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We use the available information on the ratio between the electric and magnetic proton form factors coming from recently published space-like data and from the few available time-like data. We apply a dispersive procedure on these data to…

High Energy Physics - Phenomenology · Physics 2009-01-07 R. Baldini , C. Bini , P. Gauzzi , M. Mirazita , M. Negrini , S. Pacetti

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

A global fit to the data from different collaborations (CELLO, CLEO, BaBar) on the pion-photon transition form factor is carried out using light-cone sum rules. The analysis includes the next-to-leading QCD radiative corrections and the…

High Energy Physics - Phenomenology · Physics 2012-01-17 A. P. Bakulev , S. V. Mikhailov , A. V. Pimikov , N. G. Stefanis

We present a combined analysis of the space- and time-like electromagnetic pion form factors in light-cone perturbative QCD with transverse momentum dependence and Sudakov suppression. Including the non-perturbative ``soft' QCD and power…

High Energy Physics - Phenomenology · Physics 2014-11-20 Jiunn-Wei Chen , Hiroaki Kohyama , Kazuaki Ohnishi , Udit Raha , Yue-Long Shen

We obtain the distribution amplitude (DA) of the pion from its light-front wave functions in the basis light-front quantization framework. This light-front wave function of the pion is given by the lowest eigenvector of a light-front…

High Energy Physics - Phenomenology · Physics 2021-11-24 Chandan Mondal , Sreeraj Nair , Shaoyang Jia , Xingbo Zhao , James P. Vary

We study the electromagnetic form factor of the pion and kaons at low-energies with the use of Chiral Perturbation Theory. The analysis is performed within the three flavour framework and at next-to-next-to-leading order. We explain…

High Energy Physics - Phenomenology · Physics 2011-03-22 Johan Bijnens , Pere Talavera

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

Recent developments in the QCD description of the pion structure are reviewed. The CLEO pion-photon transition data analysis favors a distribution amplitude for the pion that is double-humped but endpoint-suppressed. After a short outline…

High Energy Physics - Phenomenology · Physics 2009-11-10 A. P. Bakulev , S. V. Mikhailov , N. G. Stefanis

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 present an investigation of the electromagnetic pion form factor, $F_\pi(Q^2)$, at small values of the four-momentum transfer $Q^2$ ($\lesssim 0.25$ GeV$^2$), based on the gauge configurations generated by European Twisted Mass…

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

The pion electromagnetic form factor F_{\pi}(Q^{2}) is calculated at the leading order of pQCD using the running coupling constant (\alpha_{S}(Q^{2}(1-x)(1-y))) approach. The resummed expression for F_{\pi}(Q^{2}) is found. It is shown that…

High Energy Physics - Phenomenology · Physics 2008-02-03 Shahin S. Agaev

We study consistently the pion's static observables and the elastic and \gamma*\gamma -> \pi^0 transition form factors within a light-front model. Consistency requires that all calculations are performed within a given model with the same…

Nuclear Theory · Physics 2013-01-30 B. El-Bennich , J. P. B. C. de Melo , T. Frederico

The large $N_c$ limit provides relations that can be used to calculate the $\gamma^\ast N \to \Delta(1232)$ quadrupole form factors at low and intermediate $Q^2$ under the assumption of the pion cloud dominance. There are two limitations in…

High Energy Physics - Phenomenology · Physics 2016-12-13 G. Ramalho

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

We study the pion electromagnetic and $\gamma^* + \pi^0 \to \gamma$ transition form factors at intermediate momentum transfer. We calculate soft, nonperturbative corrections to the leading perturbative amplitudes which arise from the $q\bar…

High Energy Physics - Phenomenology · Physics 2010-03-04 A. Szczepaniak , A. G. Williams

The pion and kaon electromagnetic form factors $F_{M}(Q^2)$ are calculated at the leading order of pQCD using the running coupling constant method. In computations dependence of the meson distribution amplitudes on the hard scale $Q^2$ is…

High Energy Physics - Phenomenology · Physics 2009-10-31 S. S. Agaev

The extrapolation of nucleon magnetic form factors calculated within lattice QCD is investigated within a framework based upon heavy baryon chiral effective-field theory. All one-loop graphs are considered at arbitrary momentum transfer and…

High Energy Physics - Phenomenology · Physics 2008-11-26 P. Wang , D. B. Leinweber , A. W. Thomas , R. D. Young

We investigate the pion and kaon (pi^+, K^+, K^0) electromagnetic form factors in the space-like region: Q^2 ~< 1 GeV, based on the gauged low-energy effective chiral action from the instanton vacuum in the large N_c limit. Explicit flavor…

High Energy Physics - Phenomenology · Physics 2008-11-26 Seung-il Nam , Hyun-Chul Kim

The simultaneous investigation of the pion electromagnetic form factor in the space- and time-like regions within a light-front model allows one to address the issue of non-valence components of the pion and photon wave functions. Our…

High Energy Physics - Phenomenology · Physics 2009-11-11 J. P. B. C. de Melo , T. Frederico , E. Pace , G. Salme