29,699 research outputs found
Modification of nucleon properties in nuclear matter and finite nuclei
We present a model for the description of nuclear matter and finite nuclei,
and at the same time, for the study of medium modifications of nucleon
properties. The nucleons are described as nontopological solitons which
interact through the self-consistent exchange of scalar and vector mesons. The
model explicitly incorporates quark degrees of freedom into nuclear many-body
systems and provides satisfactory results on the nuclear properties. The
present model predicts a significant increase of the nucleon radius at normal
nuclear matter density. It is very interesting to see the nucleon properties
change from the nuclear surface to the nuclear interior.Comment: 22 pages, 10 figure
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White matter hyperintensities and within-person variability in community-dwelling adults aged 60–64 years
Estimates of white matter hyperintensities (WMH) derived from T2-weighted MRI were investigated in relation to cognitive performance in 469 healthy community-dwelling adults aged 60–64 years. Frontal lobe WMH but not WMH from other brain regions (temporal, parietal, and occipital lobes, anterior and posterior horn, periventricular body) were associated with elevated within-person reaction time (RT) variability (trial to trial fluctuations in RT performance) but not performance on several other cognitive tasks including psychomotor speed, memory, and global cognition. The findings are consistent with the view that elevated within-person variability is related to neurobiological disturbance, and that attentional mechanisms supported by the frontal cortex play a key role in this type of variability
Thermalized Displaced Squeezed Thermal States
In the coordinate representation of thermofield dynamics, we investigate the
thermalized displaced squeezed thermal state which involves two temperatures
successively. We give the wavefunction and the matrix element of the density
operator at any time, and accordingly calculate some quantities related to the
position, momentum and particle number operator, special cases of which are
consistent with the results in the literature. The two temperatures have
diffenent correlations with the squeeze and coherence components. Moreover,
different from the properties of the position and momentum, the average value
and variance of the particle number operator as well as the second-order
correlation function are time-independent.Comment: 7 pages, no figures, Revtex fil
Hole Doping Dependence of the Coherence Length in Thin Films
By measuring the field and temperature dependence of magnetization on
systematically doped thin films, the critical current
density and the collective pinning energy are determined in
single vortex creep regime. Together with the published data of superfluid
density, condensation energy and anisotropy, for the first time we derive the
doping dependence of the coherence length or vortex core size in wide doping
regime directly from the low temperature data. It is found that the coherence
length drops in the underdoped region and increases in the overdoped side with
the increase of hole concentration. The result in underdoped region clearly
deviates from what expected by the pre-formed pairing model if one simply
associates the pseudogap with the upper-critical field.Comment: 4 pages, 4 figure
Continuous topological phase transitions between clean quantum Hall states
Continuous transitions between states with the {\em same} symmetry but
different topological orders are studied. Clean quantum Hall (QH) liquids with
neutral quasiparticles are shown to have such transitions. For clean bilayer
(nnm) states, a continous transition to other QH states (including non-Abelian
states) can be driven by increasing interlayer repulsion/tunneling. The
effective theories describing the critical points at some transitions are
derived.Comment: 4 pages, RevTeX, 2 eps figure
Renormalization Group Study of Magnetic Catalysis in the 3d Gross-Neveu Model
Magnetic catalysis describes the enhancement of symmetry breaking quantum
fluctuations in chirally symmetric quantum field theories by the coupling of
fermionic degrees of freedom to a magnetic background configuration. We use the
functional renormalization group to investigate this phenomenon for interacting
Dirac fermions propagating in (2+1)-dimensional spacetime, described by the
Gross-Neveu model. We identify pointlike operators up to quartic fermionic
terms that can be generated in the renormalization group flow by the presence
of an external magnetic field. We employ the beta function for the fermionic
coupling to quantitatively analyze the field dependence of the induced spectral
gap. Within our pointlike truncation, the renormalization group flow provides a
simple picture for magnetic catalysis.Comment: 14 pages, 6 figures, typos correcte
A novel mechanism of charge density wave in a transition metal dichalcogenide
Charge density wave, or CDW, is usually associated with Fermi surfaces
nesting. We here report a new CDW mechanism discovered in a 2H-structured
transition metal dichalcogenide, where the two essential ingredients of CDW are
realized in very anomalous ways due to the strong-coupling nature of the
electronic structure. Namely, the CDW gap is only partially open, and charge
density wavevector match is fulfilled through participation of states of the
large Fermi patch, while the straight FS sections have secondary or negligible
contributions.Comment: 5 pages and 4 figure
Modified Bennett-Brassard 1984 Quantum Key Distribution With Two-way Classical Communications
The quantum key distribution protocol without public announcement of bases is
equipped with a two-way classical communication symmetric entanglement
purification protocol. This modified key distribution protocol is
unconditionally secure and has a higher tolerable error rate of 20%, which is
higher than previous scheme without public announcement of bases.Comment: 5 pages. To appear in Physical Review
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