29 research outputs found
Neural Network Parameterizations of Electromagnetic Nucleon Form Factors
The electromagnetic nucleon form-factors data are studied with artificial
feed forward neural networks. As a result the unbiased model-independent
form-factor parametrizations are evaluated together with uncertainties. The
Bayesian approach for the neural networks is adapted for chi2 error-like
function and applied to the data analysis. The sequence of the feed forward
neural networks with one hidden layer of units is considered. The given neural
network represents a particular form-factor parametrization. The so-called
evidence (the measure of how much the data favor given statistical model) is
computed with the Bayesian framework and it is used to determine the best form
factor parametrization.Comment: The revised version is divided into 4 sections. The discussion of the
prior assumptions is added. The manuscript contains 4 new figures and 2 new
tables (32 pages, 15 figures, 2 tables
Probing superfast quarks in nuclei through dijet production at the LHC
We investigate dijet production from proton-nucleus collisions at the Large
Hadron Collider (LHC) as a means for observing superfast quarks in nuclei with
Bjorken . Kinematically, superfast quarks can be identified through
directly measurable jet kinematics. Dynamically, their description requires
understanding several elusive properties of nuclear QCD, such as nuclear forces
at very short distances, as well as medium modification of parton distributions
in nuclei. In the present work, we develop a model for nuclear parton
distributions at large in which the nuclear dynamics at short distance
scales are described by two- and three-nucleon short range correlations (SRCs).
Nuclear modifications are accounted for using the color screening model, and an
improved description of the EMC effect is reached by using a structure function
parametrization that includes higher-twist contributions. We apply QCD
evolution at the leading order to obtain nuclear parton distributions in the
kinematic regime of the LHC, and based on the obtained distributions calculate
the cross section for dijet production. We find not only that superfast quarks
can be observed at the LHC, but also that they provide sensitivity to the
practically unexplored three-nucleon SRCs in nuclei. Additionally, the LHC can
extend our knowledge of the EMC effect to large where higher-twist
effects are negligible.Comment: 44 pages, 17 figures, final version to be published in EJP
The deuteron: structure and form factors
A brief review of the history of the discovery of the deuteron in provided.
The current status of both experiment and theory for the elastic electron
scattering is then presented.Comment: 80 pages, 33 figures, submited to Advances in Nuclear Physic
Ratios of 15N/12C and 4He/12C inclusive electroproduction cross sections in the nucleon resonance region
The (W,Q2)-dependence of the ratio of inclusive electron scattering cross
sections for 15N/12C was determined in the kinematic range 0.8<W<2 GeV and
0.2<Q2<1 GeV2 using 2.285 GeV electrons and the CLAS detector at Jefferson Lab.
The ratios exhibit only slight resonance structure, in agreement with a simple
phenomenological model and an extrapolation of DIS ratios to low Q2. Ratios of
4He/12C using 1.6 to 2.5 GeV electrons were measured with very high statistical
precision, and were used to correct for He in the N and C targets. The (W,Q2)
dependence of the 4He/12C ratios is in good agreement with the phenomenological
model, and exhibit significant resonance structure centered at W=0.94, 1.23 and
1.5 GeV.Comment: 13 pages, 2 figures. Significantly shortened version. Results
unchanged. Small additions for Phys. Rev.
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