The Experts below are selected from a list of 282 Experts worldwide ranked by ideXlab platform
Bastian Kubis - One of the best experts on this subject based on the ideXlab platform.
-
Charge-symmetry-breaking nucleon Form Factors
Hyperfine Interactions, 2011Co-Authors: Bastian KubisAbstract:A quantitative understanding of charge-symmetry breaking is an increasingly important ingredient for the extraction of the nucleon’s strange vector Form Factors. We review the theoretical understanding of the charge-symmetry-breaking Form Factors, both for single nucleons and for ^4He.
-
Isospin violation in the vector Form Factors of the nucleon
Physical Review C, 2006Co-Authors: Bastian Kubis, Randy LewisAbstract:A quantitative understanding of isospin violation is an increasingly important ingredient for the extraction of the nucleon's strange vector Form Factors from experimental data. We calculate the isospin violating electric and magnetic Form Factors in chiral perturbation theory to leading and next-to-leading order respectively, and we extract the low-energy constants from resonance saturation. Uncertainties are dominated largely by limitations in the current knowledge of some vector meson couplings. The resulting bounds on isospin violation are sufficiently precise to be of value to on-going experimental studies of the strange Form Factors.
-
BARYON Form Factors
Physics Letters B, 1999Co-Authors: Bastian Kubis, T. R. Hemmert, Ulf-g. MeißnerAbstract:Abstract We calculate the Form Factors of the baryon octet in the framework of heavy baryon chiral perturbation theory. The calculated charge radius of the Σ− is in agreement with recent measurements from CERN and Fermilab. We show that kaon loop effects can play a significant role in the neutron electric Form factor. Furthermore, we derive generalized Caldi–Pagels relations between various charge radii which are free of chiral loop effects.
Craig D. Roberts - One of the best experts on this subject based on the ideXlab platform.
-
survey of nucleon electromagnetic Form Factors
Few-body Systems, 2009Co-Authors: Craig D. Roberts, I C Cloe, Gerno Eichma, Thomas KlahAbstract:A dressed-quark core contribution to nucleon electromagnetic Form Factors is calculated. It is defined by the solution of a Poincare covariant Faddeev equation in which dressed-quarks provide the elementary degree of freedom and correlations between them are expressed via diquarks. The nucleon-photon vertex involves a single parameter; namely, a diquark charge radius. It is argued to be commensurate with the pion’s charge radius. A comprehensive analysis and explanation of the Form Factors is built upon this foundation. A particular feature of the study is a separation of Form factor contributions into those from different diagram types and correlation sectors, and subsequently a flavour separation for each of these. Amongst the extensive body of results that one could highlight are: \({r_1^{n,u} > r_1^{n,d}}\) , owing to the presence of axial-vector quark-quark correlations; and for both the neutron and proton the ratio of Sachs electric and magnetic Form Factors possesses a zero.
-
covariance dynamics and symmetries and hadron Form Factors
Exclusive Reactions at High Momentum Transfer, 2008Co-Authors: M S Bhagwat, I. C. Cloët, Craig D. RobertsAbstract:We summarize applications of Dyson-Schwinger equations to the theory and phenomenology of hadrons. Some exact results for pseudoscalar mesons are highlighted with details relating to the U{sub A}(1) problem. We describe inferences from the gap equation relating to the radius of convergence for expansions of observables in the current-quark mass. We recapitulate upon studies of nucleon electromagnetic Form Factors, providing a comparison of the ln-weighted ratios of Pauli and Dirac Form Factors for the neutron and proton.
-
Nucleon electromagnetic Form Factors
Journal of Physics G: Nuclear and Particle Physics, 2007Co-Authors: John Arrington, Craig D. Roberts, James ZanottiAbstract:Elastic electromagnetic nucleon Form Factors have long provided vital inFormation about the structure and composition of these most basic elements of nuclear physics. The Form Factors are a measurable and physical manifestation of the nature of the nucleons' constituents and the dynamics that binds them together. Accurate Form factor data obtained in recent years using modern experimental facilities has spurred a significant reevaluation of the nucleon and pictures of its structure; e.g., the role of quark orbital angular momentum, the scale at which perturbative QCD effects should become evident, the strangeness content, and meson-cloud effects. We provide a succinct survey of the experimental studies and theoretical interpretation of nucleon electromagnetic Form Factors.
-
Regarding Proton Form Factors
Few-Body Systems, 2003Co-Authors: Jacques Bloch, Andreas Krassnigg, Craig D. RobertsAbstract:The proton’s elastic electromagnetic Form Factors are calculated using an ansatz for the nucleon’s Poincare covariant Faddeev amplitude that only retains scalar diquark correlations. A spectator approximation is employed for the current. On the domain of q2 accessible in modern precision experiments these Form Factors are a sensitive probe of nonperturbative strong interaction dynamics. The ratio of Pauli and Dirac Form Factors can provide realistic constraints on models of the nucleon and thereby assist in developing an understanding of nucleon structure.
H. Schmieden - One of the best experts on this subject based on the ideXlab platform.
-
Form Factors of the nucleon
Nuclear Physics A, 2004Co-Authors: H. SchmiedenAbstract:Abstract Elastic Form Factors are related to the low energy structure of composite particles. Recent double polarization experiments precisely determined proton and neutron elastic Form Factors.
-
Electromagnetic Form Factors of the neutron
AIP Conference Proceedings, 2002Co-Authors: H. SchmiedenAbstract:Elastic Form Factors provide inFormation about the charge and current distribution inside proton and neutron. Recent coincidence experiments significantly improved our knowledge of both the electric and magnetic neutron Form Factors. The results from the 3He(e,e′n), D(e,e′n) and D(e,e′n) double polarization experiments indicate that the neutron electric Form factor is almost a factor of two larger than previously assumed from D(e,e′) elastic scattering.
J. E. Palomar - One of the best experts on this subject based on the ideXlab platform.
-
Pion and kaon vector Form Factors and some applications
AIP Conference Proceedings, 2002Co-Authors: J. E. PalomarAbstract:The pion and kaon coupled-channel vector Form Factors are described by making use of the resonance chiral Lagrangian results together with a suitable unitarization method in order to take care of the final state interactions. A very good reproduction of experimental data is accomplished for the vector Form Factors up to s⩽1.2 GeV. We then apply these Form Factors to calculate the width of τ decay to two pions and to two kaons and also to evaluate the contribution of these mesons to the anomalous magnetic moment of the muon.
-
Pion and kaon vector Form Factors
Physical Review D, 2001Co-Authors: José Antonio Oller, Eulogio Oset, J. E. PalomarAbstract:We develop a unitarity approach to consider the final state interaction corrections to the tree level graphs calculated from chiral perturbation theory ( xPT) allowing the inclusion of explicit resonance fields. The method is discussed considering the coupled channel pion and kaon vector Form Factors. These Form Factors are then matched with the one loop xPT results. A very good description of experimental data is accomplished for the vector Form Factors up to As
-
pion and kaon vector Form Factors
Physical Review D, 2001Co-Authors: José Antonio Oller, Eulogio Oset, J. E. PalomarAbstract:We develop a unitarity approach to consider the final state interaction corrections to the tree level graphs calculated from chiral perturbation theory ( xPT) allowing the inclusion of explicit resonance fields. The method is discussed considering the coupled channel pion and kaon vector Form Factors. These Form Factors are then matched with the one loop xPT results. A very good description of experimental data is accomplished for the vector Form Factors up to As<1.2 GeV beyond which multiparticle states play a non-negligible role. For the P-wave pp phase shifts the agreement with data stands even higher up to As<1.5 GeV. We also consider the isospin breaking effects due to the v-r mixing as a perturbation to the previous results. In addition the low and resonance energy regions are discussed in detail and for the Former a comparison with one and two loop xPT is made showing a remarkable coincidence with the two loop xPT results.
Donal Day - One of the best experts on this subject based on the ideXlab platform.
-
The Nucleon Elastic Form Factors
Nuclear Physics A, 2005Co-Authors: Donal DayAbstract:The nucleon elastic Form Factors are of fundamental interest, provide a unique testing ground for QCD motivated models of nucleon structure and are of critical importance to our understanding of the electromagnetic properties of nuclei. Even after an experimental effort spanning nearly 50 years the nucleon Form Factors are still the subject of active investigation. Advances in polarized beams, polarized targets and recoil polarimetry have been exploited over the last decade to produce an important and precise set of data. I review the status of the experimental efforts to measure the nucleon elastic Form Factors.