5,905 research outputs found
Relativistic Hamiltonians in many-body theories
We discuss the description of a many-body nuclear system using Hamiltonians
that contain the nucleon relativistic kinetic energy and potentials with
relativistic corrections. Through the Foldy-Wouthuysen transformation, the
field theoretical problem of interacting nucleons and mesons is mapped to an
equivalent one in terms of relativistic potentials, which are then expanded at
some order in 1/m_N. The formalism is applied to the Hartree problem in nuclear
matter, showing how the results of the relativistic mean field theory can be
recovered over a wide range of densities.Comment: 14 pages, uses REVTeX and epsfig, 3 postscript figures; a postscript
version of the paper is available by anonymous ftp at
ftp://carmen.to.infn.it/pub/depace/papers/951
On the role of the effective interaction in quasi-elastic electron scattering calculations
The role played by the effective residual interaction in the transverse
nuclear response for quasi-free electron scattering is discussed. The analysis
is done by comparing different calculations performed in the Random--Phase
Approximation and Ring Approximation frameworks. The importance of the exchange
terms in this energy region is investigated and the changes on the nuclear
responses due to the modification of the interaction are evaluated. The
calculated quasi-elastic responses show clear indication of their sensibility
to the details of the interaction and this imposes the necessity of a more
careful study of the role of the different channels of the interaction in this
excitation region.Comment: 16 pages, 4 Postscript figure
New Measurements of Nucleon Structure Functions from the CCFR/NuTeV Collaboration
We report on the extraction of the structure functions F_2 and Delta xF_3 =
xF_3nu-xF_3nubar from CCFR neutrino-Fe and antineutrino-Fe differential cross
sections. The extraction is performed in a physics model independent (PMI) way.
This first measurement for Delta xF_3, which is useful in testing models of
heavy charm production, is higher than current theoretical predictions. The F_2
(PMI) values measured in neutrino and muon scattering are in good agreement
with the predictions of Next to Leading Order PDFs (using massive charm
production schemes), thus resolving the long-standing discrepancy between the
two sets of data.Comment: 5 pages. Presented by Arie Bodek at the CIPNAP2000 Conference, Quebec
City, May 200
Superscaling and Neutral Current Quasielastic Neutrino-Nucleus Scattering beyond the Relativistic Fermi Gas Model
The superscaling analysis is extended to include quasielastic (QE) scattering
via the weak neutral current of neutrinos and antineutrinos from nuclei. The
scaling function obtained within the coherent density fluctuation model (used
previously in calculations of QE inclusive electron and charge-changing (CC)
neutrino scattering) is applied to neutral current neutrino and antineutrino
scattering with energies of 1 GeV from C with a proton and neutron
knockout (u-channel inclusive processes). The results are compared with those
obtained using the scaling function from the relativistic Fermi gas model and
the scaling function as determined from the superscaling analysis (SuSA) of QE
electron scattering.Comment: 10 pages, 6 figures, published in Phys. Rev.
Superscaling analyses, lepton scattering and nucleon momentum distributions in nuclei
It is shown that superscaling is due to the high-momentum tail of the nucleon momentum distribution n(k) which is similar for all nuclei and is caused by the short-range and tensor nucleon-nucleon correlations. It is pointed out also that superscaling gives information about the general power-law asymptotics of n(k) and the nucleon-nucleon forces in the nuclear medium. The Coherent Density Fluctuation Model (CDFM) is used to calculate the total, longitudinal and transverse scaling functions on the basis of the hadronic tensor and the corresponding response functions in the RFG model. The results show a good agreement with the data and superscaling of the scaling function f(ψ′) for negative ψ′ including the region ψ′ < −1, where the RFGmodel fails. The CDFM scaling functions are used to calculate the cross sections of the quasielastic (QE) electron scattering on nuclei in the mass region 12 < A < 208, as well as charge-changing and neutral current neutrino (antineutrino) scattering on 12C in the QE and the -resonance regions at energies from 1 to 2 GeV
Superscaling and Charge-Changing Neutrino Scattering from Nuclei in the -Region beyond the Relativistic Fermi Gas Model
The superscaling analysis using the scaling function obtained within the
coherent density fluctuation model is extended to calculate charge-changing
neutrino and antineutrino scattering on C at energies from 1 to 2 GeV
not only in the quasielastic but also in the delta excitation region. The
results are compared with those obtained using the scaling functions from the
relativistic Fermi gas model and from the superscaling analysis of inclusive
scattering of electrons from nuclei.Comment: 9 pages, 8 figures, accepted for publication in Physical Review
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