber , Yao Ji , Yu-Ming Wang

We present a formula that allows one to calculate the pion form factor in the timelike region 2mpi <= sqrt{s} <= 4mpi in lattice QCD. The form factor quantifies the contribution of two-pion states to the vacuum polarization. It must be…

High Energy Physics - Lattice · Physics 2012-04-04 Harvey B. Meyer