1,071 research outputs found
Nuclear shell-model calculations for 6Li and 14N with different NN potentials
Two ``phase-shift equivalent'' local NN potentials with different
parametrizations, Reid93 and NijmII, which were found to give nearly identical
results for the triton by Friar et al, are shown to yield remarkably similar
results for 6Li and 14N in a (0+2)hw no-core space shell-model calculation. The
results are compared with those for the widely used Hamada-Johnson hard-core
and the original Reid soft-core potentials, which have larger deuteron D-state
percentages. The strong correlation between the tensor strength and the nuclear
binding energy is confirmed. However, many nuclear-structure properties seem to
be rather insensitive to the details of the NN potential and, therefore, cannot
be used to test various NN potentials. (Submitted to Phys. Rev. C on Nov. 9,
1993 as a Brief Report.)Comment: 12 text pages and 1 figure (Figure available upon request),
University of Arizona Physics Preprint (Number not yet assigned
Scale invariance in coarsening of binary and ternary fluids
Phase separation in binary and ternary fluids is studied using a two
dimensional Lattice Gas Automata. The lengths, given by the the first zero
crossing point of the correlation function and the total interface length is
shown to exhibit power law dependence on time. In binary mixtures, our data
clearly indicate the existence of a regime having more than one length scale
where the coarsening process proceeds through the rupture and reassociation of
domains. In ternary fluids; in the case of symmetric mixtures there exists a
regime with a single length scale having dynamic exponent 1/2, while in
asymmetric mixtures our data establish the break down of scale invariance.Comment: 20 pages, 13 figure
Small damping approach in Fermi-liquid theory
The validity of small damping approximation (SDA) for the quasi-classical
description of the averaged properties of nuclei at high temperatures is
studied within the framework of collisional kinetic theory. The isoscalar
collective quadrupole vibrations in hot nuclei are considered. We show that the
extension of the SDA, by accounting for the damping of the distribution
function in the collision integral reduces the rate of variation
with temperature of the Fermi surface distortion effects. The damping of the
in the collision integral increases significantly the collisional
width of the giant quadrupole resonance (GQR) for small enough values of the
relaxation time. The temperature dependence of the eigenenergy of the GQR
becomes much more weaker than in the corresponding SDA case.Comment: 11 pages, 3 figure
Cosmological Implications of Neutrinos
The lectures describe several cosmological effects produced by neutrinos.
Upper and lower cosmological limits on neutrino mass are derived. The role that
neutrinos may play in formation of large scale structure of the universe is
described and neutrino mass limits are presented. Effects of neutrinos on
cosmological background radiation and on big bang nucleosynthesis are
discussed. Limits on the number of neutrino flavors and mass/mixing are given.Comment: 41 page, 7 figures; lectures presented at ITEP Winter School,
February, 2002; to be published in the Proceeding
Scoping review : intergenerational resource transfer and possible enabling factors
We explore the intergenerational pattern of resource transfer and possible associated factors. A scoping review was conducted of quantitative, peer-reviewed, English-language studies related to intergenerational transfer or interaction. We searched AgeLine, PsycINFO, Social Work Abstracts, and Sociological Abstracts for articles published between Jane 2008 and December 2018. Seventy-five studies from 25 countries met the inclusion criteria. The scoping review categorised resource transfers into three types: financial, instrumental, and emotional support. Using an intergenerational solidarity framework, factors associated with intergenerational transfer were placed in four categories: (1) demographic factors (e.g., age, gender, marital status, education, and ethno-cultural background); (2) needs and opportunities factors, including health, financial resources, and employment status; (3) family structures, namely, family composition, family relationship, and earlier family events; and (4) cultural-contextual structures, including state policies and social norms. Those factors were connected to the direction of resource transfer between generations. Downward transfers from senior to junior generations occur more frequently than upward transfers in many developed countries. Women dominate instrumental transfers, perhaps influenced by traditional gender roles. Overall, the pattern of resource transfer between generations is shown, and the impact of social norms and social policy on intergenerational transfers is highlighted. Policymakers should recognise the complicated interplay of each factor with different cultural contexts. The findings could inform policies that strengthen intergenerational solidarity and support.</jats:p
Interacting one dimensional electron gas with open boundaries
We discuss the properties of interacting electrons on a finite chain with
open boundary conditions. We extend the Haldane Luttinger liquid description to
these systems and study how the presence of the boundaries modifies various
correlation functions. In view of possible experimental applications to quantum
wires, we analyse how tunneling measurements can reveal the underlying
Luttinger liquid properties. The two terminal conductance is calculated. We
also point out possible applications to quasi one dimensional materials and
study the effects of magnetic impurities.Comment: 38 pages, ReVTeX, 7 figures (available upon request
Spin- and charge-density oscillations in spin chains and quantum wires
We analyze the spin- and charge-density oscillations near impurities in spin
chains and quantum wires. These so-called Friedel oscillations give detailed
information about the impurity and also about the interactions in the system.
The temperature dependence of these oscillations explicitly shows the
renormalization of backscattering and conductivity, which we analyze for a
number of different impurity models. We are also able to analyze screening
effects in one dimension. The relation to the Kondo effect and experimental
consequences are discussed.Comment: Final published version. 15 pages in revtex format including 22
epsf-embedded figures. The latest version in PDF format is available from
http://fy.chalmers.se/~eggert/papers/density-osc.pd
Primordial Nucleosynthesis Constraints on Z' Properties
In models involving new TeV-scale Z' gauge bosons, the new U(1)' symmetry
often prevents the generation of Majorana masses needed for a conventional
neutrino seesaw, leading to three superweakly interacting ``right-handed''
neutrinos nu_R, the Dirac partners of the ordinary neutrinos. These can be
produced prior to big bang nucleosynthesis by the Z' interactions, leading to a
faster expansion rate and too much ^4He. We quantify the constraints on the Z'
properties from nucleosynthesis for Z' couplings motivated by a class of E_6
models parametrized by an angle theta_E6. The rate for the annihilation of
three approximately massless right-handed neutrinos into other particle pairs
through the Z' channel is calculated. The decoupling temperature, which is
higher than that of ordinary left-handed neutrinos due to the large Z' mass, is
evaluated, and the equivalent number of new doublet neutrinos Delta N_nu is
obtained numerically as a function of the Z' mass and couplings for a variety
of assumptions concerning the Z-Z' mixing angle and the quark-hadron transition
temperature T_c. Except near the values of theta_E6 for which the Z' decouples
from the right-handed neutrinos, the Z' mass and mixing constraints from
nucleosynthesis are much more stringent than the existing laboratory limits
from searches for direct production or from precision electroweak data, and are
comparable to the ranges that may ultimately be probed at proposed colliders.
For the case T_c = 150 MeV with the theoretically favored range of Z-Z'
mixings, Delta N_nu 4.3 TeV for any value of theta_E6. Larger
mixing or larger T_c often lead to unacceptably large Delta N_nu except near
the nu_R decoupling limit.Comment: 22 pages, 5 figures; two additional references adde
Large lepton asymmetry from Q-balls
We propose a scenario which can explain large lepton asymmetry and small
baryon asymmetry simultaneously. Large lepton asymmetry is generated through
Affleck-Dine (AD) mechanism and almost all the produced lepton numbers are
absorbed into Q-balls (L-balls). If the lifetime of the L-balls is longer than
the onset of electroweak phase transition but shorter than the epoch of big
bang nucleosynthesis (BBN), the large lepton asymmetry in the L-balls is
protected from sphaleron effects. On the other hand, small (negative) lepton
numbers are evaporated from the L-balls due to thermal effects, which are
converted into the observed small baryon asymmetry by virtue of sphaleron
effects. Large and positive lepton asymmetry of electron type is often
requested from BBN. In our scenario, choosing an appropriate flat direction in
the minimal supersymmetric standard model (MSSM), we can produce positive
lepton asymmetry of electron type but totally negative lepton asymmetry.Comment: 10 pages, 3 figures, ReVTeX
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