4,870 research outputs found
Phytohaemagglutinin on maternal and umbilical leukocytes
Almost all the umbilical lymphocytes showed more extensive blast cell formation
than that of their mother's lymphocytes with PHA. Pathological conditions of mother in pregnancy and labor such as anemia, gestational toxicosis,
difficult labor and asphyxia of babies, inhibited the normal response of both maternal and umbilical lymphocytes to PHA.</p
Mott Transitions of Three-Component Fermionic Atoms with Repulsive Interaction in Optical Lattices
We investigate the Mott transitions of three-component (colors) repulsive
fermionic atoms in optical lattices using the dynamical mean field theory. We
find that for SU(3) symmetry breaking interactions the Mott transition occurs
at incommensurate half filling. As a result, a characteristic Mott insulating
state appears, where paired atoms with two different colors and atoms with the
third color are localized at different sites. We also find another Mott state
where atoms with two different colors are localized at different sites and
atoms with the third color remain itinerant. We demonstrate that these exotic
Mott phases can be detected by experimental double occupancy observations.Comment: 5 pages, 4 figure
Supersolid state in fermionic optical lattice systems
We study ultracold fermionic atoms trapped in an optical lattice with
harmonic confinement by combining the real-space dynamical mean-field theory
with a two-site impurity solver. By calculating the local particle density and
the pair potential in the systems with different clusters, we discuss the
stability of a supersolid state, where an s-wave superfluid coexists with a
density-wave state of checkerboard pattern. It is clarified that a confining
potential plays an essential role in stabilizing the supersolid state. The
phase diagrams are obtained for several effective particle densities.Comment: 7 pages, 5 figures, Phys. Rev. A in pres
Finite-temperature Mott transitions in multi-orbital Hubbard model
We investigate the Mott transitions in the multi-orbital Hubbard model at
half-filling by means of the self-energy functional approach. The phase
diagrams are obtained at finite temperatures for the Hubbard model with up to
four-fold degenerate bands. We discuss how the first-order Mott transition
points and as well as the critical temperature depend
on the orbital degeneracy. It is elucidated that enhanced orbital fluctuations
play a key role to control the Mott transitions in the multi-orbital Hubbard
model.Comment: 8 pages, 7 figure
Magnetism and domain formation in SU(3)-symmetric multi-species Fermi mixtures
We study the phase diagram of an SU(3)-symmetric mixture of three-component
ultracold fermions with attractive interactions in an optical lattice,
including the additional effect on the mixture of an effective three-body
constraint induced by three-body losses. We address the properties of the
system in by using dynamical mean-field theory and variational Monte
Carlo techniques. The phase diagram of the model shows a strong interplay
between magnetism and superfluidity. In the absence of the three-body
constraint (no losses), the system undergoes a phase transition from a color
superfluid phase to a trionic phase, which shows additional particle density
modulations at half-filling. Away from the particle-hole symmetric point the
color superfluid phase is always spontaneously magnetized, leading to the
formation of different color superfluid domains in systems where the total
number of particles of each species is conserved. This can be seen as the SU(3)
symmetric realization of a more general tendency to phase-separation in
three-component Fermi mixtures. The three-body constraint strongly disfavors
the trionic phase, stabilizing a (fully magnetized) color superfluid also at
strong coupling. With increasing temperature we observe a transition to a
non-magnetized SU(3) Fermi liquid phase.Comment: 36 pages, 17 figures; Corrected typo
Metal-insulator transition in the two-orbital Hubbard model at fractional band fillings: Self-energy functional approach
We investigate the infinite-dimensional two-orbital Hubbard model at
arbitrary band fillings. By means of the self-energy functional approach, we
discuss the stability of the metallic state in the systems with same and
different bandwidths. It is found that the Mott insulating phases are realized
at commensurate band fillings. Furthermore, it is clarified that the orbital
selective Mott phase with one orbital localized and the other itinerant is
stabilized even at fractional band fillings in the system with different
bandwidths.Comment: 7 pages, 10 figure
Electronic states around a vortex core in high-Tc superconductors based on the t-J model
Electronic states around vortex cores in high-Tc superconductors are studied
using the two-dimensional t-J model in order to treat the d-wave
superconductivity with short coherence length and the antiferromagnetic (AF)
instability within the same framework. We focus on the disappearance of the
large zero-energy peak in the local density of states observed in high-Tc
superconductors. When the system is near the optimum doping, we find that the
local AF correlation develops inside the vortex cores. However, the detailed
doping dependence calculations confirm that the experimentally observed
reduction of the zero-energy peak is more reasonably attributed to the
smallness of the core size rather than to the AF correlation developed inside
the core. The correlation between the spatial dependence of the core states and
the core radius is discussed.Comment: 4 pages, 4 figure
Heavy Quasi-Particle in the Two-Orbital Hubbard Model
The two-orbital Hubbard model with the Hund coupling is investigated in a
metallic phase close to the Mott insulator. We calculate the one-particle
spectral function and the optical conductivity within dynamical mean field
theory, for which the effective impurity problem is solved by using the
non-crossing approximation. For a metallic system close to quarter filling, a
heavy quasi-particle band is formed by the Hubbard interaction, the effective
mass of which is not so sensitive to the orbital splitting and the Hund
coupling. In contrast, a heavy quasi-particle band near half filling disappears
in the presence of the orbital splitting, but is induced again by the
introduction of the Hund coupling, resulting in a different type of heavy
quasi-particles.Comment: 6page, 7eps figures, to appear in J. Phys. Soc. Jp
A study of the etapipi channel produced in central pp interactions at 450 GeV/c
The reaction pp -> pf (eta pi pi) ps has been studied at 450 GeV/c. There is
clear evidence for an a2(1320)pi decay mode of the eta2(1645) and eta2(1870).
In addition, there is evidence for an a0(980)pi$ decay mode of both resonances
and an f2(1270)eta decay mode of the eta2(1870). No evidence is found for a JPC
= 2++ a2(1320)pi wave.Comment: 15 pages, Latex, 4 Figures Branching ratio a2pi /f2 eta correcte
Possible Ordered States in the 2D Extended Hubbard Model
Possible ordered states in the 2D extended Hubbard model with on-site (U>0)
and nearest-neighbor (V) interaction are examined near half filling, with
emphasis on the effect of finite V. First, the phase diagram at absolute zero
is determined in the mean field approximation. For , a state where
d_{x^{2}-y^{2}}-wave superconductivity (dSC), commensurate spin-density-wave
(SDW) and -triplet pair coexist is seen to be stabilized. Here, the
importance of -triplet pair on the coexistence of dSC and SDW is
indicated. This coexistent state is hampered by the phase separation (PS),
which is generally expected to occur in the presence of finite-range attractive
interaction, but survives. For V>0, a state where commensurate
charge-density-wave (CDW), SDW and ferromagnetism (FM) coexist is seen to be
stabilized. Here, the importance of FM on the coexistence of CDW and SDW is
indicated. Next, in order to examine the effects of fluctuation on each mean
field ordered state, the renormalization group method for the special case that
the Fermi level lies just on the saddle points, (,0) and (0,), is
applied. The crucial difference from the mean field result is that
superconductivity can arise even for U>0 and , where the
superconducting gap symmetry is d_{x^{2}-y^{2}}-wave for U>4V and s-wave for
U<4V. Finally, the possibilities that the mean field coexistent states survive
in the presence of fluctuation are discussed.Comment: 12 pages, 19 figures included, revised versio
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