30,651 research outputs found
Masses, Deformations and Charge Radii--Nuclear Ground-State Properties in the Relativistic Mean Field Model
We perform a systematic study of the ground-state properties of all the
nuclei from the proton drip line to the neutron drip line throughout the
periodic table employing the relativistic mean field model. The TMA parameter
set is used for the mean-field Lagrangian density, and a state-dependent BCS
method is adopted to describe the pairing correlation. The ground-state
properties of a total of 6969 nuclei with and from the
proton drip line to the neutron drip line, including the binding energies, the
separation energies, the deformations, and the rms charge radii, are calculated
and compared with existing experimental data and those of the FRDM and HFB-2
mass formulae. This study provides the first complete picture of the current
status of the descriptions of nuclear ground-state properties in the
relativistic mean field model. The deviations from existing experimental data
indicate either that new degrees of freedom are needed, such as triaxial
deformations, or that serious effort is needed to improve the current
formulation of the relativistic mean field model.Comment: 16 pages, 5 figures, to appear in Progress of Theoretical Physic
A systematic study of neutron magic nuclei with N = 8, 20, 28, 50, 82, and 126 in the relativistic mean field theory
We perform a systematic study of all the traditional neutron magic nuclei
with = 8, 20, 28, 50, 82, and 126, from the neutron drip line to the proton
drip line. We adopt the deformed relativistic mean field (RMF) theory as our
framework and treat pairing correlations by a simple BCS method with a
zero-range -force. Remarkable agreement with the available experimental
data is obtained for the binding energies, the two- and one-proton separation
energies, and the nuclear charge radii. The calculated nuclear deformations are
compared with the available experimental data and the predictions of the FRDM
mass formula and the HFBCS-1 mass formula. We discuss, in particular, the
appearance of sub-shell magic nuclei by observing irregular behavior in the
two- and one-proton separation energies.Comment: the version to appear in Journal of Physics G; more references adde
Relativistic mean field theory for deformed nuclei with pairing correlations
We develop a relativistic mean field (RMF) description of deformed nuclei
with the pairing correlations in the BCS approximation. The treatment of the
pairing correlations for nuclei with the Fermi surface being close to the
threshold of unbound states needs a special attention. To this end, we take the
delta function interaction for the pairing interaction with the hope to pick up
those states with the wave function being concentrated in the nuclear region
and perform the standard BCS approximation for the single particle states
generated by the RMF theory with deformation. We apply the RMF + BCS method to
the Zr isotopes and obtain a good description of the binding energies and the
nuclear radii of nuclei from the proton drip line to the neutron drip line.Comment: the version to be published in Progress of Theoretical Physic
Relativistic description of nuclear matrix elements in neutrinoless double- decay
Neutrinoless double- () decay is related to many
fundamental concepts in nuclear and particle physics beyond the standard model.
Currently there are many experiments searching for this weak process. An
accurate knowledge of the nuclear matrix element for the decay
is essential for determining the effective neutrino mass once this process is
eventually measured. We report the first full relativistic description of the
decay matrix element based on a state-of-the-art nuclear
structure model. We adopt the full relativistic transition operators which are
derived with the charge-changing nucleonic currents composed of the vector
coupling, axial-vector coupling, pseudoscalar coupling, and weak-magnetism
coupling terms. The wave functions for the initial and final nuclei are
determined by the multireference covariant density functional theory (MR-CDFT)
based on the point-coupling functional PC-PK1. The low-energy spectra and
electric quadrupole transitions in Nd and its daughter nucleus
Sm are well reproduced by the MR-CDFT calculations. The
decay matrix elements for both the
and decays of Nd are evaluated. The effects
of particle number projection, static and dynamic deformations, and the full
relativistic structure of the transition operators on the matrix elements are
studied in detail. The resulting decay matrix element for the
transition is , which gives the most optimistic
prediction for the next generation of experiments searching for the
decay in Nd.Comment: 17 pages, 9 figures; table adde
A feasibility study for the detection of upper atmospheric winds using a ground based laser Doppler velocimeter
A possible measurement program designed to obtain the information requisite to determining the feasibility of airborne and/or satellite-borne LDV (Laser Doppler Velocimeter) systems is discussed. Measurements made from the ground are favored over an airborne measurement as far as for the purpose of determining feasibility is concerned. The expected signal strengths for scattering at various altitude and elevation angles are examined; it appears that both molecular absorption and ambient turbulence degrade the signal at low elevation angles and effectively constrain the ground based measurement of elevation angles exceeding a critical value. The nature of the wind shear and turbulence to be expected are treated from a linear hydrodynamic model - a mountain lee wave model. The spatial and temporal correlation distances establish requirements on the range resolution, the maximum detectable range and the allowable integration time
Laser Doppler velocimeter system simulation for sensing aircraft wake vortices. Part 2: Processing and analysis of LDV data (for runs 1023 and 2023)
A data analysis program constructed to assess LDV system performance, to validate the simulation model, and to test various vortex location algorithms is presented. Real or simulated Doppler spectra versus range and elevation is used and the spatial distributions of various spectral moments or other spectral characteristics are calculated and displayed. Each of the real or simulated scans can be processed by one of three different procedures: simple frequency or wavenumber filtering, matched filtering, and deconvolution filtering. The final output is displayed as contour plots in an x-y coordinate system, as well as in the form of vortex tracks deduced from the maxima of the processed data. A detailed analysis of run number 1023 and run number 2023 is presented to demonstrate the data analysis procedure. Vortex tracks and system range resolutions are compared with theoretical predictions
Octet baryon masses in next-to-next-to-next-to-leading order covariant baryon chiral perturbation theory
We study the ground-state octet baryon masses and sigma terms using the
covariant baryon chiral perturbation theory (ChPT) with the
extended-on-mass-shell (EOMS) renormalization scheme up to
next-to-next-to-next-to-leading order (NLO). By adjusting the available 19
low-energy constants (LECs), a reasonable fit of the lattice quantum
chromodynamics (LQCD) results from the PACS-CS, LHPC, HSC, QCDSF-UKQCD and
NPLQCD collaborations is achieved. Finite-volume corrections to the lattice
data are calculated self-consistently. Our study shows that NLO BChPT
describes better the light quark mass evolution of the lattice data than the
NNLO BChPT does and the various lattice simulations seem to be consistent with
each other. We also predict the pion and strangeness sigma terms of the octet
baryons using the LECs determined in the fit of their masses. The predicted
pion- and strangeness-nucleon sigma terms are MeV and
MeV, respectively.Comment: 28 pages, 6 figures, minor revisions, typos corrected, version to
appear in JHE
- …