137 research outputs found
Phase-space distributions of nuclear short-range correlations
Nuclear short-range correlations (SRCs) induce high-momentum/high-energy
fluctuations in the nuclear medium. In order to assess their impact on nuclear
bulk properties, like nuclear radii and kinetic energies, it is instrumental to
determine how SRCs are distributed in phase space as this sheds light on the
connection between their appearance in coordinate and momentum space. Using the
lowest-order correlation operator approximation (LCA) to include SRC, we
compute two-dimensional nuclear Wigner quasiprobability distributions
to locate those phase-space regions that are most heavily impacted
by SRCs. The SRC-induced high-momentum components find their origin in a radial
range that is confined to the nuclear interior. Significant SRCs strength is
generated in the full momentum range
covered in this work, but below the Fermi momentum those are dwarfed by the
mean-field contributions. As an application of , we focus on the
radial dependence of the kinetic energy and the momentum dependence of the
radius for the symmetric nuclei C, Ca and the
asymmetric nucleus Ca. The kinetic energy almost doubles after including
SRCs, with the largest increase occurring in the nuclear interior fm. The momentum dependence of the teaches that the largest
contributions stem from fm, where the SRCs induce a
slight reduction of the order of a few percent. The SRCs systematically reduce
the Ca neutron skin by an amount that can be 10\%.Comment: 10 pages, 6 figures; revised version with updated Fig.1, matches
published versio
Color transparency and short-range correlations in exclusive pion photo- and electroproduction from nuclei
A relativistic and quantum mechanical framework to compute nuclear
transparencies for pion photo- and electroproduction reactions is presented.
Final-state interactions for the ejected pions and nucleons are implemented in
a relativistic eikonal approach. At sufficiently large ejectile energies, a
relativistic Glauber model can be adopted. At lower energies, the framework
possesses the flexibility to use relativistic optical potentials. The proposed
model can account for the color-transparency (CT) phenomenon and short-range
correlations (SRC) in the nucleus. Results are presented for kinematics
corresponding to completed and planned experiments at Jefferson Lab. The
influence of CT and SRC on the nuclear transparency is studied. Both the SRC
and CT mechanisms increase the nuclear transparency. The two mechanisms can be
clearly separated, though, as they exhibit a completely different dependence on
the hard scale parameter. The nucleon and pion transparencies as computed in
the relativistic Glauber approach are compared with optical-potential and
semi-classical calculations. The similarities in the trends and magnitudes of
the nuclear transparencies indicate that they are not subject to strong model
dependencies.Comment: 33 pages, 14 figure
Nuclear transparencies from photoinduced pion production
We present a relativistic and cross-section factorized framework for
computing nuclear transparencies extracted from A(\gamma,\pi N) reactions at
intermediate energies. The proposed quantummechanical model adopts a
relativistic extension to the multiple-scattering Glauber approximation to
account for the final state interactions of the ejected nucleon and pion. The
theoretical predictions are compared against the experimental ^4He(\gamma,p
\pi^-) data from Jefferson Lab. For those data, our results show no conclusive
evidence for the onset of mechanisms related to color transparency.Comment: 5 pages, 3 figure
Quasielastic contribution to antineutrino-nucleus scattering
We report on a calculation of cross sections for charged-current quasielastic
antineutrino scattering off C in the energy range of interest for the
MiniBooNE experiment. We adopt the impulse approximation (IA) and use the
nonrelativistic continuum random phase approximation (CRPA) to model the
nuclear dynamics. An effective nucleon-nucleon interaction of the Skyrme type
is used. We compare our results with the recent MiniBooNE antineutrino
cross-section data and confront them with alternate calculations. The CRPA
predictions reproduce the gross features of the shape of the measured
double-differential cross sections. The CRPA cross sections are typically
larger than those of other reported IA calculations but tend to underestimate
the magnitude of the MiniBooNE data. We observe that an enhancement of the
nucleon axial mass in CRPA calculations is an effective way of improving on the
description of the shape and magnitude of the double-differential cross
sections. The rescaling of is illustrated to affect the shape of the
double-differential cross sections differently than multinucleon effects beyond
the IA.Comment: 10 pages, 10 figures. Version published in Physical Review
Extracting the Mass Dependence and Quantum Numbers of Short-Range Correlated Pairs from A(e,e'p) and A(e,e'pp) Scattering
The nuclear mass dependence of the number of short-range correlated (SRC)
proton-proton (pp) and proton-neutron (pn) pairs in nuclei is a sensitive probe
of the dynamics of short-range pairs in the ground state of atomic nuclei. This
work presents an analysis of electroinduced single-proton and two-proton
knockout measurements off 12C, 27Al, 56Fe, and 208Pb in kinematics dominated by
scattering off SRC pairs. The nuclear mass dependence of the observed
A(e,e'pp)/12C(e,e'pp) cross-section ratios and the extracted number of pp- and
pn-SRC pairs are much softer than the mass dependence of the total number of
possible pairs. This is in agreement with a physical picture of SRC affecting
predominantly nucleon-nucleon pairs in a nodeless relative-S state of the
mean-field basis.Comment: 6 pages, 3 figure
QCD evolution of superfast quarks
Recent high-precision measurements of nuclear deep inelastic scattering at high x and moderate 6superfast region, in which the momentum fraction of the nucleon carried by its constituent quark is larger than the total fraction of the nucleon at rest, x\u3e1. We derive the leading-order QCD evolution equation for such quarks with the goal of relating the moderate-Q2 data to the two earlier measurements of superfast quark distributions at large 601.1 region is somewhat in the middle of the neutrino-nuclear and muon-nuclear scattering data
Relativistic eikonal description of A(p,pN) reactions
The authors present a relativistic and cross-section factorized framework for
computing quasielastic A(p,pN) observables at intermediate and high energies.
The model is based on the eikonal approximation and can accomodate both optical
potentials and the Glauber method for dealing with the initial- and final-state
interactions (IFSI). At lower nucleon energies, the optical-potential
philosophy is preferred, whereas at higher energies the Glauber method is more
natural. This versatility in dealing with the IFSI allows one to describe
A(p,pN) reactions in a wide energy range. Most results presented here use
optical potentials as this approach is argued to be the optimum choice for the
kinematics of the experiments considered in the present paper. The properties
of the IFSI factor, a function wherein the entire effect of the IFSI is
contained, are studied in detail. The predictions of the presented framework
are compared with two kinematically different experiments. First, differential
cross sections for quasielastic proton scattering at 1 GeV off 12C, 16O, and
40Ca target nuclei are computed and compared to data from PNPI. Second, the
formalism is applied to the analysis of a 4He(p,2p) experiment at 250 MeV. The
optical-potential calculations are found to be in good agreement with the data
from both experiments, showing the reliability of the adopted model in a wide
energy range.Comment: 34 pages, 14 figures, accepted for publication in Phys. Rev.
A review of implant provision for hypodontia patients within a Scottish referral centre
Background: Implant treatment to replace congenitally missing teeth often involves multidisciplinary input in a secondary care environment. High quality patient care requires an in-depth knowledge of treatment requirements.
Aim: This service review aimed to determine treatment needs, efficiency of service and outcomes achieved in hypodontia patients. It also aimed to determine any specific difficulties encountered in service provision, and suggest methods to overcome these.
Methods: Hypodontia patients in the Unit of Periodontics of the Scottish referral centre under consideration, who had implant placement and fixed restoration, or review completed over a 31 month period, were included. A standardised data collection form was developed and completed with reference to the patient's clinical record. Information was collected with regard to: the indication for implant treatment and its extent; the need for, complexity and duration of orthodontic treatment; the need for bone grafting and the techniques employed and indicators of implant success.
Conclusion: Implant survival and success rates were high for those patients reviewed. Incidence of biological complications compared very favourably with the literature
Precision Studies of QCD in the Low Energy Domain of the EIC
The manuscript focuses on the high impact science of the EIC with objective
to identify a portion of the science program for QCD precision studies that
requires or greatly benefits from high luminosity and low center-of-mass
energies. The science topics include (1) Generalized Parton Distributions, 3D
imagining and mechanical properties of the nucleon (2) mass and spin of the
nucleon (3) Momentum dependence of the nucleon in semi-inclusive deep inelastic
scattering (4) Exotic meson spectroscopy (5) Science highlights of nuclei (6)
Precision studies of Lattice QCD in the EIC era (7) Science of far-forward
particle detection (8) Radiative effects and corrections (9) Artificial
Intelligence (10) EIC interaction regions for high impact science program with
discovery potential. This paper documents the scientific basis for supporting
such a program and helps to define the path toward the realization of the
second EIC interaction region.Comment: 103 pages,47 figure
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