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A numerical investigation of time-separated charge overlap measurements is carried out for the pion in the context of lattice QCD using smeared Wilson fermions. The evolution of the charge distribution function is examined and the expected…

High Energy Physics - Lattice · Physics 2009-10-22 Walter Wilcox

We consider the electromagnetic and transition pion form factors. Using dispersion relations we simultaneously describe both the hadronic, time-like region and the asymptotic region of large energy-momentum transfer. For the latter we…

High Energy Physics - Phenomenology · Physics 2011-06-28 Mikhail Gorchtein , Peng Guo , Adam P. Szczepaniak

The hadronic vacuum polarization can be determined from the vector correlator in a mixed time-momentum representation. We explicitly calculate the disconnected contribution to the vector correlator, both in the $N_f = 2$ theory and with an…

High Energy Physics - Lattice · Physics 2014-12-01 Anthony Francis , Vera Gülpers , Benjamin Jäger , Harvey Meyer , Georg von Hippel , Hartmut Wittig

We present our calculations of the electromagnetic form factor of pions. We explore the properties of pion form factor at momentum transfer larger than previous studies by including more combinations of source and sink momenta and using…

High Energy Physics - Lattice · Physics 2010-12-13 Pai-hsien Jennifer Hsu , George T. Fleming

We study the reaction $e^+e^-\to\pi^0\gamma$ based on a dispersive representation of the underlying $\pi^0\to\gamma\gamma^*$ transition form factor. As a first application, we evaluate the contribution of the $\pi^0\gamma$ channel to the…

High Energy Physics - Phenomenology · Physics 2020-10-30 Bai-Long Hoid , Martin Hoferichter , Bastian Kubis

We present a dispersion relation in the pion-mass squared, which static quantities (nucleon mass, magnetic moment, etc.) obey under the assumption of analyticity in the entire complex $m_\pi^2$ plane modulo a cut at negative $m_\pi^2$…

High Energy Physics - Phenomenology · Physics 2014-11-20 Tim Ledwig , Vladimir Pascalutsa , Marc Vanderhaeghen

The behaviour of the pion transition form factor for the process $\gamma^\star\gamma \to \pi^0$ and $\gamma^\star\gamma^\star\to \pi^0$ at space-like values of photon momenta is estimated within the nonlocal covariant quark-meson model. The…

High Energy Physics - Phenomenology · Physics 2007-05-23 A. E. Dorokhov

Baryon form factors can be analyzed in a largely model-independent fashion in terms of two complementary approaches. These are chiral perturbation theory and dispersion relations. I review the status of dispersive calculations of the…

High Energy Physics - Phenomenology · Physics 2009-10-31 Ulf-G. Meißner

The first three coefficients of the Taylor's series expansion of the vector pion form factor as a function of the momentum transfer are evaluated using experimental data on the pion form factor and the P-wave pi pi phase shifts. The real…

High Energy Physics - Phenomenology · Physics 2007-05-23 Tran N. Truong

We present an extended analysis of the data for the pion-photon transition form factor from different experiments, CELLO, CLEO, and BaBar, and discuss various theoretical approaches which try to reason from them. We focus on the divergent…

High Energy Physics - Phenomenology · Physics 2013-01-03 N. G. Stefanis , Alexander P. Bakulev , S. V. Mikhailov , A. V. Pimikov

The electromagnetic form factor of the pion is calculated within the use of functional formalism. We develop integral representation for the minimal set of Standard Model Green's functions and derive the dispersion relation for the form…

High Energy Physics - Phenomenology · Physics 2022-09-30 Vladimir Sauli

The precision with which hadronic vacuum polarization (HVP) is obtained determines how accurately important observables, such as the muon anomalous magnetic moment, a_\mu, or the low-energy running of the electromagnetic coupling, \alpha,…

We extend a recent numerical calculation of the pion electromagnetic form factor F_\pi (Q^2) in holographic QCD to study two important issues regarding the behavior of fields in the bulk. First, we show that using a chiral symmetry-breaking…

High Energy Physics - Phenomenology · Physics 2008-11-26 Herry J. Kwee , Richard F. Lebed

We investigate threshold pion photoproduction in the framework of heavy baryon chiral perturbation theory. We give the expansion of the electric dipole amplitude $E_{0+}$ to three orders in $\mu$, the ratio of the pion to nucleon mass, and…

High Energy Physics - Phenomenology · Physics 2009-09-25 V. Bernard , N. Kaiser , Ulf-G. Meißner

I review recent estimates of the non-perturbative hadronic vacuum polarization contributions. Since these at present can only be evaluated in terms of experimental data of limited precision, the related uncertainties pose a serious…

High Energy Physics - Phenomenology · Physics 2009-11-10 F. Jegerlehner

Investigation of the spacelike and timelike electromagnetic form factors of hadrons, within a relativistic microscopical model characterized by a small set of hypothesis, could shed light on the components of hadron states beyond the…

High Energy Physics - Phenomenology · Physics 2008-11-26 J. P. B. C. de Melo , T. Frederico , E. Pace , S. Pisano , G. Salme'

In my talk I discuss the theoretical and experimental status of the pion distribution amplitude (DA). I show that the QCD sum rule method with nonlocal condensates (NLC) for the pion DA gives us admissible sets (bunches) of DAs for each…

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

Recent experimental data on tau decays are used to reconstruct the difference in hadronic spectral densities with vector and axial-vector quantum numbers. The saturation of Das-Mathur-Okubo and Weinberg sum rules is studied. Two methods of…

High Energy Physics - Phenomenology · Physics 2011-07-19 V. Kartvelishvili , M. Margvelashvili , G. Shaw

Clear windows onto emergent hadron mass (EHM) and modulations thereof by Higgs boson interactions are provided by observable measures of pion and kaon structure, many of which are accessible via generalised parton distributions (GPDs).…

High Energy Physics - Phenomenology · Physics 2022-01-26 Khepani Raya , Zhu-Fang Cui , Lei Chang , Jose-Manuel Morgado , Craig D. Roberts , Jose Rodriguez-Quintero