4,952 research outputs found
N=2 Supersymmetric Model with Dirac-Kahler Fermions from Generalized Gauge Theory in Two Dimensions
We investigate the generalized gauge theory which has been proposed
previously and show that in two dimensions the instanton gauge fixing of the
generalized topological Yang-Mills action leads to a twisted N=2 supersymmetric
action. We have found that the R-symmetry of N=2 supersymmetry can be
identified with the flavour symmetry of Dirac-Kahler fermion formulation. Thus
the procedure of twist allows topological ghost fields to be interpreted as the
Dirac-Kahler matter fermions.Comment: 22 pages, LaTe
Note on Dirac--K\"ahler massless fields
We obtain the canonical and symmetrical Belinfante energy-momentum tensors of
Dirac--K\"{a}hler's fields. It is shown that the traces of the energy-momentum
tensors are not equal to zero. We find the canonical and Belinfante dilatation
currents which are not conserved, but a new conserved dilatation current is
obtained. It is pointed out that the conformal symmetry is broken. The
canonical quantization is performed and the propagator of the massless fields
in the first-order formalism is found.Comment: 16 pages, minor corrections in the text, published versio
Comparing high-resolution gridded precipitation data with satellite rainfall estimates of TRMM_3B42 over Iran
To evaluate satellite rainfall estimates of Tropical Rain
Measurement Mission (TRMM) level 3 output (3B42) (TRMM_3B42) over Iran
(20°â€“45° N, 40°â€“65° E), we compared these data with
high-resolution gridded precipitation datasets (0.25°×0.25° latitude/longitude) based on rain gauges (Iran Synoptic gauges Version 0902
(IS0902)). Spatial distribution of mean annual and mean seasonal rainfall in
both IS0902 and TRMM_3B42 from 1998 to 2006 shows two main rainfall
patterns along the Caspian Sea and over the Zagros Mountains. Scatter plots
of annual average rainfall from IS0902 versus TRMM_3B42 for each 0.25°×0.25° grid cell
over the entire country (25°â€“40° N,
45°â€“60° E), along the Caspian Sea (35°â€“40° N, 48°â€“56° E), and
over the Zagros Mountains (28°â€“37° N, 46°â€“55° E)
were derived. For the entire country, the Caspian Sea region, and the Zagros
Mountains, TRMM_3B42 underestimates mean annual precipitation by 0.17,
0.39, and 0.15 mm day<sup>−1</sup>, respectively, and the mean annual rainfall
spatial correlation coefficients are 0.77, 0.57, and 0.75, respectively. The
mean annual precipitation temporal correlation coefficient for IS0902 and
TRMM_3B42 is ~0.8 in the area along the Zagros Mountains, and ~0.6
in the Caspian Sea and desert regions
Species Doublers as Super Multiplets in Lattice Supersymmetry: Exact Supersymmetry with Interactions for D=1 N=2
We propose a new lattice superfield formalism in momentum representation
which accommodates species doublers of the lattice fermions and their bosonic
counterparts as super multiplets. We explicitly show that one dimensional N=2
model with interactions has exact Lie algebraic supersymmetry on the lattice
for all super charges. In coordinate representation the finite difference
operator is made to satisfy Leibnitz rule by introducing a non local product,
the ``star'' product, and the exact lattice supersymmetry is realized. The
standard momentum conservation is replaced on the lattice by the conservation
of the sine of the momentum, which plays a crucial role in the formulation.
Half lattice spacing structure is essential for the one dimensional model and
the lattice supersymmetry transformation can be identified as a half lattice
spacing translation combined with alternating sign structure. Invariance under
finite translations and locality in the continuum limit are explicitly
investigated and shown to be recovered. Supersymmetric Ward identities are
shown to be satisfied at one loop level. Lie algebraic lattice supersymmetry
algebra of this model suggests a close connection with Hopf algebraic exactness
of the link approach formulation of lattice supersymmetry.Comment: 34 pages, 2 figure
Formulation of Supersymmetry on a Lattice as a Representation of a Deformed Superalgebra
The lattice superalgebra of the link approach is shown to satisfy a Hopf
algebraic supersymmetry where the difference operator is introduced as a
momentum operator. The breakdown of the Leibniz rule for the lattice difference
operator is accommodated as a coproduct operation of (quasi)triangular Hopf
algebra and the associated field theory is consistently defined as a braided
quantum field theory. Algebraic formulation of path integral is perturbatively
defined and Ward-Takahashi identity can be derived on the lattice. The claimed
inconsistency of the link approach leading to the ordering ambiguity for a
product of fields is solved by introducing an almost trivial braiding structure
corresponding to the triangular structure of the Hopf algebraic superalgebra.
This could be seen as a generalization of spin and statistics relation on the
lattice. From the consistency of this braiding structure of fields a grading
nature for the momentum operator is required.Comment: 45 page
Abelian Dominance of Chiral Symmetry Breaking in Lattice QCD
Calculations of the chiral condensate on the lattice using staggered fermions
and the Lanczos algorithm are presented. Four gauge fields are considered: the
quenched non-Abelian field, an Abelian projected field, and monopole and photon
fields further decomposed from the Abelian field. Abelian projection is
performed in maximal Abelian gauge and in Polyakov gauge. The results show that
monopoles in maximal Abelian gauge largely reproduce the chiral condensate
values of the full non-Abelian theory, in both SU(2) and SU(3) color.Comment: 13 pages in RevTex including 6 figures, uucompressed, self-extractin
Inhomogeneous superconductivity in organic conductors: role of disorder and magnetic field
Several experimental studies have shown the presence of spatially
inhomogeneous phase coexistence of superconducting and non superconducting
domains in low dimensional organic superconductors. The superconducting
properties of these systems are found to be strongly dependent on the amount of
disorder introduced in the sample regardless of its origin. The suppression of
the superconducting transition temperature shows clear discrepancy with
the result expected from the Abrikosov-Gor'kov law giving the behavior of
with impurities. Based on the time dependent Ginzburg-Landau theory, we derive
a model to account for the striking feature of in organic superconductors
for different types of disorder by considering the segregated texture of the
system. We show that the calculated quantitatively agrees with
experiments. We also focus on the role of superconducting fluctuations on the
upper critical fields of layered superconductors showing slab
structure where superconducting domains are sandwiched by non-superconducting
regions. We found that may be strongly enhanced by such fluctuations.Comment: to appear in Journal of Physics: Condensed Matte
Reversible Metal-Semiconductor Transition of ssDNA-Decorated Single-Walled Carbon Nanotubes
A field effect transistor (FET) measurement of a SWNT shows a transition from
a metallic one to a p-type semiconductor after helical wrapping of DNA. Water
is found to be critical to activate this metal-semiconductor transition in the
SWNT-ssDNA hybrid. Raman spectroscopy confirms the same change in electrical
behavior. According to our ab initio calculations, a band gap can open up in a
metallic SWNT with wrapped ssDNA in the presence of water molecules due to
charge transfer.Comment: 13 pages, 6 figure
Dynamical Wilson fermions and the problem of the chiral limit in compact lattice QED
We compare the approach to the chiral transition line ~\kappa_c(\bt)~ in
quenched and full compact lattice QED with Wilson fermions within the
confinement phase, especially in the pseudoscalar sector of the theory. We show
that in the strong coupling limit () the quenched theory is a good
approximation to the full one, in contrast to the case of . At the
larger -value the transition in the full theory is inconsistent with the
zero--mass limit of the pseudoscalar particle, thus prohibiting the definition
of a chiral limit.Comment: 13 pages LaTeX (epsf), all figures include
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