Search results for "SCALAR"
showing 10 items of 1002 documents
Relation between quasirigidity andL-rigidity in space-times of constant curvature and weak fields
1997
The relation between quasirigidity andL-rigidity in space-times of constant nonzero curvature and in space-times with small curvature (weak fields) is studied. The covariant expansion of bitensors about a point is considered. We obtain an increase in the order of magnitude, underL-rigidity conditions, of the rate of change with respect to a comoving orthonormal frame of the linear momentum, angular momentum, and reduced multipole moments of the energy-momentum tensor. Thus,L-rigidity leads to quasirigidity in such space-times.
Towards Stable Radial Basis Function Methods for Linear Advection Problems
2021
In this work, we investigate (energy) stability of global radial basis function (RBF) methods for linear advection problems. Classically, boundary conditions (BC) are enforced strongly in RBF methods. By now it is well-known that this can lead to stability problems, however. Here, we follow a different path and propose two novel RBF approaches which are based on a weak enforcement of BCs. By using the concept of flux reconstruction and simultaneous approximation terms (SATs), respectively, we are able to prove that both new RBF schemes are strongly (energy) stable. Numerical results in one and two spatial dimensions for both scalar equations and systems are presented, supporting our theoret…
Soliton generation and rogue-wave like behavior through fourth order modulation instability
2010
International audience; We numerically study the dynamics of ultra-broadband wavelength converters based on fourth-order scalar modulation instability. We report the spontaneous emergence of solitons and trapped radiation waves as well as L-shaped associated statistical signatures.
New exclusion limits on scalar and pseudoscalar axionlike particles from light shining through a wall
2015
Physics beyond the Standard Model predicts the possible existence of new particles that can be searched at the low-energy frontier in the sub-eV range. The OSQAR photon regeneration experiment looks for ``light shining through a wall'' from the quantum oscillation of optical photons into ``weakly interacting sub-eV particles,'' such as axion or axionlike particles (ALPs) in a 9 T transverse magnetic field over a length of $2\ifmmode\times\else\texttimes\fi{}14.3\text{ }\text{ }\mathrm{m}$. In 2014, this experiment was run with an outstanding sensitivity, using an 18.5 W continuous wave laser emitting in the green at the single wavelength of 532 nm. No regenerated photons have been detected …
An interactive surrogate-based method for computationally expensive multiobjective optimisation
2019
Many disciplines involve computationally expensive multiobjective optimisation problems. Surrogate-based methods are commonly used in the literature to alleviate the computational cost. In this paper, we develop an interactive surrogate-based method called SURROGATE-ASF to solve computationally expensive multiobjective optimisation problems. This method employs preference information of a decision-maker. Numerical results demonstrate that SURROGATE-ASF efficiently provides preferred solutions for a decision-maker. It can handle different types of problems involving for example multimodal objective functions and nonconvex and/or disconnected Pareto frontiers. peerReviewed
Scales of participation and multi-scalar citizenship in EU participatory governance
2020
The EU still has a democratic deficit and its legitimacy is strongly questioned. This reveals the importance of citizenship and participation in the context of the challenges the EU faces today. The article contributes to the current discussions on the shifting frameworks of participation and citizenship through empirical research into the EU’s participatory governance. It asks how participation is framed in terms of scale and how these scalar framings are used to formulate citizenship in selected projects funded by the EU programmes on citizenship and culture. This microlevel analysis yields new insights into the politics of scale in the EU’s multilevel participatory governance. Frame anal…
Upper limits on the isotropic gravitational-wave background from Advanced LIGO and Advanced Virgo's third observing run
2021
We report results of a search for an isotropic gravitational-wave background (GWB) using data from Advanced LIGO's and Advanced Virgo's third observing run (O3) combined with upper limits from the earlier O1 and O2 runs. Unlike in previous observing runs in the advanced detector era, we include Virgo in the search for the GWB. The results are consistent with uncorrelated noise, and therefore we place upper limits on the strength of the GWB. We find that the dimensionless energy density $\Omega_{\rm GW}\leq 5.8\times 10^{-9}$ at the 95% credible level for a flat (frequency-independent) GWB, using a prior which is uniform in the log of the strength of the GWB, with 99% of the sensitivity comi…
Hunting for new physics signals in the LHC era
2021
Actualment, el ME de física de partícules és capaç d’explicar satisfactòriament tres de les quatre interaccions fonamentals de la matèria: fortes, febles i electromagnètiques. Tot i això, hi han molts aspectes que aquesta fantàstica teoria no és capaç d’explicar i, sens dubte, ha d’haver alguna cosa més enllà d’aquesta teoria. En aquesta tesi es pretén descobrir si hi ha algun indici a les dades actuals dels acceleradors que suggerisca l’existència de nova física (NF). Pretenem, per tant, determinar fins a quin punt alguns dels models de NF que han sigut proposats a la literatura poden ser plausibles tenint en compte les dades actuals. D’aquesta forma, serem capaços de trobar restriccions s…
A strong electroweak phase transition from the inflaton field
2016
We study a singlet scalar extension of the Standard Model. The singlet scalar is coupled non-minimally to gravity and assumed to drive inflation, and also couple sufficiently strongly with the SM Higgs field in order to provide for a strong first order electroweak phase transition. Requiring the model to describe inflation successfully, be compatible with the LHC data, and yield a strong first order electroweak phase transition, we identify the regions of the parameter space where the model is viable. We also include a singlet fermion with scalar coupling to the singlet scalar to probe the sensitivity of the constraints on additional degrees of freedom and their couplings in the singlet sec…
Complete One-Loop Renormalization of the Higgs-Electroweak Chiral Lagrangian
2018
The electroweak sector of the Standard Model can be formulated in a way similar to Chiral Perturbation Theory (ChPT), but extended by a singlet scalar. The resulting effective field theory (EFT) is called Higgs-Electroweak Chiral Lagrangian (EWCh$\mathcal{L}$) and is the most general approach to new physics in the Higgs sector. It solely assumes the pattern of symmetry breaking leading to the three electroweak Goldstone bosons (i.e. massive $W$ and $Z$) and the existence of a Higgs-like scalar particle. The power counting of the EWCh$\mathcal{L}$ is given by a generalization of the momentum expansion of ChPT. It is connected to a loop expansion, making the theory renormalizable order by ord…