2,669 research outputs found
A pure S-wave covariant model for the nucleon
Using the manifestly covariant spectator theory, and modeling the nucleon as
a system of three constituent quarks with their own electromagnetic structure,
we show that all four nucleon electromagnetic form factors can be very well
described by a manifestly covariant nucleon wave function with zero orbital
angular momentum. Since the concept of wave function depends on the formalism,
the conclusions of light-cone theory requiring nonzero angular momentum
components are not inconsistent with our results. We also show that our model
gives a qualitatively correct description of deep inelastic scattering,
unifying the phenomenology at high and low momentum transfer. Finally we review
two different definitions of nuclear shape and show that the nucleon is
spherical in this model, regardless of how shape is defined.Comment: 20 pages and 10 figures; greatly expanded version with new fits and
discussion of DIS; similar to published versio
Neutron electric form factor at large momentum transfer
Based on the recent, high precision data for elastic electron scattering from
protons and deuterons, at relatively large momentum transfer , we
determine the neutron electric form factor up to GeV. The values
obtained from the data (in the framework of the nonrelativistic impulse
approximation) are larger than commonly assumed and are in good agreement with
the Gari-Kr\"umpelmann parametrization of the nucleon electromagnetic form
factors.Comment: 11 pages 2 figure
High energy inelastic electron hadron scattering, in peripheral kinematics. Sum rules for hadron form factors
Relations between differential cross section for inelastic scattering of
electrons on hadrons and hadron form factors (sum rules) are derived on the
basis of analytical properties of heavy photon forward Compton scattering on
hadrons. Sum rules relating the slope of form-factors at zero momentum transfer
and anomalous magnetic moments of hadrons with some integrals on
photo-production on a hadrons is obtained as well. To provide the convergence
of these integrals we construct differences of individual sum rules for
different hadrons. Universal interaction of Pomeron with nucleons is assumed.
We derive the explicit formulae for processes of electro-production on proton
and light isobar nuclei. Sudakov's parametrization of momenta, for peripheral
kinematics relevant here, is used. The light-cone form of differential cross
sections is also discussed. The accuracy of sum rules estimated in frames of
point-like hadrons and it is shown to be at the level of precision achievable
by experiments. Suggestions and predictions for future experiments are also
given.Comment: 18 pages, 5 figure
Target normal spin asymmetry and charge asymmetry for elastic scattering and the crossed processes
Two kinds of asymmetry arise from the interference of the Born amplitude and
the box-type amplitude corresponding to two virtual photons exchange, namely
charge-odd and one spin asymmetries. In case of unpolarized particles the
charge-odd correlation is calculated. It can be measured in combination of
electron muon and positron muon scattering experiments. The forward-backward
asymmetry is the corresponding quantity which can be measured for the crossed
processes. In the case of polarized muon the one-spin asymmetry for
annihilation and scattering channels has been calculated. The additional
structure function arising from the interference is shown to suffer from
infrared divergencies. The background due to electroweak interaction is
discussed.Comment: 19 pages, 5 figure
Effects of Capsaicin on the Hemodynamic Responses to Handgrip Exercise: Potential Influence of Race
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On radiative corrections for unpolarized electron proton elastic scattering
A statistical analysis of the elastic unpolarized electron proton scattering
data shows that, at large momentum transfer, the size and the
dependence of the radiative corrections, as traditionally calculated and
applied, may induce large correlations of the parameters of the Rosenbluth fit,
which prevent a correct extraction of the electric proton form factor. Using
the electron QED structure (radiation) function approach the cross section of
elastic electron-proton scattering in leading and next-to leading
approximations is calculated and expressed as a correction to the Born cross
section, which is different for the electric and the magnetic contribution.
When properly applied to the data, it may give the solution to the problem of
the discrepancy of the polarized and unpolarized results on electron proton
scattering.Comment: 11 pagex, 5 figure
Constraining the Hadronic Contributions to the Muon Anomalous Magnetic Moment
The mini-proceedings of the Workshop on "Constraining the hadronic
contributions to the muon anomalous magnetic moment" which included the "13th
meeting of the Radio MonteCarLow WG" and the "Satellite meeting R-Measurements
at BES-III" held in Trento from April 10th to 12th, 2013, are presented. This
collaboration meeting aims to bring together the experimental e+e- collider
communities from BaBar, Belle, BESIII, CMD2, KLOE, and SND, with theorists
working in the fields of meson transitions form factors, hadronic contributions
to (g-2)_\mu and effective fine structure constant, and development of Monte
Carlo generator and Radiative Corrections for precision e+e- and tau physics.Comment: 45 pages, 17 contributions. Editors: P. Masjuan and G. Venanzon
Heparin-induced lipoprotein precipitation apheresis in dyslipidemic patients: A multiparametric assessment
Low-density lipoprotein (LDL) apheresis (LA) selectively eliminates lipoproteins containing apolipoprotein B 100 (ApoB100) on patients affected by severe dyslipidemia. In addition to lowering lipids, LA is thought to exert pleiotropic effects altering a number of other compounds associated with atherosclerosis, such as pro- and anti-inflammatory cytokines or pro-thrombotic factors
Dynamic thiol/disulphide homeostasis before and after radical prostatectomy in patients with prostate cancer
Thiol groups are important anti-oxidants and essential molecules protecting organism against the harmful effects of reactive oxygen species (ROS). The aim of our study is to evaluate thiol–disulphide homeostasis with a novel recent automated method in patients with localized prostate cancer (PC) before and six months after radical prostatectomy (RP). 18 patients with PC and 17 healthy control subjects were enrolled into the study. Blood samples were collected from the controls subjects and patients before and six months after RP. Thiol–disulphide homeostasis was determined using a recently developed novel method. Prostate-specific antigen (PSA), albumin, total protein, total thiol, native thiol, disulphide and total antioxidant status (TAS) were measured and compared between the groups. Native thiol, total thiol and TAS levels were significantly higher in the control group than the patients before RP (p <.001). There was a non-significant increase in the native thiol, total thiol and TAS levels in the patients six months after RP in comparison to the levels before RP (p values.3,.3 and.09, respectively). We found a significant negative correlation between PSA and thiol levels. Our study demonstrated that the decreased thiol and TAS levels weakened anti-oxidant defence mechanism in the patients with PC as indicated. Increased oxidative stress in prostate cancer patients may cause metabolic disturbance and have a role in the aetiopathogenesis of prostate cancer
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