11,678 research outputs found
Deduction of the quantum numbers of low-lying states of 6-nucleon systems based on symmetry
The inherent nodal structures of the wavefunctions of 6-nucleon systems have
been investigated. The existence of a group of six low-lying states dominated
by L=0 has been deduced. The spatial symmetries of these six states are found
to be mainly {4,2} and {2,2,2}.Comment: 8 pages, no figure
Ground Band and a Generalized GP-equation for Spinor Bose-Einstein Condensates
For the spinor Bose-Einstein condensates both the total spin and its
Z-component should be conserved. However, in existing theories, only
the conservation of has been taken into account. To remedy, this paper
is the first attempt to take the conservation of both and into
account. For this purpose, a total spin-state with the good quantum numbers
and is introduced in the trial wave function, thereby a generalized
Gross-Pitaevskii equation has been derived. With this new equation, the ground
bands of the Na and Rb condensates have been studied, where the
levels distinct in split. It was found that the level density is extremely
dense in the bottom of the ground band of Na, i.e., in the vicinity of
the ground state. On the contrary, for Rb, the levels are extremely
dense in the top of the ground band,Comment: 7 page, 5 figure
First excited band of a spinor Bose-Einstein condensate
The analytical expression of the fractional parentage coefficients for the
total spin-states of a spinor N-boson system has been derived. Thereby an
S-conserved theory for the spinor Bose-Einstein condensation has been proposed.
A set of equations has been established to describe the first excited band of
the condensates. Numerical solution for Na has been given as an example.Comment: 6 pages, 3 figure
Mapping the Dirac point in gated bilayer graphene
We have performed low temperature scanning tunneling spectroscopy
measurements on exfoliated bilayer graphene on SiO2. By varying the back gate
voltage we observed a linear shift of the Dirac point and an opening of a band
gap due to the perpendicular electric field. In addition to observing a shift
in the Dirac point, we also measured its spatial dependence using spatially
resolved scanning tunneling spectroscopy. The spatial variation of the Dirac
point was not correlated with topographic features and therefore we attribute
its shift to random charged impurities.Comment: 3 pages, 3 figure
Spatially resolved spectroscopy of monolayer graphene on SiO2
We have carried out scanning tunneling spectroscopy measurements on
exfoliated monolayer graphene on SiO to probe the correlation between its
electronic and structural properties. Maps of the local density of states are
characterized by electron and hole puddles that arise due to long range
intravalley scattering from intrinsic ripples in graphene and random charged
impurities. At low energy, we observe short range intervalley scattering which
we attribute to lattice defects. Our results demonstrate that the electronic
properties of graphene are influenced by intrinsic ripples, defects and the
underlying SiO substrate.Comment: 6 pages, 7 figures, extended versio
Low-lying S-wave and P-wave Dibaryons in a Nodal Structure Analysis
The dibaryon states as six-quark clusters of exotic QCD states are
investigated in this paper. With the inherent nodal surface structure analysis,
the wave functions of the six-quark clusters (in another word, the dibaryons)
are classified. The contribution of the hidden color channels are discussed.
The quantum numbers of the low-lying dibaryon states are obtained. The States
, ,
, and the
hidden color channel states with the same quantum numbers are proposed to be
the candidates of dibaryons, which may be observed in experiments.Comment: 29 pages, 2 figure
Repeating head-on collisions in an optical trap and the evaluation of spin-dependent interactions among neutral particles
A dynamic process of repeating collisions of a pair of trapped neutral
particles with weak spin-dependent interaction is designed and studied. Related
theoretical derivation and numerical calculation have been performed to study
the inherent coordinate-spin and momentum-spin correlation. Due to the
repeating collisions the effect of the weak interaction can be accumulated and
enlarged, and therefore can be eventually detected. Numerical results suggest
that the Cr-Cr interaction, which has not yet been completely clear, could be
thereby determined. The design can be in general used to determine various
interactions among neutral atoms and molecules, in particular for the
determination of very weak forces.Comment: 15 pages, 7 figure
Study the Heavy Molecular States in Quark Model with Meson Exchange Interaction
Some charmonium-like resonances such as X(3872) can be interpreted as
possible molecular states. Within the quark model, we study
the structure of such molecular states and the similar
molecular states by taking into account of the light meson exchange (,
, , and ) between two light quarks from different
mesons
Mean free paths and in-medium scattering cross sections of energetic nucleons in neutron-rich nucleonic matter within the relativistic impulse approximation
The mean free paths and in-medium scattering cross sections of energetic
nucleons in neutron-rich nucleonic matter are investigated using the nucleon
optical potential obtained within the relativistic impulse approximation with
the empirical nucleon-nucleon scattering amplitudes and the nuclear densities
obtained in the relativistic mean field model. It is found that the
isospin-splitting of nucleon mean free paths, sensitive to the imaginary part
of the symmetry potential, changes its sign at certain high kinetic energy. The
in-medium nucleon-nucleon cross sections are analytically and numerically
demonstrated to be essentially independent of the isospin asymmetry of the
medium and increase linearly with density in the high energy region where the
relativistic impulse approximation is applicable.Comment: 13 pages, 6 figure
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