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Dispersion relations provide a powerful tool to analyse the electromagnetic form factors of the nucleon both in the space-like and time-like regions with constraints from other experiments, unitarity, and perturbative QCD. We give a brief…

High Energy Physics - Phenomenology · Physics 2007-05-23 H. -W. Hammer

Dispersion relations provide a powerful tool to describe the electromagnetic form factors of the nucleon both in the spacelike and timelike regions with constraints from unitarity and perturbative QCD. We give a brief introduction into…

High Energy Physics - Phenomenology · Physics 2014-11-17 H. -W. Hammer

Dispersion relations provide a powerful tool to analyse the electromagnetic form factors of the nucleon for all momentum transfers. Constraints from meson-nucleon scattering data, unitarity, and perturbative QCD can be included in a…

High Energy Physics - Phenomenology · Physics 2008-11-26 M. A. Belushkin , H. -W. Hammer , U. -G. Meißner

We argue that the description of meson-nucleon dynamics based on the boson-exchange approach, is compatible with the description of the nucleon as a soliton in the nonrelativistic limit. Our arguments are based on an analysis of the…

High Energy Physics - Theory · Physics 2009-10-22 Claudio Coriano' , Rajesh R. Parwani , Hidenaga Yamagishi , Ismail Zahed

Dispersion relations allow for a coherent description of the nucleon electromagnetic form factors measured over a large range of momentum transfer, $Q^2 \simeq 0 \ldots 35$ GeV$^2$. Including constraints from unitarity and perturbative QCD,…

High Energy Physics - Phenomenology · Physics 2008-11-26 P. Mergell , Ulf-G. Meißner , D. Drechsel

We extend the polaron variational treatment previously developed for the propagator to the case where one nucleon and $n$ external mesons are present. Using the particle representation of the scalar Wick-Cutkosky model this is done in…

Nuclear Theory · Physics 2009-09-02 A. W. Schreiber , R. Rosenfelder , C. Alexandrou

We study nucleon-nucleon ($NN$) scattering by applying the $N/D$ method in chiral perturbation theory up to next-to-next-to-leading (NNLO) order in the calculation of the imaginary part of the $NN$ partial-wave amplitudes along the…

Nuclear Theory · Physics 2014-02-13 J. A. Oller

The properties of nucleon-nucleon scattering inside dense nuclear matter are investigated. We use the relativistic Brueckner-Hartree-Fock model to determine on-shell and half off-shell in-medium transition amplitudes and cross sections. At…

Nuclear Theory · Physics 2009-11-07 C. Fuchs , Amand Faessler , M. El-Shabshiry

Dispersion relations provide a powerful tool to describe the low-energy structure of hadrons. We review the status of the strange vector form factors of the nucleon in dispersion theory. We also comment on open questions and the relation to…

High Energy Physics - Phenomenology · Physics 2007-05-23 H. -W. Hammer

I review the results of a recent dispersion--theoretical analysis of the nucleon electromagnetic form factors and comment on the strangeness form factors. The need for a better data basis at low, intermediate and large momentum transfer is…

High Energy Physics - Phenomenology · Physics 2007-05-23 Ulf-G. Meißner

Omnes dispersion relations make a connection between form factors for exclusive semileptonic decays and phase shifts in the corresponding elastic scattering channels. We describe two applications. In the first, we use lattice form factor…

High Energy Physics - Lattice · Physics 2008-11-26 J. M. Flynn , J. Nieves

A covariant formulation of spin-dependent deep-inelastic scattering from nuclei is presented. In the relativistic impulse approximation the inclusive nuclear cross section is described in terms of the amplitude for forward, virtual-photon…

Nuclear Theory · Physics 2008-11-26 G. Piller , W. Melnitchouk , A. W. Thomas

Analyses of high energy elastic pp and $\bar pp$ scattering data from CERN ISR and SPS Collider seem to provide strong evidence in favor of the gauged nonlinear sigma-model of the nucleon. This model describes the nucleon as a topological…

High Energy Physics - Phenomenology · Physics 2007-05-23 M. M. Islam

The dispersion relations in the real and imaginary parts of the meson self-energies are studied to check the consistency of the "renormalization" in cutoff field theory. It is shown that the dispersion relations are preserved by the…

Nuclear Theory · Physics 2007-05-23 K. Sakamoto , H. Kouno , A. Hasegawa , M. Nakano

We review the dispersion-theoretical analysis of the electromagnetic form factors of the nucleon. We emphasize in particular the role of unitarity and analyticity in the construction of the isoscalar and isovector spectral functions. We…

High Energy Physics - Phenomenology · Physics 2021-08-27 Yong-Hui Lin , Hans-Werner Hammer , Ulf-G. Meißner

Dispersive approaches provide model independent description of meson-meson scattering. We first review here the use of dispersion relations to obtain a model independent unitarization of Chiral Perturbation Theory amplitudes, that establish…

High Energy Physics - Phenomenology · Physics 2008-11-26 J. R. Pelaez

I discuss how dispersion relations can be used to analyse the nucleon electromagnetic form factors, with particular emphasis on the constraints from unitarity and pQCD. Results for nucleon radii, vector-meson couplings, the onset of pQCD…

High Energy Physics - Phenomenology · Physics 2009-10-30 Ulf-G. Meißner

The off-mass-shell behavior of the nucleon structure function, $F_2^N$, is studied within an approach motivated by the Sullivan model. Deep inelastic scattering on the nucleon is considered in the second order in the pion-nucleon coupling…

Nuclear Theory · Physics 2009-09-25 A. Yu. Umnikov , F. C. Khanna , L. P. Kaptari

We derive the general structure of the hadronic tensor required to describe deep-inelastic scattering from an off-shell nucleon within a covariant formalism. Of the large number of possible off-shell structure functions we find that only…

Nuclear Theory · Physics 2009-09-25 W. Melnitchouk , A. W. Schreiber , A. W. Thomas

Deep-inelastic scattering at low x and elastic vector meson production are considered on the basis of the off-shell extension of the s-channel unitarity. We discuss behavior of the structure function F_2(x,Q^2) at low x and the total…

High Energy Physics - Phenomenology · Physics 2007-05-23 S. M. Troshin , N. E. Tyurin
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