664,329 research outputs found

### Transfer Matrices for the Partition Function of the Potts Model on Toroidal Lattice Strips

We present a method for calculating transfer matrices for the $q$-state Potts
model partition functions $Z(G,q,v)$, for arbitrary $q$ and temperature
variable $v$, on strip graphs $G$ of the square (sq), triangular (tri), and
honeycomb (hc) lattices of width $L_y$ vertices and of arbitrarily great length
$L_x$ vertices, subject to toroidal and Klein bottle boundary conditions. For
the toroidal case we express the partition function as $Z(\Lambda, L_y \times
L_x,q,v) = \sum_{d=0}^{L_y} \sum_j b_j^{(d)} (\lambda_{Z,\Lambda,L_y,d,j})^m$,
where $\Lambda$ denotes lattice type, $b_j^{(d)}$ are specified polynomials of
degree $d$ in $q$, $\lambda_{Z,\Lambda,L_y,d,j}$ are eigenvalues of the
transfer matrix $T_{Z,\Lambda,L_y,d}$ in the degree-$d$ subspace, and $m=L_x$
($L_x/2$) for $\Lambda=sq, tri (hc)$, respectively. An analogous formula is
given for Klein bottle strips. We exhibit a method for calculating
$T_{Z,\Lambda,L_y,d}$ for arbitrary $L_y$. In particular, we find some very
simple formulas for the determinant $det(T_{Z,\Lambda,L_y,d})$, and trace
$Tr(T_{Z,\Lambda,L_y})$. Corresponding results are given for the equivalent
Tutte polynomials for these lattice strips and illustrative examples are
included.Comment: 52 pages, latex, 10 figure

### Community detection for networks with unipartite and bipartite structure

Finding community structures in networks is important in network science,
technology, and applications. To date, most algorithms that aim to find
community structures only focus either on unipartite or bipartite networks. A
unipartite network consists of one set of nodes and a bipartite network
consists of two nonoverlapping sets of nodes with only links joining the nodes
in different sets. However, a third type of network exists, defined here as the
mixture network. Just like a bipartite network, a mixture network also consists
of two sets of nodes, but some nodes may simultaneously belong to two sets,
which breaks the nonoverlapping restriction of a bipartite network. The mixture
network can be considered as a general case, with unipartite and bipartite
networks viewed as its limiting cases. A mixture network can represent not only
all the unipartite and bipartite networks, but also a wide range of real-world
networks that cannot be properly represented as either unipartite or bipartite
networks in fields such as biology and social science. Based on this
observation, we first propose a probabilistic model that can find modules in
unipartite, bipartite, and mixture networks in a unified framework based on the
link community model for a unipartite undirected network [B Ball et al (2011
Phys. Rev. E 84 036103)]. We test our algorithm on synthetic networks (both
overlapping and nonoverlapping communities) and apply it to two real-world
networks: a southern women bipartite network and a human transcriptional
regulatory mixture network. The results suggest that our model performs well
for all three types of networks, is competitive with other algorithms for
unipartite or bipartite networks, and is applicable to real-world networks.Comment: 27 pages, 8 figures.
(http://iopscience.iop.org/1367-2630/16/9/093001

### On Exactly Solvable Potentials

We investigate two methods of obtaining exactly solvable potentials with
analytic forms.Comment: 13 pages, Latex, to appear in Chineses Journal of Physic

### Comparison of Support Vector Machine and Back Propagation Neural Network in Evaluating the Enterprise Financial Distress

Recently, applying the novel data mining techniques for evaluating enterprise
financial distress has received much research alternation. Support Vector
Machine (SVM) and back propagation neural (BPN) network has been applied
successfully in many areas with excellent generalization results, such as rule
extraction, classification and evaluation. In this paper, a model based on SVM
with Gaussian RBF kernel is proposed here for enterprise financial distress
evaluation. BPN network is considered one of the simplest and are most general
methods used for supervised training of multilayered neural network. The
comparative results show that through the difference between the performance
measures is marginal; SVM gives higher precision and lower error rates.Comment: 13 pages, 1 figur

### Transfer Matrices for the Zero-Temperature Potts Antiferromagnet on Cyclic and Mobius Lattice Strips

We present transfer matrices for the zero-temperature partition function of
the $q$-state Potts antiferromagnet (equivalently, the chromatic polynomial) on
cyclic and M\"obius strips of the square, triangular, and honeycomb lattices of
width $L_y$ and arbitrarily great length $L_x$. We relate these results to our
earlier exact solutions for square-lattice strips with $L_y=3,4,5$,
triangular-lattice strips with $L_y=2,3,4$, and honeycomb-lattice strips with
$L_y=2,3$ and periodic or twisted periodic boundary conditions. We give a
general expression for the chromatic polynomial of a M\"obius strip of a
lattice $\Lambda$ and exact results for a subset of honeycomb-lattice transfer
matrices, both of which are valid for arbitrary strip width $L_y$. New results
are presented for the $L_y=5$ strip of the triangular lattice and the $L_y=4$
and $L_y=5$ strips of the honeycomb lattice. Using these results and taking the
infinite-length limit $L_x \to \infty$, we determine the continuous
accumulation locus of the zeros of the above partition function in the complex
$q$ plane, including the maximal real point of nonanalyticity of the degeneracy
per site, $W$ as a function of $q$.Comment: 62 pages, latex, 6 eps figures, includes additional results, e.g.,
loci ${\cal B}$, requested by refere

### BCVEGPY: An Event Generator for Hadronic Production of the B_c Meson

We have written a Fortran programme BCVEGPY, which is an event generator for
the hadronic production of the $B_c$ meson through the dominant hard subprocess
$gg\to B_c(B_c^*) +b+\bar{c}$. To achieve a compact programme, we have written
the amplitude of the subprocess with the particle helicity technique and made
it as symmetric as possible, by decomposing the gluon self couplings and then
applying the symmetries. To check the programme, various cross sections of the
subprocess have been computed numerically and compared with those in the
literature. BCVEGPY is written in a PYTHIA-compatible format, thus it is easy
to implement in PYTHIA.Comment: 47 pages, 12 figure

### Chiral Restoration in the Early Universe: Pion Halo in the Sky

vanishing above $T_c$ indicates chiral symmetry restoration at
high $T$. But is it the old $T=0$ chiral symmetry that is `restored'? In this
talk, I report on the spacetime quantization of the BPFTW effective action for
quarks in a hot environ. The fermion propagator is known to give a
pseudo-Lorentz invariant particle pole as well as new spacelike cuts. Our
quantization shows that the spacelike cuts directly lead to a thermal vacuum
that is a generalized NJL state, with a curious $90^{o}$ phase. This $90^{o}$
is responsible for vanishing at high $T$. The thermal vacuum is
invariant under a new chiral charge, but continues to break the old zero
temperature chirality. Our quantization suggests a new class of order
parameters that probe the physics of these spacelike cuts. In usual scenario,
the pion dissociates in the early alphabet soup. With this new understanding of
the thermal vacuum, the pion remains a Nambu-Goldstone particle at high $T$,
and will not dissociate. It propagates at the speed of light but with a halo.Comment: 4 pages, LaTeX, CCNY-HEP-94-9 To appear in Proceedings of "Trends in
Astroparticle Physics Workshop", Stockholm, Sweden, 22-25 September, 1994,
Nuclear Physics B, Proceedings Supplement, edited by L. Bergstrom, P.
Carlson, P.O. Hulth, and H. Snellman. (Only revision is in the header
citation

### Electron Electric Dipole Moment induced by Octet-Colored Scalars

An appended sector of two octet-colored scalars, each an electroweak doublet,
is an interesting extension of the simple two Higgs doublet model motivated by
the minimal flavor violation. Their rich CP violating interaction gives rise to
a sizable electron electric dipole moment, besides the quark electric dipole
moment via the two-loop contribution of Barr-Zee mechanism.Comment: 8 pages, 2 figure

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