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Modélisation et analyse économique du comportement des acteurs sur les marchés énergétiques: Des producteurs aux consommateurs
No full textBenchmark for two-dimensional large scale coherent structures in partially magnetized E×B plasmas -Community collaboration & lessons learned
No full textLow-temperature plasmas are essential to both fundamental scientific research and critical industrial applications. As in many areas of science, numerical simulations have become a vital tool for uncovering new physical phenomena and guiding technological development. Code benchmarking remains crucial for verifying implementations and evaluating performance. This work continues the Landmark benchmark initiative, a series specifically designed to support the verification of low-temperature plasma codes. In this study, seventeen simulation codes from a collaborative community of nineteen international institutions modeled a partially magnetized E×B Penning discharge. The emergence of large scale coherent structures, or rotating plasma spokes, endows this configuration with an enormous range of time scales, making it particularly challenging to simulate. The codes showed excellent agreement on the rotation frequency of the spoke as well as key plasma properties, including time-averaged ion density, plasma potential, and electron temperature profiles. Achieving this level of agreement came with challenges, and we share lessons learned on how to conduct future benchmarking campaigns. Comparing code implementations, computational hardware, and simulation runtimes also revealed interesting trends, which are summarized with the aim of guiding future plasma simulation software development.</div
Search for exotic Higgs boson decays H with in events with a semi-merged topology in proton-proton collisions at = 13 TeV
No full textInternational audienceA search for exotic Higgs boson decays H , with is presented, using events with a semi-merged topology. One of the hypothetical particles, , is assumed to decay promptly into a semi-merged diphoton system reconstructed as a single photon-like object, while the other decays into two resolved photons. The search is performed using proton-proton collision data collected by the CMS experiment at = 13 TeV, corresponding to an integrated luminosity of 138 fb. The data agree with the standard model background expectation. Upper limits are set on the product of the Higgs boson production cross section and the branching fraction, (pp H)(H 4), which range from 0.264 to 0.005 pb at 95% confidence level, for masses in the range 1 15 GeV. These limits are the most stringent to date in the 15 GeV range
Search for charged Higgs bosons decaying into top and bottom quarks in lepton+jets final states in proton-proton collisions at = 13 TeV
No full textInternational audienceA search is presented for charged Higgs bosons (H) in proton-proton (pp) collision events via the pp (b)H processes, with H decaying into top (t) and bottom (b) quarks. The search targets final states with one lepton, missing transverse momentum, and two or more b jets. The analysis is based on data collected at a center-of-mass energy of 13 TeV with the CMS detector at the LHC, corresponding to an integrated luminosity of 138 fb. We search for charged Higgs bosons in the 200 GeV to 1 TeV mass range. The results are interpreted within the generalized two-Higgs-doublet model (g2HDM). This model predicts additional Yukawa couplings of the Higgs bosons to the top quark , the top and charm quark , and the top and up quark . This search focuses on the real components of and , which are probed up to values of unity. An excess is observed with respect to the standard model expectation with a local significance of 2.4 standard deviations for a signal with an H boson mass () of 600 GeV. Limits are derived on the product of the cross section (pp (b)H) and branching fraction (H tb, t b), where = e, . The values of 0.150.5 are excluded at 95% confidence level, depending on the and assumptions. The results represent the first search for charged Higgs bosons within the g2HDM framework and complement the existing results on additional neutral Higgs bosons
Machine-learning techniques for model-independent searches in dijet final states
No full textInternational audienceAnomaly detection methods used in a recent search for new phenomena by CMS at the CERN LHC are presented. The methods use machine learning to detect anomalous jets produced in the decay of new massive particles. The effectiveness of these approaches in enhancing sensitivity to various signals is studied and compared using data collected in proton-proton collisions at a center-of-mass energy of 13 TeV. In an example analysis, the capabilities of anomaly detection methods are further demonstrated by identifying large-radius jets consistent with Lorentz-boosted hadronically decaying top quarks in a model-agnostic framework
White paper on the relevance of the European Solar Telescope (EST) for the French heliophysics community
No full textThe project of the European Solar Telescope aims to provide a state-of-the art infrastructure to study the Sun and its interactions with Earth and the heliosphere. This 4.2m aperture telescope will be equipped with multi conjugate adaptive optics, light-polarisation analyser, imaging spectrograph and integral field unit spectrographs. It will provide unprecedented observations of the solar photosphere and chromosphere and of the dynamical events and features that pertains to the low solar atmosphere. The EST project is presently in a phase of crystallisation, aiming at the creation of an European Research Infrastructure Consortium. While the French community has continuously been associated with the development of the EST project, some specific scientific aspects are more particularly relevant for the French astrophysics and heliophysics communities. The present review highlights the scientific research axes of high interest from the French community that shall strongly benefit from EST. The later will not only advance numerous topics of solar physics, as well as solar adaptive optics developments, but will also provide unrivaled datasets of high interest in the framework of space weather. This review also aims to highlight the space weather use that can be done with future EST observations, that will be particularly relevant for French heliophysicists
Revealing photochemical processes using multiple timescale multiple probing visible transient absorption spectroscopy with two independent femtosecond amplifiers
No full textWe demonstrate that Arbitrary Detuning Asynchronous Optical Sampling (ADASOPS), a noninvasive method to perform multiple timescale transient absorption spectroscopy using two independent femtosecond amplifiers, can be combined with the technique known as multiple probing. We show that the time delay between a 1-kHz Ti:Sa femtosecond amplifier and a 125-kHz Yb femtosecond amplifier seeded by two free-running femtosecond oscillators can be controlled with a timing jitter better than ±8 ps. This method enables fast scanning of the time delay, with almost 1000 delays covering more than 8 decades scanned more than once per second, which in turns enables time alignment of consecutive scans resulting in a measured time resolution of about 500 fs FWHM. Additionally, multiple probing enables the acquisition of spectra corresponding to time delays multiples of 8 µs benefiting from an excellent signal-to-noise ratio thanks to the accumulation of a large number of laser shots. The potential of this technique is demonstrated with broadband visible transient absorption spectroscopy deciphering the photochemanism of two photo-active molecules, the benchmark intersystem crossing mechanism of copper(I) phenanthroline complexes and the fast photochromism of a novel phenoxyl-imidazolyl radical complex (PIC). For Copper(I) phenanthroline complexes this is the first transient absorption study that could catch the 4 species with three resolved lifetimes equal to 790 fs, 11.3 ps and 41 ns, while for PIC this is the first unambiguous observation, to our knowledge, of the picosecond dynamics of open-shell diradical to closed-shell quinoidal species before its relaxation in about 10 µs
Graph-based Asynchrony with Quasilinear Complexity for Any Linear Verifiable Secret Sharing Scheme
No full textVerifiable Secret Sharing (VSS) schemes usually consider synchronous communication, which cannot always be the case on real networks where packets can be lost or parties arbitrarily delayed. Allowing asynchrony adds a large overhead complexity cost: the dealer and communication complexity is in O(n²log(n)) in state of the art n-parties Asynchronous VSS (AVSS) schemes [ABD+25], whereas there are synchronous schemes with only linear communications. To ensure that all honest parties agree on the same secret and are ready for reconstruction, AVSS schemes essentially perform a protocol similar to Bracha’s broadcast [Bra87]. While this immediately bounds the overall communication complexity of the protocol to be at least in O(n²), this method enables to reach the maximum threshold of malicious parties of t=n/3. However, a smaller threshold t may be sufficient for some use cases, and one may want to take advantage of this. We consider a statistical scheme, meaning that the correctness and termination properties are only guaranteed with good probability. We propose a new method to transform any linear VSS scheme into a statistical AVSS. We build a statistical AVSS protocol Bonneval-on-Arc where each party only communicates with d neighbours, a situation that we model by a d-regular graph. We obtain quasilinear communication complexity for the dealer, and sublinear complexity for each party, and a corruption threshold t < n/(d + 2) as a tradeoff
Multidisciplinary science funding is more than ever a planetary priority: reflections from the Make Our Planet Great Again (MOPGA) program
No full textInternational audienceGlobal change poses “wicked problems” that have become ever more complex, pervasive, and damaging. Developing innovative solutions increasingly require diverse research approaches. The Franco-German Make Our Planet Great Again (MOPGA) program was designed to create a unique international network of top-level research, from fundamental to solution-oriented projects. MOPGA stands out from other large research initiatives by focusing not on a singular central research challenge but on facilitating multidisciplinary interactions between traditionally separated fields. MOPGA recognized that social, natural and engineering sciences share a unifying aim to address global change. In addition to addressing timely and innovative research questions within disciplines, MOPGA worked to improve communication across disciplines via annual meetings for all laureates and their research groups, scientific board exchanges, and public online seminars. Drawing on our MOPGA experiences, we discuss how such exchanges should be extended to meet the needs identified by the scientific community, international policy-makers, and regional stakeholders. In the current political landscape of scientific suppression and heightened mistrust in scientific expertise, the need for such bold, independent and collaborative scientific initiatives is greater than ever