26,794 research outputs found
Spectroscopy of reflection-asymmetric nuclei with relativistic energy density functionals
Quadrupole and octupole deformation energy surfaces, low-energy excitation
spectra and transition rates in fourteen isotopic chains: Xe, Ba, Ce, Nd, Sm,
Gd, Rn, Ra, Th, U, Pu, Cm, Cf, and Fm, are systematically analyzed using a
theoretical framework based on a quadrupole-octupole collective Hamiltonian
(QOCH), with parameters determined by constrained reflection-asymmetric and
axially-symmetric relativistic mean-field calculations. The microscopic QOCH
model based on the PC-PK1 energy density functional and -interaction
pairing is shown to accurately describe the empirical trend of low-energy
quadrupole and octupole collective states, and predicted spectroscopic
properties are consistent with recent microscopic calculations based on both
relativistic and non-relativistic energy density functionals. Low-energy
negative-parity bands, average octupole deformations, and transition rates show
evidence for octupole collectivity in both mass regions, for which a
microscopic mechanism is discussed in terms of evolution of single-nucleon
orbitals with deformation.Comment: 36 pages, 21 figures, Accepted for Publication in Physical Review
Necessity of integral formalism
To describe the physical reality, there are two ways of constructing the
dynamical equation of field, differential formalism and integral formalism. The
importance of this fact is firstly emphasized by Yang in case of gauge field
[Phys. Rev. Lett. 33 (1974) 445], where the fact has given rise to a deeper
understanding for Aharonov-Bohm phase and magnetic monopole [Phys. Rev. D. 12
(1975) 3845]. In this paper we shall point out that such a fact also holds in
general wave function of matter, it may give rise to a deeper understanding for
Berry phase. Most importantly, we shall prove a point that, for general wave
function of matter, in the adiabatic limit, there is an intrinsic difference
between its integral formalism and differential formalism. It is neglect of
this difference that leads to an inconsistency of quantum adiabatic theorem
pointed out by Marzlin and Sanders [Phys. Rev. Lett. 93 (2004) 160408]. It has
been widely accepted that there is no physical difference of using differential
operator or integral operator to construct the dynamical equation of field.
Nevertheless, our study shows that the Schrodinger differential equation (i.e.,
differential formalism for wave function) shall lead to vanishing Berry phase
and that the Schrodinger integral equation (i.e., integral formalism for wave
function), in the adiabatic limit, can satisfactorily give the Berry phase.
Therefore, we reach a conclusion: There are two ways of describing physical
reality, differential formalism and integral formalism; but the integral
formalism is a unique way of complete description.Comment: 13Page; Schrodinger differential equation shall lead to vanishing
Berry phas
Topology of Knotted Optical Vortices
Optical vortices as topological objects exist ubiquitously in nature. In this
paper, by making use of the -mapping topological current theory, we
investigate the topology in the closed and knotted optical vortices. The
topological inner structure of the optical vortices are obtained, and the
linking of the knotted optical vortices is also given.Comment: 11 pages, no figures, accepted by Commun. Theor. Phys. (Beijing, P.
R. China
Langevin Dynamics of the vortex matter two-stage melting transition in Bi_2Sr_2CaCu_2O in the presence of straight and of tilted columnar defects
In this paper we use London Langevin molecular dynamics simulations to
investigate the vortex matter melting transition in the highly anisotropic
high-temperature superconductor material Bi_2Sr_2CaCu_2O in the
presence of low concentration of columnar defects (CDs). We reproduce with
further details our previous results obtained by using Multilevel Monte Carlo
simulations that showed that the melting of the nanocrystalline vortex matter
occurs in two stages: a first stage melting into nanoliquid vortex matter and a
second stage delocalization transition into a homogeneous liquid. Furthermore,
we report on new dynamical measurements in the presence of a current that
identifies clearly the irreversibility line and the second stage delocalization
transition. In addition to CDs aligned along the c-axis we also simulate the
case of tilted CDs which are aligned at an angle with respect to the applied
magnetic field. Results for CDs tilted by with respect to c-axis
show that the locations of the melting and delocalization transitions are not
affected by the tilt when the ratio of flux lines to CDs remains constant. On
the other hand we argue that some dynamical properties and in particular the
position of the irreversibility line should be affected.Comment: 13 pages, 11 figure
Topological Properties of Spatial Coherence Function
Topology of the spatial coherence function is considered in details. The
phase singularity (coherence vortices) structures of coherence function are
classified by Hopf index and Brouwer degree in topology. The coherence flux
quantization and the linking of the closed coherence vortices are also studied
from the topological properties of the spatial coherence function.Comment: 9 page
Cluster size dependence of high-order harmonic generation
We investigate high-order harmonic generation (HHG) from noble gas clusters
in a supersonic gas jet. To identify the contribution of harmonic generation
from clusters versus that from gas monomers, we measure the high-order harmonic
output over a broad range of the total atomic number density in the jet (from
3*10^16 cm^{-3} to 3x10^18 cm{-3}) at two different reservoir temperatures (303
K and 363 K). For the firrst time in the evaluation of the harmonic yield in
such measurements, the variation of the liquid mass fraction, g, versus
pressure and temperature is taken into consideration, which we determine,
reliably and consistently, to be below 20% within our range of experimental
parameters. By comparing the measured harmonic yield from a thin jet with the
calculated corresponding yield from monomers alone, we find an increased
emission of the harmonics when the average cluster size is less than 3000.
Using g, under the assumption that the emission from monomers and clusters add
up coherently, we calculate the ratio of the average single-atom response of an
atom within a cluster to that of a monomer and find an enhancement of around 10
for very small average cluster size (~200). We do not find any dependence of
the cut-off frequency on the composition of the cluster jet. This implies that
HHG in clusters is based on electrons that return to their parent ions and not
to neighbouring ions in the cluster. To fully employ the enhanced average
single-atom response found for small average cluster sizes (~200), the nozzle
producing the cluster jet must provide a large liquid mass fraction at these
small cluster sizes for increasing the harmonic yield. Moreover, cluster jets
may allow for quasi-phase matching, as the higher mass of clusters allows for a
higher density contrast in spatially structuring the nonlinear medium.Comment: 16 pages, 6 figure
The Effect of Pre-fermentative Freezing Treatment on the Sensory Quality of ‘Meili’ Rosé Wine
In this study, the effect of a pre-fermentative freezing treatment on quality attributes of ‘Meili’ rosé wine was assessed. Prior to fermentation, ‘Meili’ grapes (berries and must) were subjected to a freezing treatment considering factors of freezing temperatures, freezing time, and thawing method. Colour-related indices were measured by spectral methods. Wine aroma characteristics and sensory attributes were assessed by trained panellists. The results revealed that lower freezing temperature and longer freezing time had positive effects on wine quality attributes. The treatment of frozen berries might help extract colour-related compounds. Microwave thawing improved wine colour, but decreased taste quality. In the work, the MF-10°C/6 h treatment (microwave-thawed berries that had been frozen at -10°C for 6 h) contributed to the best colour characteristics, whereas the NP-20°C/4 h treatment (naturally-thawed must that had been frozen at -20°C for 4 h) contributed to the best taste attributes
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