41,566 research outputs found
Microscopic models for Kitaev's sixteenfold way of anyon theories
In two dimensions, the topological order described by gauge
theory coupled to free or weakly interacting fermions with a nonzero spectral
Chern number is classified by as predicted by
Kitaev [Ann. Phys. 321, 2 (2006)]. Here we provide a systematic and complete
construction of microscopic models realizing this so-called sixteenfold way of
anyon theories. These models are defined by matrices satisfying the
Clifford algebra, enjoy a global symmetry, and live on
either square or honeycomb lattices depending on the parity of . We show
that all these models are exactly solvable by using a Majorana representation
and characterize the topological order by calculating the topological spin of
an anyonic quasiparticle and the ground-state degeneracy. The possible
relevance of the and models to materials with
Kugel-Khomskii-type spin-orbital interactions is discussed.Comment: 6+9 pages, 2+1 figures, published versio
Hadronization Approach for a Quark-Gluon Plasma Formed in Relativistic Heavy Ion Collisions
A transport model is developed to describe hadron emission from a strongly
coupled quark-gluon plasma formed in relativistic heavy ion collisions. The
quark-gluon plasma is controlled by ideal hydrodynamics, and the hadron motion
is characterized by a transport equation with loss and gain terms. The two sets
of equations are coupled to each other, and the hadronization hypersurface is
determined by both the hydrodynamic evolution and the hadron emission. The
model is applied to calculate the transverse momentum distributions of mesons
and baryons, and most of the results agree well with the experimental data at
RHIC.Comment: 16 pages, 24 figures. Version accepted by PR
Reconsideration of Second Harmonic Generation from neat Air/Water Interface: Broken of Kleinman Symmetry from Dipolar Contribution
It has been generally accepted that there are significant quadrupolar and
bulk contributions to the second harmonic generation (SHG) reflected from the
neat air/water interface, as well as common liquid interfaces. Because there
has been no general methodology to determine the quadrupolar and bulk
contributions to the SHG signal from a liquid interface, this conclusion was
reached based on the following two experimental phenomena. Namely, the broken
of the macroscopic Kleinman symmetry, and the significant temperature
dependence of the SHG signal from the neat air/water interface. However,
because sum frequency generation vibrational spectroscopy (SFG-VS) measurement
of the neat air/water interface observed no apparent temperature dependence,
the temperature dependence in the SHG measurement has been reexamined and
proven to be an experimental artifact. Here we present a complete microscopic
analysis of the susceptibility tensors of the air/water interface, and show
that dipolar contribution alone can be used to address the issue of broken of
the macroscopic Kleinman symmetry at the neat air/water interface. Using this
analysis, the orientation of the water molecules at the interface can be
obtained, and it is consistent with the measurement from SFG-VS. Therefore, the
key rationales to conclude significantly quadrupolar and bulk contributions to
the SHG signal of the neat air/water interface can no longer be considered as
valid as before. This new understanding of the air/water interface can shed
light on our understanding of the nonlinear optical responses from other
molecular interfaces as well
Dressed Polyakov loop and flavor dependent phase transitions
The chiral condensate and dressed Polyakov loop at finite temperature and
density have been investigated in the framework of Nf = 2+1 Nambu-Jona-Lasinio
(NJL) model with two degenerate u, d quarks and one strange quark. In the case
of explicit chiral symmetry breaking with physical quark masses, it is found
that the phase transitions for light u, d quarks and s quark are sequentially
happened, and the separation between the transition lines for different flavors
becomes wider and wider with the increase of baryon density. For each flavor,
the pseudo-critical temperatures for chiral condensate and dressed Polyakov
loop differ in a narrow transition range in the lower baryon density region,
and the two transitions coincide in the higher baryon density region.Comment: 9 pages, 9 figures; Version accepted in Phys. Rev.
Microbial ecology of Thiobacillus ferrooxidans
FINAL TECHNICAL REPORT
TO
U.S. DEPARTMENT OF THE INTERIOR
Geological Survey
Washington. D.C.The contents of this report were developed in part under a grant from
the Department of the Interior, U.S. Geological Survey. Grant number 14-08-0001-61313
Earth matter density uncertainty in atmospheric neutrino oscillations
That muon neutrinos oscillating into the mixture of tau neutrinos
and sterile neutrinos has been studied to explain the
atmospheric disappearance. In this scenario, the effect of Earth
matter is a key to determine the fraction of . Considering that the
Earth matter density has uncertainty and this uncertainty has significant
effects in some neutrino oscillation cases, such as the CP violation in very
long baseline neutrino oscillations and the day-night asymmetry for solar
neutrinos, we study the effects caused by this uncertainty in the above
atmospheric oscillation scenario. We find that this uncertainty
seems to have no significant effects and that the previous fitting results need
not to be modified fortunately.Comment: 7 pages, 1 figure, to appear in Phys. Rev.
Thermal quench effects on ferroelectric domain walls
Using piezoresponse force microscopy on epitaxial ferroelectric thin films,
we have measured the evolution of domain wall roughening as a result of
heat-quench cycles up to 735C, with the effective roughness exponent \zeta\
changing from 0.25 to 0.5. We discuss two possible mechanisms for the observed
\zeta\ increase: a quench from a thermal 1-dimensional configuration, and from
a locally-equilibrated pinned configuration with a crossover from a 2- to
1-dimensional regime. We find that the post-quench spatial structure of the
metastable states, qualitatively consistent with the existence of a growing
dynamical length scale whose ultra slow evolution is primarily controlled by
the defect configuration and heating process parameters, makes the second
scenario more plausible. This interpretation suggests that pinning is relevant
in a wide range of temperatures, and in particular, that purely thermal domain
wall configurations might not be observable in this glassy system. We also
demonstrate the crucial effects of oxygen vacancies in stabilizing domain
structures.Comment: 17 pages (preprint), 4 figure
- …