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We describe the present status of the pion distribution amplitude (DA) as it originated from several sources: (i) a nonperturbative approach, based on QCD sum rules with nonlocal condensates, (ii) an O(\alpha_s) QCD analysis of the CLEO…

High Energy Physics - Phenomenology · Physics 2007-05-23 A. P. Bakulev

We present a calculation of pion electromagnetic and scalar form factors in two-flavor QCD with the non-perturbatively O(a)-improved Wilson fermion. Chiral extrapolation of the corresponding charge radius is discussed based on the chiral…

We analyse various $U(1)_{EM}$ form factors of mesons at strong coupling in an $\mathcal{N}=2$ flavored version of $\mathcal{N}=4$ $SYM$ which becomes conformal in the UV. The quark mass breaks the conformal symmetry in the IR and generates…

High Energy Physics - Theory · Physics 2008-11-26 D. Rodriguez-Gomez , J. Ward

Within the framework provided by quantum chromodynamics's Schwinger-Dyson equations (SDEs), the pion's electromagnetic form factor is computed using solutions of the Bethe-Salpeter equation (BSE) that have finite spacial momentum, and…

High Energy Physics - Phenomenology · Physics 2024-02-27 Shaoyang Jia , Ian Cloët

In this paper we present the result of a direct QCD sum rule calculation of the transition form factor \gamma\gamma* -> pi^o in the region of moderately large invariant momentum Q^2 > 1GeV^2 of the virtual photon. In contrast to pQCD, we…

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

We compute the Kl3 and pion form factors using partially twisted boundary conditions. The twists are chosen so that the Kl3 form factors are calculated directly at zero momentum transfer (q^2=0), removing the need for a q^2 interpolation,…

High Energy Physics - Lattice · Physics 2010-01-21 P. A. Boyle , J. M. Flynn , A. Jüttner , C. Kelly , H. Pedroso de Lima , C. M. Maynard , C. T. Sachrajda , J. M. Zanotti

We review the pion-photon transition form factor calculated in the Schwinger-Dyson approach and an impulse approximation. We present results for it far above the scales presently accessible for measurement, up to 36 GeV^2, and demonstrate…

High Energy Physics - Phenomenology · Physics 2011-04-15 Dubravko Klabucar , Dalibor Kekez

In present note the arguments in favour of future high statistical measurements of the formfactors that describe pi-meson decays into lepton-antilepton pair and photon are presented. It is shown that these formfactors Q^2 dependence…

High Energy Physics - Phenomenology · Physics 2007-05-23 N. B. Skachkov

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

We study the form factors of the low energy anomalous pion-2-photon and photon-3-pion processes in the nonlocal chiral quark model which incorporates the momentum dependence of the dynamical quark mass and realizes correctly the chiral…

High Energy Physics - Phenomenology · Physics 2009-11-07 Xiaoyuan Li , Yi Liao

The pion form factors of the QCD energy-momentum tensor (EMT) are studied in the instanton liquid model (ILM) of the QCD vacuum. In this approach the breaking of conformal symmetry is encoded in the form of stronger-than-Poisson…

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

The pion form factor is calculated using quenched twisted mass QCD with beta=6.0 and maximal twisting angle omega=pi/2. Two pion masses and several values of momentum transfer are considered. The momentum averaging procedure of Frezzotti…

High Energy Physics - Lattice · Physics 2009-11-10 Abdou M. Abdel-Rehim , Randy Lewis

We develop a relativistic quark model for pion structure, which incorporates the non-trivial structure of the vacuum of Quantum Chromodynamics as modelled by instantons. Pions are boundstates of quarks and the strong quark-pion vertex is…

High Energy Physics - Phenomenology · Physics 2009-10-31 I. V. Anikin , A. E. Dorokhov , A. E. Maximov , L. Tomio , V. Vento

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

Results on the electromagnetic form factors of the nucleon using twisted mass fermion configurations are presented. These include a gauge field ensemble simulated with two degenerate light quarks yielding a pion mass of around 130 MeV, as…

We compute the electromagnetic charged kaon form factor in the time-like region by employing a Poincar\'e covariant formalism of the Bethe-Salpeter equation to study quark-antiquark bound states in conjunction with the Schwinger-Dyson…

High Energy Physics - Phenomenology · Physics 2023-02-01 A. S. Miramontes , Adnan Bashir

We study the constraints arising on the expansion parameters c and d of the Pion electromagnetic form factor from the inclusion of pure space-like data and the phase of time-like data along with one space-like datum, using as input the…

High Energy Physics - Phenomenology · Physics 2009-07-22 Gauhar Abbas , B. Ananthanarayan , S. Ramanan

We present a quenched calculation of the form factors of the semileptonic weak decay $B \to \pi l \bar{\nu}$ with $O(1/m_Q)$ NRQCD heavy quark and Wilson light quark on a $16^3 \times 32$ lattice at $\beta=5.8$. The form factors are…

High Energy Physics - Lattice · Physics 2009-10-30 H. Matsufuru , S. Hashimoto , K-I. Ishikawa , T. Onogi , N. Yamada

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

A SU(2) effective lagrangian is extended to a $SU_{L}(3)\otimes SU_{R}(3)$ by including the vector and axial vector meson. With this effective lagrangian, electromagnetic form factors of charged pion and kaon are calculated. The…

Nuclear Theory · Physics 2009-10-31 Yun Chang Shin , Bong Soo Han , Myung Ki Cheoun , K. S Kim , Il-Tong Cheon