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We present the current status of our lattice calculation of the electromagnetic form factor of the pion with two flavours of non-perturbatively O(a)-improved Wilson fermions. Using twisted boundary conditions and stochastic sources we…

High Energy Physics - Lattice · Physics 2013-01-17 Bastian B. Brandt , Andreas Juttner , Hartmut Wittig

We calculate the valence quark distribution functions of the $\pi$ meson using the non-relativistic chiral constituent quark model. The $\pi$ wave function is obtained by solving the two-body Schr\"odinger equation within the framework of…

High Energy Physics - Phenomenology · Physics 2023-08-21 Qian Wu , Chengdong Han , Di Qing , Wei Kou , JuJun Xie , Fan Wang , Xurong Chen

We present an exploratory calculation of the $I=2$ $\pi-\pi$ scattering amplitude at threshold using Wilson fermions in the quenched approximation, including all the required contractions. We find good agreement with the predictions of…

High Energy Physics - Lattice · Physics 2009-10-22 Rajan Gupta , Apoorva Patel , Stephen Sharpe

Right now, we have not enough knowledge to determine the hadron distribution amplitudes (DAs) which are universal physical quantities in the high energy processes involving hadron for applying pQCD to exclusive processes. Even for the…

High Energy Physics - Phenomenology · Physics 2013-08-12 Tao Huang , Tao Zhong , Xing-Gang Wu

We calculate the electromagnetic form factor of the pion in quenched lattice QCD. The non-perturbatively improved Sheikoleslami-Wohlert lattice action is used together with the consistently O(a) improved current. We calculate the pion form…

High Energy Physics - Lattice · Physics 2009-11-10 J. van der Heide , J. H. Koch , E. Laermann

A short review is given of calculations of the pion electromagnetic and transition form factors within the framework of quantum chromodynamics. It is argued that both the perturbative and nonperturbative aspects of the Q^2 dependence of…

High Energy Physics - Phenomenology · Physics 2017-08-23 A. V. Radyushkin

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

We obtain the electromagnetic form factors of the $\gamma N\Delta$ transition by analyzing recent pion-electroproduction data using a fully relativistic dynamical model. Special care is taken to satisfy Ward-Takahashi identities for the…

Nuclear Theory · Physics 2010-01-18 G. L. Caia , V. Pascalutsa , J. A. Tjon , L. E. Wright

We calculate the electromagnetic pion form factor at intermediate space-like momentum transfer from the QCD sum rule for the correlation function of two {\it pseudoscalar } interpolating fields and the electromagnetic current. This…

High Energy Physics - Phenomenology · Physics 2009-10-28 Hilmar Forkel , Marina Nielsen

This is an English translation of my 1977 Russian preprint. It contains the first explicit definition of the pion distribution amplitude (DA), the expression for the pion form factor asymptotics in terms of the pion DA, and formulates the…

High Energy Physics - Phenomenology · Physics 2007-05-23 A. V. Radyushkin

The elastic and $\gamma \to \pi$ transition form factors of the pion along with its usual static observables are calculated within a light-front field approach to the constituent quark model. The focus of this exercise in a simple model is…

Nuclear Theory · Physics 2015-06-18 J. P. B. C. de Melo , B. El-Bennich , T. Frederico

We discuss the QCD sum-rule approach for the spacelike electromagnetic pion form factor in the $O(\alpha_s)$ approximation. We show that the nonlocality of the condensates is a key point to include nonperturbative contributions to the pion…

High Energy Physics - Phenomenology · Physics 2010-02-18 Alexander P. Bakulev , A. V. Pimikov , N. G. Stefanis

A scenario is investigated in which the leading-twist pion distribution amplitude phi_pi (x) is approximated by the pion decay constant f_pi for all essential values of the light-cone fraction x. A model for the light-front wave function…

High Energy Physics - Phenomenology · Physics 2014-11-20 A. V. Radyushkin

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

The $\gamma^\ast \gamma \to \pi^0$ transition form factor, $G(Q^2)$, is computed on the entire domain of spacelike momenta using a continuum approach to the two valence-body bound-state problem in relativistic quantum field theory: the…

We revisit the evaluations for the spacelike and timelike $\rho \pi$ transition form factors $F_{\rho\pi}(Q^2)$ and $G_{\rho\pi}(Q^2)$ with the inclusion of the the next-to-leading order (NLO) QCD contributions in the framework of the $k_T$…

High Energy Physics - Phenomenology · Physics 2018-06-26 Jun Hua , Shan Cheng , Ya-lan Zhang , Zhen-Jun Xiao

We perform an analysis of the form factors that rule the structure-dependent amplitude in the radiative pion decay. The resonance contributions to pion -> e nu_e gamma decays are computed through the proper construction of the vector and…

High Energy Physics - Phenomenology · Physics 2008-11-26 V. Mateu , J. Portoles

This review contains an overview over recent results for the electromagnetic iso-vector form factor of the pion obtained in lattice QCD with dynamical fermions. Particular attention is given to the extrapolation to the physical point and an…

High Energy Physics - Lattice · Physics 2014-02-14 Bastian B. Brandt

It is shown that the data on the pion charge form factor admit the possibility for a substantial sea-quark components in the pion wave function. If the charge form factor is calculated with instant form kinematics in a constituent quark…

High Energy Physics - Phenomenology · Physics 2008-11-26 Q. B. Li , D. O. Riska