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The vacuum polarization due to chiral fermions on a 4--dimensional Euclidean lattice is calculated according to the overlap prescription. The fermions are coupled to weak and slowly varying background gauge and Higgs fields, and the…

High Energy Physics - Theory · Physics 2009-10-28 S. Randjbar--Daemi , J. Strathdee

An exact representation of the Euclidean fermion determinant in two dimensions for centrally symmetric, finite-ranged Abelian background fields is derived. Input data are the wave function inside the field's range and the scattering phase…

High Energy Physics - Theory · Physics 2009-11-10 M. P. Fry

In this talk, recent results are presented of calculations of electromagnetic form factors of hadrons in the framework of two quantum field theories (QFT), (a) Dual-Large $N_c$ QCD (Dual-$QCD_\infty$) for the pion, proton, and…

High Energy Physics - Phenomenology · Physics 2008-11-26 C. A. Dominguez

We investigate the radiative corrections on spin polarization of relativistic fermions induced by vortical fields in thermal-equilibrium QCD matter at weak coupling. Such corrections stem from the self-energy gradients in quantum kinetic…

High Energy Physics - Phenomenology · Physics 2025-03-18 Shuo Fang , Shi Pu , Di-Lun Yang

We study the form factors of vector mesons using a covariant fermion field theory model in $(3+1)$ dimensions. Performing a light-front calculation in the $q^+ =0$ frame in parallel with a manifestly covariant calculation, we note the…

High Energy Physics - Phenomenology · Physics 2009-11-07 Bernard L. G. Bakker , Ho-Meoyng Choi , Chueng-Ryong Ji

In this work, the electromagnetic and gravitational form factors of a spin-$3/2$ particle, $\Delta$ resonance, are simultaneously calculated with the help of a relativistic covariant quark-diquark approach. The two kinds of form factors are…

High Energy Physics - Phenomenology · Physics 2022-01-24 Dongyan Fu , Bao-Dong Sun , Yubing Dong

The electromagnetic form factors have attracted lot of theoretical and experimental attention recently as they encode extensive information on the internal structure of the hadron. An understanding of the form factors is necessary to…

High Energy Physics - Phenomenology · Physics 2011-08-02 Harleen Dahiya , Neetika Sharma

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 electromagnetic form factors of the nucleon are calculated at order $q^4$ in the relativistic formulation of baryon chiral perturbation theory. In order to obtain a consistent power counting for the renormalized diagrams we make use of…

Nuclear Theory · Physics 2009-11-10 Thomas Fuchs , Jambul Gegelia , Stefan Scherer

We compute the magnetic field-induced modifications to the boson self-coupling and the boson-fermion coupling, in the static limit, using an effective model of QCD, the linear sigma model with quarks. The former is computed for arbitrary…

High Energy Physics - Phenomenology · Physics 2021-01-04 Alejandro Ayala , José Luis Hernández , L. A. Hernández , Ricardo L. S. Farias , R. Zamora

Using dispersion theory, the electromagnetic Sigma-to-Lambda transition form factors are expressed as the product of the pion electromagnetic form factor and the $\Sigma\bar{\Lambda}\to\pi\pi$ scattering amplitudes with the latter estimated…

High Energy Physics - Phenomenology · Physics 2023-04-05 Yong-Hui Lin , Hans-Werner Hammer , Ulf-G. Meißner

The rotation of polarization occurs for light interacting with chiral materials. It requires the light states with opposite chiralities interact differently with the materials. We demonstrate analogous rotation of polarization also exists…

High Energy Physics - Phenomenology · Physics 2021-06-03 Defu Hou , Shu Lin

The electromagnetic form factors of light and heavy pseudoscalar mesons are calculated within two covariant constituent-quark models, a light-front and a dispersion relation approach. We investigate the details and physical origins of the…

High Energy Physics - Phenomenology · Physics 2011-08-31 B. El-Bennich , J. P. B. C. de Melo , B. Loiseau , J. -P. Dedonder , T. Frederico

The charge, magnetic and quadrupole form factors of vector mesons and the charge form factor of pseudo-scalar mesons are calculated in quenched lattice QCD. The charge radii and magnetic moments are derived. The quark sector contributions…

High Energy Physics - Lattice · Physics 2010-03-04 B. G. Lasscock , J. Hedditch , D. B. Leinweber , A. G. Williams

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

Effects due to fermion-vacuum polarization by an external static magnetic field are considered in a two-dimensional noncompact curved space with a nontrivial topology. An expression for the vacuun angular momentum is obtained. Like the…

High Energy Physics - Theory · Physics 2007-05-23 Yu. A. Sitenko , D. G. Rakityansky

Continuing the study of boundary BCFW recursion relation of tree level amplitudes initiated in \cite{Feng:2009ei}, we consider boundary contributions coming from fermion pair deformation. We present the general strategy for these boundary…

High Energy Physics - Theory · Physics 2012-01-09 Bo Feng , Zhibai Zhang

We derive the generalized chiral kinetic equations which are applicable to the fermions with arbitrary mass. We show how the dynamical magnetic-moment distribution function could lead to spin polarization and electric charge separation. We…

High Energy Physics - Phenomenology · Physics 2023-08-16 Shu-Xiang Ma , Jian-Hua Gao

We investigate in-medium polarization effects of the fermion and antifermion pairs at finite temperature and density in strong magnetic fields within the lowest Landau level approximation. Inspecting the integral representation of the…

High Energy Physics - Phenomenology · Physics 2022-09-28 Koichi Hattori , Kazunori Itakura

We develop a unitarity approach to consider the final state interaction corrections to the tree level graphs calculated from Chiral Perturbation Theory ($\chi PT$) allowing the inclusion of explicit resonance fields. The method is discussed…

High Energy Physics - Phenomenology · Physics 2009-10-31 J. A. Oller , E. Oset , J. E. Palomar