797 research outputs found
Patterns of Strong Coupling for LHC Searches
Even though the Standard Model (SM) is weakly coupled at the Fermi scale, a
new strong dynamics involving its degrees of freedom may conceivably lurk at
slightly higher energies, in the multi TeV range. Approximate symmetries
provide a structurally robust context where, within the low energy description,
the dimensionless SM couplings are weak, while the new strong dynamics
manifests itself exclusively through higher-derivative interactions. We present
an exhaustive classification of such scenarios in the form of effective field
theories, paying special attention to new classes of models where the strong
dynamics involves, along with the Higgs boson, the SM gauge bosons and/or the
fermions. The IR softness of the new dynamics suppresses its effects at LEP
energies, but deviations are in principle detectable at the LHC, even at
energies below the threshold for production of new states. Our construction
provides the so far unique structurally robust context where to motivate
several searches in Higgs physics, diboson production, or WW scattering, which
were so far poorly justified. Perhaps surprisingly, the interplay between weak
coupling, strong coupling and derivatives, which is controlled by symmetries,
can override the naive expansion in operator dimension, providing instances
where dimension-8 dominates dimension-6, well within the domain of validity of
the low energy effective theory. This result reveals the limitations of an
analysis that is both ambitiously general and restricted to dimension-6
operators.Comment: 37 pages, 1 figur
(Re-)Inventing the Relativistic Wheel: Gravity, Cosets, and Spinning Objects
Space-time symmetries are a crucial ingredient of any theoretical model in
physics. Unlike internal symmetries, which may or may not be gauged and/or
spontaneously broken, space-time symmetries do not admit any ambiguity: they
are gauged by gravity, and any conceivable physical system (other than the
vacuum) is bound to break at least some of them. Motivated by this observation,
we study how to couple gravity with the Goldstone fields that non-linearly
realize spontaneously broken space-time symmetries. This can be done in
complete generality by weakly gauging the Poincare symmetry group in the
context of the coset construction. To illustrate the power of this method, we
consider three kinds of physical systems coupled to gravity: superfluids,
relativistic membranes embedded in a higher dimensional space, and rotating
point-like objects. This last system is of particular importance as it can be
used to model spinning astrophysical objects like neutron stars and black
holes. Our approach provides a systematic and unambiguous parametrization of
the degrees of freedom of these systems.Comment: 30 page
High-resolution periodic mode shapes identification for wind turbines
The stability analysis of in-operation wind turbines is a very important topic, that has received considerable attention in the last years. Many identification algorithms have been developed to estimate frequencies and damping ratios, but very few papers have been dedicated to the mode shapes. The knowledge of high-resolution mode shapes could be exploited for several applications including model validation, accurate description of the vibratory content of a machine and spatially-accurate damage detection. In this work, we will present a procedure to compute the high-resolution periodic mode shapes of a wind turbine, and apply it to a high-fidelity wind turbine model. The results show that this methodology is able to identify the first low-damped modes of the system with good accuracy
Phenotypic and genotypic data integration and exploration through a web-service architecture
<p>Abstract</p> <p>Background</p> <p>Linking genotypic and phenotypic information is one of the greatest challenges of current genetics research. The definition of an Information Technology infrastructure to support this kind of studies, and in particular studies aimed at the analysis of complex traits, which require the definition of multifaceted phenotypes and the integration genotypic information to discover the most prevalent diseases, is a paradigmatic goal of Biomedical Informatics. This paper describes the use of Information Technology methods and tools to develop a system for the management, inspection and integration of phenotypic and genotypic data.</p> <p>Results</p> <p>We present the design and architecture of the Phenotype Miner, a software system able to flexibly manage phenotypic information, and its extended functionalities to retrieve genotype information from external repositories and to relate it to phenotypic data. For this purpose we developed a module to allow customized data upload by the user and a SOAP-based communications layer to retrieve data from existing biomedical knowledge management tools. In this paper we also demonstrate the system functionality by an example application of the system in which we analyze two related genomic datasets.</p> <p>Conclusion</p> <p>In this paper we show how a comprehensive, integrated and automated workbench for genotype and phenotype integration can facilitate and improve the hypothesis generation process underlying modern genetic studies.</p
Higgs Couplings in Composite Models
We study Higgs couplings in the composite Higgs model based on the coset
SO(5)/SO(4). We show that the couplings to gluons and photons are insensitive
to the elementary-composite mixings and thus not affected by light fermionic
resonances. Moreover, at leading order in the mixings the Higgs couplings to
tops and gluons, when normalized to the Standard Model (SM), are equal. These
properties are shown to be direct consequences of the Goldstone symmetry and of
the assumption of partial compositeness. In particular, they are independent of
the details of the elementary-composite couplings and, under the further
assumption of CP invariance, they are also insensitive to derivative
interactions of the Higgs with the composite resonances. We support our
conclusions with an explicit construction where the SM fermions are embedded in
the 14 dimensional representation of SO(5).Comment: 13 pages, 3 figures, 2 tables; v2: small improvements in the
discussion, results unchanged; typos corrected; one reference added. Matches
version submitted to PR
What is the gamma gamma resonance at 750 GeV?
Run 2 LHC data show hints of a new resonance in the diphoton distribution at
an invariant mass of 750 GeV. We analyse the data in terms of a new boson,
extracting information on its properties and exploring theoretical
interpretations. Scenarios covered include a narrow resonance and, as
preliminary indications suggest, a wider resonance. If the width indications
persist, the new particle is likely to belong to a strongly-interacting sector.
We also show how compatibility between Run 1 and Run 2 data is improved by
postulating the existence of an additional heavy particle, whose decays are
possibly related to dark matter.Comment: v2: 45 pages, 12 figures, final. Factor of 2 changed in table 1, 4th
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Periodic stability analysis of wind turbines operating in turbulent wind conditions
Abstract. The formulation is model-independent, in the sense that it does not require knowledge of the equations of motion of the periodic system being analyzed, and it is applicable to an arbitrary number of blades and to any configuration of the machine. In addition, as wind turbulence can be viewed as a stochastic disturbance, the method is also applicable to real wind turbines operating in the field. The characteristics of the new method are verified first with a simplified analytical model and then using a high-fidelity multi-body model of a multi-MW wind turbine. Results are compared with those obtained by the well-known operational modal analysis approach
An automated reasoning framework for translational research
AbstractIn this paper we propose a novel approach to the design and implementation of knowledge-based decision support systems for translational research, specifically tailored to the analysis and interpretation of data from high-throughput experiments. Our approach is based on a general epistemological model of the scientific discovery process that provides a well-founded framework for integrating experimental data with preexisting knowledge and with automated inference tools.In order to demonstrate the usefulness and power of the proposed framework, we present its application to Genome-Wide Association Studies, and we use it to reproduce a portion of the initial analysis performed on the well-known WTCCC dataset. Finally, we describe a computational system we are developing, aimed at assisting translational research. The system, based on the proposed model, will be able to automatically plan and perform knowledge discovery steps, to keep track of the inferences performed, and to explain the obtained results
On the wave equation on moving domains: regularity, energy balance and application to dynamic debonding
We revisit some issues about existence and regularity for the wave equation
in noncylindrical domains. Using a method of diffeomorphisms, we show how,
through increasing regularity assumptions, the existence of weak solutions,
their improved regularity and an energy balance can be derived. As an
application, we give a rigorous definition of dynamic energy release rate
density for some problems of debonding, and we formulate a proper notion of
solution for such problems. We discuss the consistence of such formulation with
previous ones, given in literature for particular cases.Comment: 36 page
Multi-parameter perturbations for the space periodic heat equation
This paper is divided into three parts. The first part focuses on periodic
layer heat potentials, demonstrating their smooth dependence on regular
perturbations of the support of integration. In the second part, we present an
application of the results from the first part. Specifically, we consider a
transmission problem for the heat equation in a periodic two-phase composite
material and we show that the solution depends smoothly on the shape of the
transmission interface, boundary data, and conductivity parameters. Finally, in
the last part of the paper, we fix all parameters except for the contrast
parameter and outline a strategy to deduce an explicit expansion of the
solution using a Neumann-type series
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