343 research outputs found
Topcolor breaking through boundary conditions
The nontrivial boundary conditions (BC's) for the Topcolor breaking are
investigated in the context of the TeV-scale extra dimension scenario. In the
gauge symmetry breaking mechanism via the BC's we do not need to incorporate a
dynamical mechanism for the Topcolor breaking into the model. Moreover, the
Topcolor breaking can be realized without introducing explicitly a (composite)
scalar field. We present a six dimensional model where the top and bottom
quarks in the bulk have the Topcolor charge while the other quarks in the bulk
do not. We also put the electroweak gauge interaction in the six dimensional
bulk. The bottom quark condensation is naturally suppressed owing to the
power-like running of the bulk U(1)_Y interaction, so that only the top
condensation is expected to take place. We explore such a possibility based on
the ladder Schwinger-Dyson equation and show the cutoff to make the model
viable.Comment: 12 pages, 2 figures. Version to be published in Physical Review D.
Typos correcte
Competing states for the fractional quantum Hall effect in the 1/3-filled second Landau level
In this work, we investigate the nature of the fractional quantum Hall state
in the 1/3-filled second Landau level (SLL) at filling factor (and
8/3 in the presence of the particle-hole symmetry) via exact diagonalization in
both torus and spherical geometries. Specifically, we compute the overlap
between the exact 7/3 ground state and various competing states including (i)
the Laughlin state, (ii) the fermionic Haffnian state, (iii) the
antisymmetrized product state of two composite fermion seas at 1/6 filling, and
(iv) the particle-hole (PH) conjugate of the parafermion state. All these
trial states are constructed according to a guiding principle called the
bilayer mapping approach, where a trial state is obtained as the
antisymmetrized projection of a bilayer quantum Hall state with interlayer
distance as a variational parameter. Under the proper understanding of the
ground-state degeneracy in the torus geometry, the parafermion state can
be obtained as the antisymmetrized projection of the Halperin (330) state.
Similarly, it is proved in this work that the fermionic Haffnian state can be
obtained as the antisymmetrized projection of the Halperin (551) state. It is
shown that, while extremely accurate at sufficiently large positive Haldane
pseudopotential variation , the Laughlin state loses its
overlap with the exact 7/3 ground state significantly at . At slightly negative , it is shown that the
PH-conjugated parafermion state has a substantial overlap with the exact
7/3 ground state, which is the highest among the above four trial states.Comment: 22 pages, 5 figure
Jacobsthal identity for Q(√ - 2)
Let p be a prime congruent to 1 or 3 modulo 8 so that the equation p = a 2 C 2b 2 is solvable in integers. In this paper, we obtain closed-form expressions for a and b in terms of Jacobsthal sums. This is analogous to a classical identity of Jacobsthal. © de Gruyter 2012
Neutrino self-interaction and MSW effects on the supernova neutrino-process
We calculate the abundances of Li, B, Nb, Tc,
La, and Ta produced by neutrino induced reactions in a
core-collapse supernova explosion. We consider the modification by
self-interaction (-SI) near the neutrinosphere and the
Mikheyev-Smirnov-Wolfenstein effect in outer layers for time-dependent neutrino
energy spectra. Abundances of Li and heavy isotopes Nb, Tc
and La are reduced by a factor of 1.5-2.0 by the -SI. In contrast,
B is relatively insensitive to the -SI. We find that the abundance
ratio of heavy to light nucleus, La/B, is sensitive to the
neutrino mass hierarchy, and the normal mass hierarchy is more likely to be
consistent with the solar abundances
Techni-dilaton as Dark Matter
We propose a new dark matter candidate, {\it light decoupled techni-dilaton},
which arises from the almost scale-invariant/conformal (walking) technicolor.
We investigate its characteristic nature and discuss several cosmological and
astrophysical constraints. It turns out that techni-dilatons are extremely
weakly interacting and produced dominantly by the non-thermal mechanism to be
the main component of dark matter with mass range between around 0.01 eV and
500 eV for typical walking technicolor scenarios.Comment: 6 pages, 2 figures; version to appear in PL
1/16-BPS Black Holes and Giant Gravitons in the AdS_5 X S^5 Space
We explore 1/16-BPS objects of type IIB string theory in AdS_5 * S^5. First,
we consider supersymmetric AdS_5 black holes, which should be 1/16-BPS and have
a characteristic that not all physical charges are independent. We point out
that the Bekenstein-Hawking entropy of these black holes admits a remarkably
simple expression in terms of (dependent) physical charges, which suggests its
microscopic origin via certain Cardy or Hardy-Ramanujan formula. We also note
that there is an upper bound for the angular momenta given by the electric
charges. Second, we construct a class of 1/16-BPS giant graviton solutions in
AdS_5 * S^5 and explore their properties. The solutions are given by the
intersections of AdS_5 * S^5 and complex 3 dimensional holomorphic hyperspaces
in C^{1+5}, the latter being the zero loci of three holomorphic functions which
are homogeneous with suitable weights on coordinates. We investigate examples
of giant gravitons, including their degenerations to tensionless strings.Comment: 25 pages, no figures, v2: references added, comments added in the
conclusio
A weighted q-gram method for glycan structure classification
<p>Abstract</p> <p>Background</p> <p>Glycobiology pertains to the study of carbohydrate sugar chains, or glycans, in a particular cell or organism. Many computational approaches have been proposed for analyzing these complex glycan structures, which are chains of monosaccharides. The monosaccharides are linked to one another by glycosidic bonds, which can take on a variety of comformations, thus forming branches and resulting in complex tree structures. The <it>q</it>-gram method is one of these recent methods used to understand glycan function based on the classification of their tree structures. This <it>q</it>-gram method assumes that for a certain <it>q</it>, different <it>q</it>-grams share no similarity among themselves. That is, that if two structures have completely different components, then they are completely different. However, from a biological standpoint, this is not the case. In this paper, we propose a weighted <it>q</it>-gram method to measure the similarity among glycans by incorporating the similarity of the geometric structures, monosaccharides and glycosidic bonds among <it>q</it>-grams. In contrast to the traditional <it>q</it>-gram method, our weighted <it>q</it>-gram method admits similarity among <it>q</it>-grams for a certain <it>q</it>. Thus our new kernels for glycan structure were developed and then applied in SVMs to classify glycans.</p> <p>Results</p> <p>Two glycan datasets were used to compare the weighted <it>q</it>-gram method and the original <it>q</it>-gram method. The results show that the incorporation of <it>q</it>-gram similarity improves the classification performance for all of the important glycan classes tested.</p> <p>Conclusion</p> <p>The results in this paper indicate that similarity among <it>q</it>-grams obtained from geometric structure, monosaccharides and glycosidic linkage contributes to the glycan function classification. This is a big step towards the understanding of glycan function based on their complex structures.</p
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