12,511 research outputs found
Thermodynamic properties and phase diagrams of spin-1 quantum Ising systems with three-spin interactions
The spin-1 quantum Ising systems with three-spin interactions on
two-dimensional triangular lattices are studied by mean-field method. The
thermal variations of order parameters and phase diagrams are investigated in
detail. The stable, metastable and unstable branches of the order parameters
are obtained. According to the stable conditions at critical point, we find
that the systems exhibit tricritical points. With crystal field and biquadratic
interactions, the system has rich phase diagrams with single reentrant or
double reentrant phase transitions for appropriate ranges of the both
parameters.Comment: 10 pages, 5 figure
Use of low-energy hydrogen ion implants in high-efficiency crystalline-silicon solar cells
The use of low-energy hydrogen implants in the fabrication of high-efficiency crystalline silicon solar cells was investigated. Low-energy hydrogen implants result in hydrogen-caused effects in all three regions of a solar cell: emitter, space charge region, and base. In web, Czochralski (Cz), and floating zone (Fz) material, low-energy hydrogen implants reduced surface recombination velocity. In all three, the implants passivated the space charge region recombination centers. It was established that hydrogen implants can alter the diffusion properties of ion-implanted boron in silicon, but not ion-implated arsenic
Non-Abelian Proca model based on the improved BFT formalism
We present the newly improved Batalin-Fradkin-Tyutin (BFT) Hamiltonian
formalism and the generalization to the Lagrangian formulation, which provide
the much more simple and transparent insight to the usual BFT method, with
application to the non-Abelian Proca model which has been an difficult problem
in the usual BFT method. The infinite terms of the effectively first class
constraints can be made to be the regular power series forms by ingenious
choice of and -matrices. In this new
method, the first class Hamiltonian, which also needs infinite correction terms
is obtained simply by replacing the original variables in the original
Hamiltonian with the BFT physical variables. Remarkably all the infinite
correction terms can be expressed in the compact exponential form. We also show
that in our model the Poisson brackets of the BFT physical variables in the
extended phase space are the same structure as the Dirac brackets of the
original phase space variables. With the help of both our newly developed
Lagrangian formulation and Hamilton's equations of motion, we obtain the
desired classical Lagrangian corresponding to the first class Hamiltonian which
can be reduced to the generalized St\"uckelberg Lagrangian which is non-trivial
conjecture in our infinitely many terms involved in Hamiltonian and Lagrangian.Comment: Notable improvements in Sec. I
Low Scale Non-universal, Non-anomalous U(1)'_F in a Minimal Supersymmetric Standard Model
We propose a non-universal U(1)'_F symmetry combined with the Minimal
Supersymmetric Standard Model. All anomaly cancellation conditions are
satisfied without exotic fields other than three right-handed neutrinos.
Because our model allows all three generations of chiral superfields to have
different U(1)'_F charges, upon the breaking of the U(1)'_F symmetry at a low
scale, realistic masses and mixing angles in both the quark and lepton sectors
are obtained. In our model, neutrinos are predicted to be Dirac fermions and
their mass ordering is of the inverted hierarchy type. The U(1)'_F charges of
the chiral super-fields also naturally suppress the mu term and automatically
forbid baryon number and lepton number violating operators. While all
flavor-changing neutral current constraints in the down quark and charged
lepton sectors can be satisfied, we find that constraint from D0-D0bar turns
out to be much more stringent than the constraints from the precision
electroweak data.Comment: 21 pages, 2 figures; v2: discussion on sparticle mass spectrum
included, 27 pages, 2 figure
Canonical Charmonium Interpretation for Y(4360) and Y(4660)
In this work, we consider the canonical charmonium assignments for Y(4360)
and Y(4660). Y(4660) is good candidate of state, the
possibility of Y(4360) as a state is studied, and the
charmonium hybrid interpretation of Y(4360) can not be excluded completely. We
evaluate the leptonic widths, E1 transitions, M1 transitions and
the open flavor strong decays of Y(4360) and Y(4660). Experimental tests for
the charmonium assignments are suggested.Comment: 32 pages, 4 figure
BRST Quantization of the Proca Model based on the BFT and the BFV Formalism
The BRST quantization of the Abelian Proca model is performed using the
Batalin-Fradkin-Tyutin and the Batalin-Fradkin-Vilkovisky formalism. First, the
BFT Hamiltonian method is applied in order to systematically convert a second
class constraint system of the model into an effectively first class one by
introducing new fields. In finding the involutive Hamiltonian we adopt a new
approach which is more simpler than the usual one. We also show that in our
model the Dirac brackets of the phase space variables in the original second
class constraint system are exactly the same as the Poisson brackets of the
corresponding modified fields in the extended phase space due to the linear
character of the constraints comparing the Dirac or Faddeev-Jackiw formalisms.
Then, according to the BFV formalism we obtain that the desired resulting
Lagrangian preserving BRST symmetry in the standard local gauge fixing
procedure naturally includes the St\"uckelberg scalar related to the explicit
gauge symmetry breaking effect due to the presence of the mass term. We also
analyze the nonstandard nonlocal gauge fixing procedure.Comment: 29 pages, plain Latex, To be published in Int. J. Mod. Phys.
Proton-Antiproton Annihilation in Baryonium
A possible interpretation of the near-threshold enhancement in the
-mass spectrum in is the of existence
of a narrow baryonium resonance X(1860). Mesonic decays of the
-bound state X(1860) due to the nucleon-antinucleon annihilation
are investigated in this paper. Mesonic coherent states with fixed -parity
and -parity have been constructed . The Amado-Cannata-Dedoder-Locher-Shao
formulation(Phys Rev Lett. {\bf 72}, 970 (1994)) is extended to the decays of
the X(1860). By this method, the branch-fraction ratios of , and are calculated. It is shown
that if the X(1860) is a bound state of , the decay channel ( is favored over . In this way, we develop
criteria for distinguishing the baryonium interpretation for the near-threshold
enhancement effects in -mass spectrum in from other possibilities. Experimental checks are expected. An intuitive
picture for our results is discussed.Comment: 19 pages, 3 figure
Suppression of backward scattering of Dirac fermions in iron pnictides Ba(FeRuAs)
We report electronic transport of Dirac cones when Fe is replaced by Ru,
which has an isoelectronic electron configuration to Fe, using single crystals
of Ba(FeRuAs). The electronic transport of parabolic bands is
shown to be suppressed by scattering due to the crystal lattice distortion and
the impurity effect of Ru, while that of the Dirac cone is not significantly
reduced due to the intrinsic character of Dirac cones. It is clearly shown from
magnetoresistance and Hall coefficient measurements that the inverse of average
mobility, proportional to cyclotron effective mass, develops as the square root
of the carrier number (n) of the Dirac cones. This is the unique character of
the Dirac cone linear dispersion relationship. Scattering of Ru on the Dirac
cones is discussed in terms of the estimated mean free path using experimental
parameters.Comment: 6 pages, 3 figures, To be published in Phys. Rev.
The dynamics of gender in the intergenerational transmission of homeownership:A case study of young couples in Shanghai
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