351 research outputs found
Scrutinizing the Alignment Limit in Two-Higgs-Doublet Models. Part 2: GeV
In the alignment limit of a multi-doublet Higgs sector, one of the Higgs mass
eigenstates aligns in field space with the direction of the scalar field vacuum
expectation values, and its couplings approach those of the Standard Model (SM)
Higgs boson. We consider CP-conserving Two-Higgs-Doublet Models (2HDMs) of Type
I and Type II near the alignment limit in which the heavier of the two CP-even
Higgs bosons, , is the SM-like state observed with a mass of 125 GeV, and
the couplings of to gauge bosons approach those of the SM. We review the
theoretical structure and analyze the phenomenological implications of this
particular realization of the alignment limit, where decoupling of the extra
states cannot occur given that the lighter CP-even state must, by
definition, have a mass below 125 GeV. For the numerical analysis, we perform
scans of the 2HDM parameter space employing the software packages 2HDMC and
Lilith, taking into account all relevant pre-LHC constraints, constraints from
the measurements of the 125 GeV Higgs signal at the LHC, as well as the most
recent limits coming from searches for heavy Higgs-like states. Implications
for Run 2 at the LHC, including expectations for observing the other scalar
states, are also discussed.Comment: 44 pages, 27 figures; v2: references added, some updated constraint
Collider limits on new physics within micrOMEGAs4.3
Results from the LHC put severe constraints on models of new physics. This
includes constraints on the Higgs sector from the precise measurement of the
mass and couplings of the 125GeV Higgs boson, as well as limits from searches
for other new particles. We present the procedure to use these constraints in
micrOMEGAs by interfacing it to the external codes Lilith, HiggsSignals,
HiggsBounds and SModelS. A few dedicated modules are also provided. With these
new features, micrOMEGAs_4.3 provides a generic framework for evaluating dark
matter observables together with collider and non-collider constraints.Comment: 23 page
Light Higgs bosons in Two-Higgs-Doublet Models
We explore the possibilities in two-Higgs-doublet models (2HDMs) of Type I
and Type II for Higgs states with mass below about 60 GeV, i.e. less than half
of the ~125 GeV mass of the observed SM-like Higgs boson. We identify the
latter as either the lighter or the heavier CP-even state, h or H, and employ
scans of the 2HDM parameter space taking into account all relevant theoretical
and experimental constraints, including the most up-to-date Higgs signal
strength measurements. We find that, in both Type I and Type II models, such
light Higgs states are phenomenologically viable and can lead to interesting
signatures. Part of the relevant parameter space may be testable with the
existing 8 TeV LHC data, e.g. by looking for direct production of the light
state via gg-fusion or bb-associated-production using its \tau^+ \tau^- and
\mu^+ \mu^- decays at low invariant mass.Comment: 19 pages, 15 figures, references and a short comment adde
A mid-infrared Mueller ellipsometer with pseudo-achromatic optical elements
The purpose of this article is to present a new broadband Mueller
ellipsometer designed to work in the mid-infrared range, from 3 to 14 microns.
The Mueller ellipsometer, which can be mounted in reflection or in transmission
configuration, consists of a polarization state generator (PSG), a sample
holder, and a polarization state analyzer (PSA). The PSG consists in one linear
polarizer and a retarder sequentially rotated to generate a set of four optimal
polarization states. The retarder consists in a bi-prism made of two identical
Fresnel rhombs disposed symmetrically and joined by optical contact, giving the
ensemble a "V" shape. Retardation is induced by the four total internal
reflections that the beam undergoes when it propagates through the bi-prism.
Total internal reflection allows to generate a quasi-achromatic retardation.
The PSA is identical to the PSG, but with its optical elements mounted in
reverse order. After a measurement run, the instrument yields a set of sixteen
independent values, which is the minimum amount of data required to calculate
the Mueller matrix of the sample. The design of the Mueller ellipsometer is
based on the optimization of an objective criterion that allows minimizing the
propagation of errors from raw data to the Mueller matrix of the sample. The
pseudo-achromatic optical elements ensure a homogeneous quality of the
measurements for all wavelengths. The performance of the Mueller ellipsometer
in terms of precision, and accuracy, is discussed and illustrated with a few
examples
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Carbon brainprint - An estimate of the intellectual contribution of research institutions to reducing greenhouse gas emissions
This is the accepted manuscript of a paper published in Process Safety and Environmental Protection (Chatterton J, et al., Process Safety and Environmental Protection, 2015, 96, 74-81, doi:10.1016/j.psep.2015.04.008). The final version is available at http://dx.doi.org/10.1016/j.psep.2015.04.008Research and innovation have considerable, currently unquantified potential to reduce greenhouse gas emissions by, for example, increasing energy efficiency. Furthermore, the process of knowledge transfer in itself can have a significant impact on reducing emissions, by promoting awareness and behavioural change. The concept of the âcarbon brainprintâ was proposed to convey the intellectual contribution of higher education institutions to the reduction of greenhouse gas emissions by other parties through research and teaching/training activities. This paper describes an investigation of the feasibility of quantifying the carbon brainprint, through six case studies. The potential brainprint of higher education institutes is shown to be significant: up to 500 kt CO2e/year for one project. The most difficult aspect is attributing the brainprint among multiple participants in joint projects.The Carbon Brainprint project was supported by the Higher Education Funding Council for England (HEFCE) under its Leading Sustainable Development in Higher Education programme, with support for case studies from Santander Universities. HEFCE, Research Councils UK and the Carbon Trust were members of the Steering Committee, which provided guidance, but did not direct the research. The Carbon Trust also advised on best practice in carbon footprinting.
We are grateful to the many university staff at Cranfield, Cambridge and Reading Universities who shared their work with us so enthusiastically.
We also thank the external partners and clients for the projects on which these case studies are based: Rolls-Royce plc, the ETI NOVA consortium, IGD, the Environment Agency, Esso, Repsol YPF, Carnego Systems Ltd. and Newera Controls Ltd
A generic testing framework for agent-based simulation models
International audienceAgent-based modelling and simulation (ABMS) had an increasing attention during the last decade. However, the weak validation and verification of agent-based simulation models makes ABMS hard to trust. There is no comprehensive tool set for verification and validation of agent-based simulation models, which demonstrates that inaccuracies exist and/or reveals the existing errors in the model. Moreover, on the practical side, many ABMS frameworks are in use. In this sense, we designed and developed a generic testing framework for agent-based simulation models to conduct validation and verification of models. This paper presents our testing framework in detail and demonstrates its effectiveness by showing its applicability on a realistic agent-based simulation case study
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