770 research outputs found
ScannerS: Constraining the phase diagram of a complex scalar singlet at the LHC
We present the first version of a new tool to scan the parameter space of
generic scalar potentials, ScannerS. The main goal of ScannerS is to help
distinguish between different patterns of symmetry breaking for each scalar
potential. In this work we use it to investigate the possibility of excluding
regions of the phase diagram of several versions of a complex singlet extension
of the Standard Model, with future LHC results. We find that if another scalar
is found, one can exclude a phase with a dark matter candidate in definite
regions of the parameter space, while predicting whether a third scalar to be
found must be lighter or heavier. The first version of the code is publicly
available and contains various generic core routines for tree level vacuum
stability analysis, as well as implementations of collider bounds, dark matter
constraints, electroweak precision constraints and tree level unitarity.Comment: 24 pages, 4 figures, 3 tables. Project development webpage -
http://gravitation.web.ua.pt/Scanner
NLO electroweak corrections in general scalar singlet models
If no new physics signals are found, in the coming years, at the Large Hadron
Collider Run-2, an increase in precision of the Higgs couplings measurements
will shift the dicussion to the effects of higher order corrections. In Beyond
the Standard Model (BSM) theories this may become the only tool to probe new
physics. Extensions of the Standard Model (SM) with several scalar singlets may
address several of its problems, namely to explain dark matter, the
matter-antimatter asymmetry, or to improve the stability of the SM up to the
Planck scale. In this work we propose a general framework to calculate one
loop-corrections in BSM models with an arbitrary number of scalar singlets. We
then apply our method to a real and to a complex scalar singlet models. We
assess the importance of the one-loop radiative corrections first by computing
them for a tree level mixing sum constraint, and then for the main Higgs
production process . We conclude that, for the currently allowed
parameter space of these models, the corrections can be at most a few percent.
Notably, a non-zero correction can survive when dark matter is present, in the
SM-like limit of the Higgs couplings to other SM particles.Comment: 35 pages, 3 figure
Wrong sign and symmetric limits and non-decoupling in 2HDMs
We analyse the possibility that, in two Higgs doublet models, one or more of
the Higgs couplings to fermions or to gauge bosons change sign, relative to the
respective Higgs Standard Model couplings. Possible sign changes in the
coupling of a neutral scalar to charged ones are also discussed. These
\textit{wrong signs} can have important physical consequences, manifesting
themselves in Higgs production via gluon fusion or Higgs decay into two gluons
or into two photons. We consider all possible wrong sign scenarios, and also
the \textit{symmetric limit}, in all possible Yukawa implementations of the two
Higgs doublet model, in two different possibilities: the observed Higgs boson
is the lightest CP-even scalar, or the heaviest one. We also analyse thoroughly
the impact of the currently available LHC data on such scenarios. With all 8
TeV data analysed, all wrong sign scenarios are allowed in all Yukawa types,
even at the 1 level. However, we will show that B-physics constraints
are crucial in excluding the possibility of wrong sign scenarios in the case
where is below 1. We will also discuss the future prospects for
probing the wrong sign scenarios at the next LHC run. Finally we will present a
scenario where the alignment limit could be excluded due to non-decoupling in
the case where the heavy CP-even Higgs is the one discovered at the LHC.Comment: 20 pages, 15 figure
Temporal patterns in acoustic presence and foraging activity of oceanic dolphins at seamounts in the Azores
© The Author(s), 2020. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Cascao, I., Lammers, M. O., Prieto, R., Santos, R. S., & Silva, M. A. Temporal patterns in acoustic presence and foraging activity of oceanic dolphins at seamounts in the Azores. Scientific Reports, 10(1), (2020): 3610, doi:10.1038/s41598-020-60441-4.Several seamounts have been identified as hotspots of marine life in the Azores, acting as feeding stations for top predators, including cetaceans. Passive acoustic monitoring is an efficient tool to study temporal variations in the occurrence and behaviour of vocalizing cetacean species. We deployed bottom-moored Ecological Acoustic Recorders (EARs) to investigate the temporal patterns in acoustic presence and foraging activity of oceanic dolphins at two seamounts (Condor and Gigante) in the Azores. Data were collected in March–May 2008 and April 2010–February 2011. Dolphins were present year round and nearly every day at both seamounts. Foraging signals (buzzes and bray calls) were recorded in >87% of the days dolphin were present. There was a strong diel pattern in dolphin acoustic occurrence and behaviour, with higher detections of foraging and echolocation vocalizations during the night and of social signals during daylight hours. Acoustic data demonstrate that small dolphins consistently use Condor and Gigante seamounts to forage at night. These results suggest that these seamounts likely are important feeding areas for dolphins. This study contributes to a better understanding of the feeding ecology of oceanic dolphins and provides new insights into the role of seamount habitats for top predators.This research was supported by the Fundação para a Ciência e a Tecnologia (FCT), Azores 2020 Operational Programme and the Fundo Regional da Ciência e Tecnologia (FRCT), through research projects TRACE (PTDC/MAR/74071/2006), MAPCET (M2.1.2/F/012/2011), FCT-Exploratory (IF/00943/2013/CP1199/CT0001), WATCH IT (Acores-01-0145-FEDER-000057) and MISTIC SEAS II (GA11.0661/2017/750679/SUB/ENV.C2), co-funded by FEDER, COMPETE, QREN, POPH, European Social Fund (ESF), the Portuguese Ministry for Science and Education, and EU-DG/ENV. The Azores 2020 Operational Programme is funded by the community structural funds ERDF and ESF. Funds were also provided by FCT to MARE, through the strategic project UID/MAR/04292/2013. MAS was supported through a FCT Investigator contract funded by POPH, QREN, ESF and the Portuguese Ministry for Science and Education (IF/00943/2013). IC was supported by a FCT doctoral grant (SFRH/BD/41192/2007) and RP by a FCT postdoctoral grant (SFRH/BPD/108007/2015). We thank the field and crew teams for assisting with the many deployments and recoveries of the EARs. Special thanks to Norberto Serpa for helping with mooring design, Ken Sexton and Michael Richlen for their roles in manufacturing the EARs, Sergio Gomes for building the battery packs, and Lisa Munger for adapting Triton for EAR data analysis
The CP-conserving 2HDM after the 8 TeV run
We confront the most common CP-conserving 2HDM with the LHC data analysed so
far while taking into account all previously available experimental data. A
special allowed corner of the parameter space is analysed - the so-called
wrong-sign scenario where the Higgs coupling to down-type quarks changes sign
relative to the Standard Model while the coupling to the massive vector bosons
does not.Comment: 6 pages, 2 figures, to appear in the proceedings of the 22nd
International Workshop on Deep-Inelastic Scattering and Related Subjects (DIS
2014), 28 April - 2 May 2014 Warsaw (Poland
The Wrong Sign limit in the 2HDM
A sign change in the Higgs couplings to fermions and massive gauge bosons is
still allowed in the framework of two-Higgs doublet models (2HDM). In this work
we discuss the possible sign changes in the Higgs couplings to fermions and
gauge bosons, while reviewing the status of the 8-parameter CP-conserving 2HDM
after the Large Hadron Collider 8 TeV run.Comment: 6 pages, 3 figures. Proceedings of the Second Annual Conference on
Large Hadron Collider Physics, Columbia University, New York, U.S.A, June
2-7, 2014. arXiv admin note: text overlap with arXiv:1407.439
Impacts of climate change on the biogeography of three amnesic shellfish toxin producing diatom species
Harmful algal blooms (HABs) are considered one of the main risks for marine ecosystems and human health worldwide. Climate change is projected to induce significant changes in species geographic distribution, and, in this sense, it is paramount to accurately predict how it will affect toxin-producing microalgae. In this context, the present study was intended to project the potential biogeographical changes in habitat suitability and occurrence distribution of three key amnesic shellfish toxin (AST)-producing diatom species (i.e., Pseudo-nitzschia australis, P. seriata, and P. fraudulenta) under four different climate change scenarios (i.e., RCP-2.6, 4.5, 6.0, and 8.5) up to 2050 and 2100. For this purpose, we applied species distribution models (SDMs) using four abiotic predictors (i.e., sea surface temperature, salinity, current velocity, and bathymetry) in a MaxEnt framework. Overall, considerable contraction and potential extirpation were projected for all species at lower latitudes together with projected poleward expansions into higher latitudes, mainly in the northern hemisphere. The present study aims to contribute to the knowledge on the impacts of climate change on the biogeography of toxin-producing miinfo:eu-repo/semantics/publishedVersio
Projecting future climate change-mediated impacts in Three Paralytic Shellfish Toxins-Producing dinoflagellate species
Simple Summary Harmful algal blooms present a particular risk for marine ecosystems and human health alike. In this sense, it is important to accurately predict how toxin-producing microalgae could be affected by future climate change. The present study applied species distribution models (SDMs) to project the potential changes in the habitat suitability and distribution of three key paralytic shellfish toxin (PST)-producing dinoflagellate species (i.e., Alexandrium catenella, A. minutum, and Gymnodinium catenatum), up to 2040/50 and 2090/2100, across four different greenhouse gas emission scenarios, and using four abiotic predictors (i.e., sea surface temperature, salinity, current velocity, and bathymetry). In general, considerable contractions were observed for all three species in the lower latitudes of their distribution, together with projected expansions into higher latitudes, particularly in the Northern Hemisphere. This study aims to entice further research on the future biogeographical impacts of climate change in toxin-producing microalgae species while, at the same time, helping to advise the correct environmental management of coastal habitats and ecosystems. Toxin-producing microalgae present a significant environmental risk for ecosystems and human societies when they reach concentrations that affect other aquatic organisms or human health. Harmful algal blooms (HAB) have been linked to mass wildlife die-offs and human food poisoning episodes, and climate change has the potential to alter the frequency, magnitude, and geographical extent of such events. Thus, a framework of species distribution models (SDMs), employing MaxEnt modeling, was used to project changes in habitat suitability and distribution of three key paralytic shellfish toxin (PST)-producing dinoflagellate species (i.e., Alexandrium catenella, A. minutum, and Gymnodinium catenatum), up to 2050 and 2100, across four representative concentration pathway scenarios (RCP-2.6, 4.5, 6.0, and 8.5; CMIP5). Despite slightly different responses at the regional level, the global habitat suitability has decreased for all the species, leading to an overall contraction in their tropical and sub-tropical ranges, while considerable expansions are projected in higher latitudes, particularly in the Northern Hemisphere, suggesting poleward distributional shifts. Such trends were exacerbated with increasing RCP severity. Yet, further research is required, with a greater assemblage of environmental predictors and improved occurrence datasets, to gain a more holistic understanding of the potential impacts of climate change on PST-producing species.info:eu-repo/semantics/publishedVersio
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