47 research outputs found
Finite flavour groups of fermions
We present an overview of the theory of finite groups, with regard to their
application as flavour symmetries in particle physics. In a general part, we
discuss useful theorems concerning group structure, conjugacy classes,
representations and character tables. In a specialized part, we attempt to give
a fairly comprehensive review of finite subgroups of SO(3) and SU(3), in which
we apply and illustrate the general theory. Moreover, we also provide a concise
description of the symmetric and alternating groups and comment on the
relationship between finite subgroups of U(3) and finite subgroups of SU(3).
Though in this review we give a detailed description of a wide range of finite
groups, the main focus is on the methods which allow the exploration of their
different aspects.Comment: 89 pages, 6 figures, some references added, rearrangement of part of
the material, section on SU(3) subgroups substantially extended, some minor
revisions. Version for publication in J. Phys. A. Table 12 corrected to match
eq.(256), table 14 and eq.(314) corrected to match the 2-dimensional irreps
defined on p.6
Principal series of finite subgroups of SU(3)
We attempt to give a complete description of the "exceptional" finite
subgroups Sigma(36x3), Sigma(72x3) and Sigma(216x3) of SU(3), with the aim to
make them amenable to model building for fermion masses and mixing. The
information on these groups which we derive contains conjugacy classes, proper
normal subgroups, irreducible representations, character tables and tensor
products of their three-dimensional irreducible representations. We show that,
for these three exceptional groups, usage of their principal series, i.e.
ascending chains of normal subgroups, greatly facilitates the computations and
illuminates the relationship between the groups. As a preparation and testing
ground for the usage of principal series, we study first the dihedral-like
groups Delta(27) and Delta(54) because both are members of the principal series
of the three groups discussed in the paper.Comment: 43 pages, no figures; typos corrected, clarifications and references
added, version matches publication in J. Phys.
DeltaPhish: Detecting Phishing Webpages in Compromised Websites
The large-scale deployment of modern phishing attacks relies on the automatic
exploitation of vulnerable websites in the wild, to maximize profit while
hindering attack traceability, detection and blacklisting. To the best of our
knowledge, this is the first work that specifically leverages this adversarial
behavior for detection purposes. We show that phishing webpages can be
accurately detected by highlighting HTML code and visual differences with
respect to other (legitimate) pages hosted within a compromised website. Our
system, named DeltaPhish, can be installed as part of a web application
firewall, to detect the presence of anomalous content on a website after
compromise, and eventually prevent access to it. DeltaPhish is also robust
against adversarial attempts in which the HTML code of the phishing page is
carefully manipulated to evade detection. We empirically evaluate it on more
than 5,500 webpages collected in the wild from compromised websites, showing
that it is capable of detecting more than 99% of phishing webpages, while only
misclassifying less than 1% of legitimate pages. We further show that the
detection rate remains higher than 70% even under very sophisticated attacks
carefully designed to evade our system.Comment: Preprint version of the work accepted at ESORICS 201
Abelian symmetries in multi-Higgs-doublet models
N-Higgs doublet models (NHDM) are a popular framework to construct
electroweak symmetry breaking mechanisms beyond the Standard model. Usually,
one builds an NHDM scalar sector which is invariant under a certain symmetry
group. Although several such groups have been used, no general analysis of
symmetries possible in the NHDM scalar sector exists. Here, we make the first
step towards this goal by classifying the elementary building blocks, namely
the abelian symmetry groups, with a special emphasis on finite groups. We
describe a strategy that identifies all abelian groups which are realizable as
symmetry groups of the NHDM Higgs potential. We consider both the groups of
Higgs-family transformations only and the groups which also contain generalized
CP transformations. We illustrate this strategy with the examples of 3HDM and
4HDM and prove several statements for arbitrary N.Comment: 33 pages, 2 figures; v2: conjecture 3 is proved and becomes theorem
3, more explanations of the main strategy are added, matches the published
versio
Proceedings of the 2nd Workshop on Flavor Symmetries and Consequences in Accelerators and Cosmology (FLASY12)
These are the proceedings of the 2nd Workshop on Flavor Symmetries and
Consequences in Accelerators and Cosmology, held 30 June 2012 - 4 July 2012,
Dortmund, Germany.Comment: Order 400 pages, several figures including the group picture v2:
corrected author list and contributio
Theory of Neutrino Masses and Mixing
We motivate the usage of finite groups as symmetries of the Lagrangian. After
a presentation of basic group-theoretical concepts, we introduce the notion of
characters and character tables in the context of irreducible representations
and discuss their applications. We exemplify these theoretical concepts with
the groups S_4 and A_4. Finally, we discuss the relation between tensor
products of irreducible representations and Yukawa couplings and describe a
model for tri-bimaximal lepton mixing based on A_4.Comment: 23 pages, lecture presented at IV International Pontecorvo Neutrino
Physics School, September 26 - October 6, 2010, Alushta, Crimea, Ukrain
A P2P Botnet detection scheme based on decision tree and adaptive multilayer neural networks
In recent years, Botnets have been adopted as a popular method to carry and spread many malicious codes on the Internet. These malicious codes pave the way to execute many fraudulent activities including spam mail, distributed denial-of-service attacks and click fraud. While many Botnets are set up using centralized communication architecture, the peer-to-peer (P2P) Botnets can adopt a decentralized architecture using an overlay network for exchanging command and control data making their detection even more difficult. This work presents a method of P2P Bot detection based on an adaptive multilayer feed-forward neural network in cooperation with decision trees. A classification and regression tree is applied as a feature selection technique to select relevant features. With these features, a multilayer feed-forward neural network training model is created using a resilient back-propagation learning algorithm. A comparison of feature set selection based on the decision tree, principal component analysis and the ReliefF algorithm indicated that the neural network model with features selection based on decision tree has a better identification accuracy along with lower rates of false positives. The usefulness of the proposed approach is demonstrated by conducting experiments on real network traffic datasets. In these experiments, an average detection rate of 99.08 % with false positive rate of 0.75 % was observed