5,545 research outputs found
S-Duality for D3-Brane in NS-NS and R-R Backgrounds
We construct the low-energy effective field theory for a D3-brane in constant
R-R 2-form potential background as the S-dual theory of a D3-brane in NS-NS
B-field background. Despite the non-Abelian algebra of the noncommutative U(1)
gauge symmetry, the electromagnetic duality transformation can be carried out
to all orders, and the dual Lagrangian is given in a compact form. The gauge
algebra is found to be a mixture of a deformed area-preserving diffeomorphism
and the usual U(1) gauge symmetry.Comment: 29 pages, minor change
Implications of the Little Higgs Dark Matter and T-odd Fermions
We study the phenomenology of dark matter in the Littlest Higgs model with
T-parity after the discovery of Higgs boson. We analyze the relic abundance of
dark matter, focusing on the effects of coannihilaitons with T-odd fermions.
After determining the parameter space that predicts the correct relic abundance
measured by WMAP and Planck collaborations, we evaluate the elastic scattering
cross section between dark matter and nucleon. In comparison with experimental
results, we find that the lower mass of dark matter is constrained mildly by
LUX 2013 while the future XENON experiment has potential to explore most of the
parameter space for both T-odd lepton and T-odd quark coannihilation scenarios.
We also study the collider signatures of T-odd fermion pair production at the
LHC. Even though the production cross sections are large, it turns out very
challenging to search for these T-odd fermions directly at the collider because
the visible charged leptons or jets are very soft. Furthermore, we show that,
with an extra hard jet radiated out from the initial state, the T-odd quark
pair production can contribute significantly to mono-jet plus missing energy
search at the LHC
Partition Function of Chiral Boson on 2-Torus from Floreanini-Jackiw Lagrangian
We revisit the problem of quantizing a chiral boson on a torus. The
conventional approach is to extract the partition function of a chiral boson
from the path integral of a non-chiral boson. Instead we compute it directly
from the chiral boson Lagrangian of Floreanini and Jackiw modified by
topological terms involving auxiliary fields. A careful analysis of the
gauge-fixing condition for the extra gauge symmetry reproduces the correct
results for the free chiral boson, and has the advantage of being applicable to
a wider class of interacting chiral boson theories.Comment: 31 pages, minor modificatio
Lagrangian Formulations of Self-dual Gauge Theories in Diverse Dimensions
In this work, we study Lagrangian formulations for self-dual gauge theories,
also known as chiral -form gauge theories, for in
dimensional spacetime. Motivated by a recent formulation of M5-branes derived
from the BLG model, we generalize the earlier Lagrangian formulation based on a
decomposition of spacetime into dimensions plus a special dimension, to
construct Lagrangian formulations based on a generic decomposition of spacetime
into and dimensions. Although the Lorentz symmetry is not
manifest, we prove that the action is invariant under modified Lorentz
transformations.Comment: 27 pages, the modified Lorentz transformation rule revised, minor
modification
Determinants and Impacts of the Relative Use of Depository Receipts and Euro Convertible Bonds by High-tech Corporations: An Empirical Study
This paper adopts Taiwan's high-tech companies as the sample to address and examine four new determinants of various foreign financing instruments and test their impacts on the issuing firms. Our empirical findings are consistent with the following notions. First, the firms with higher foreign holding and foreign investment will be likely to adopt foreign financing policy. Moreover, the firms with higher stock dividend payment in Taiwan will adopt both of ECB (Euro convertible bond) and DR (depository receipt). Firm managers with better education background will prefer DR. Second, the use of DR can effectively decrease the volatility of stock returns but also pronounce a negative influence on the mean of stock returns. In contrast, the use of ECB can effectively increase the mean but can not significantly decrease the volatility.
Design of nearest neighbor classifiers: multi-objective approach
AbstractThe goal of designing optimal nearest neighbor classifiers is to maximize classification accuracy while minimizing the sizes of both reference and feature sets. A usual way is to adaptively weight the three objectives as an objective function and then use a single-objective optimization method for achieving this goal. This paper proposes a multi-objective approach to cope with the weight tuning problem for practitioners. A novel intelligent multi-objective evolutionary algorithm IMOEA is utilized to simultaneously edit compact reference and feature sets for nearest neighbor classification. Three comparison studies are designed to evaluate performance of the proposed approach. It is shown empirically that the IMOEA-designed classifiers have high classification accuracy and small sizes of reference and feature sets. Moreover, IMOEA can provide a set of good solutions for practitioners to choose from in a single run. The simulation results indicate that the IMOEA-based approach is an expedient method to design nearest neighbor classifiers, compared with an existing single-objective approach
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