Recent results from fixed-target collisions at LHCb

Proceedings for Quark Matter 2023The LHCb spectrometer has the unique capability to function as a fixed-target experiment by injecting gas into the LHC beam pipe while proton or ion beams are circulating. The resulting beam+gas collisions cover an unexplored energy range, intermediate to previous fixed-target experiments and the top RHIC energy for AA collisions, and allow systems of different size to be studied. Here we present new results on open charm, J/ψ, and ψ(2S) production from pNe and PbNe fixed-target collisions at LHCb. Comparisons with various theoretical models of particle production and transport through the nucleus will be discussed

Les émissions de CO2 de l’industrie française et le « ciblage carbone » des politiques publiques

PrésentationQui sont les entreprises françaises qui contribuent le plus aux émissions de CO2 de l’industrie française, et quelles sont leurs caractéristiques ? Quels dispositifs de réduction des émissions de CO2 s’appliquent à elles, et selon quelles modalités ? Quel rôle insoupçonné peuvent avoir les outils fiscaux généraux, a priori sans visée environnementale ? Cette note répond successivement à ces trois questions, et propose un premier cadre d’analyse pour l’évaluation ex ante des mesures de politiques publiques à destination des entreprises. Nous documentons la distribution de l’intensité carbone dans le tissu industriel français, ainsi que les tarifications effectives du carbone auxquelles sont soumis différents types d’entreprises. Enfin, nous examinons le ciblage carbone implicite de différents dispositifs fiscaux sans visée environnementale.Résultats clésLes émissions de CO2 du secteur industriel sont extrêmement concentrées ; 10 % de la valeur ajoutée représentent 75 % des émissions de CO2.Cette forte concentration est en grande partie tirée par des effets sectoriels ; la métallurgie, la chimie, les minéraux métalliques (comme le ciment), et le papier/carton sont les secteurs les plus intenses en CO2.Deux grands régimes de tarification effective du CO2 cohabitent dans l’industrie : celle des établissements soumis au marché du carbone (SCEQE, 70 % des émissions), dont la tarification effective augmente avec le temps ; et celle des établissements hors SCEQE (30 % des émissions), gelée de 2018 à 2024.En 2019, la tarification effective du CO2 des entreprises les plus émettrices est plus faible (31€/tCO2e) que celle des entreprises les moins émettrices (47€/tCO2e). En 2022, elle est plus élevée (84€/tCO2e contre 60€/tCO2e).L’allocation de quotas gratuits, dont le volume représente, en 2022, 90 % des émissions réalisées par le secteur industriel, abaisse considérablement le poids effectif du marché carbone pour les entreprises qui y sont soumises.Par leur ciblage implicite, les dispositifs fiscaux sans visée environnementale peuvent avoir un effet sur les émissions industrielles totales.En 2019, le niveau de la contribution économique territoriale (les « impôts de production », fortement allégés dans le plan France Relance) est substantiellement plus élevé pour les 10 % des entreprises les plus intenses en CO2 (3 % de la valeur ajoutée), que pour les 10 % les moins intenses (1,2 %). Une suppression de ces impôts bénéficie donc davantage aux entreprises très émettrices

A diagram editor to mechanise categorical proofs

National audienceDiagrammatic proofs are ubiquitous in certain areas of mathematics, especially in category theory. Mechanising such proofs is a tedious task because proof assistants (such as Coq) are text based. We present a prototypical diagram editor to make this process easier, building upon the vscode extension coq-lsp for the Coq proof assistant and a web application available on the author's personal website. It currently targets the UniMath mathematical library for the Coq proof assistant, but could in principle easily be adapted to other targets

β -rays induced displacement damage on epitaxial 4H-SiC revealed by exciton recombination

International audienceOne of the most interesting wide-bandgap semiconductor is 4H-SiC that has an indirect wide-bandgap of 3.3 eV. This material holds great potential to develop power devices that find applications in the field of high-voltage and high-temperature electronics and harsh environments. In this study, we employed complementary noninvasive characterization techniques, including micro-Raman, optical absorption, steady-state, and time-resolved photoluminescence spectroscopy, to investigate the characteristics of a 12 μm thick epitaxial layer of 4H-SiC grown on 4H-SiC. Furthermore, we explored the impact of ionizing radiation on this material, utilizing β-rays and two x-ray sources. The doses are in the range of 1–100 kGy for electrons with energy of 2.5 MeV, 16 kGy for the first x-ray source (an x-ray tube with a W target operating at an anode bias voltage of 28 kV), and 100 kGy for the second x-ray source (an x-ray tube with a W target operating at an anode bias voltage of 100 kV). When exposed to the electron beam, the excitonic band at 3.2 eV exhibits a reduction in its lifetime as the deposited dose increases. In particular, in samples characterized by a greater amount of native defects, both extended and point defects, this effect becomes evident at lower deposited doses. Conversely, in the samples subjected to x-ray irradiation, these effects are not observed. These findings indicate that electron beam irradiation triggers the formation of defects associated with atomic displacement. Ultimately, we have examined the impact of thermal treatments in air, ranging from 100 to 900 °C, to investigate the recovery characteristics of 4H-SiC

Combined search for electroweak production of winos, binos, higgsinos, and sleptons in proton-proton collisions at s\sqrt{s} = 13 TeV

International audienceA combination of the results of several searches for the electroweak production of the supersymmetric partners of standard model bosons, and of charged leptons, is presented. All searches use proton-proton collision data at $\sqrt{s}$ = 13 TeV recorded with the CMS detector at the LHC in 2016-2018. The analyzed data correspond to an integrated luminosity of up to 137 fb$^{-1}$. The results are interpreted in terms of simplified models of supersymmetry. Two new interpretations are added with this combination: a model spectrum with the bino as the lightest supersymmetric particle together with mass-degenerate higgsinos decaying to the bino and a standard model boson, and the compressed-spectrum region of a previously studied model of slepton pair production. Improved analysis techniques are employed to optimize sensitivity for the compressed spectra in the wino and slepton pair production models. The results are consistent with expectations from the standard model. The combination provides a more comprehensive coverage of the model parameter space than the individual searches, extending the exclusion by up to 125 GeV, and also targets some of the intermediate gaps in the mass coverage

Spine for interacting populations and sampling

International audienceWe consider Markov jump processes describing structured populations with interactions via density dependance. We propose a Markov construction with a distinguished individual which allows to describe the random tree and random sample at a given time via a change of probability. This spine construction involves the extension of type space of individuals to include the state of the population. The jump rates outside the spine are also modified. We apply this approach to some issues concerning evolution of populations and competition. For single type populations, we derive the diagram phase of a growth fragmentation model with competition and the growth of the size of birth and death processes with multiple births. We also describe the ancestral lineages of a uniform sample in multitype populations

Puzzle cell shape emerges from the interaction of growth with mechanical constraints

Abstract The puzzle-shaped cells found in the shoot epidermis of many plant species are a fascinating example of complex cell shapes. Because biological form often follows function, the unique shape of these cells suggests that they must serve some adaptive purpose for the plant. We previously proposed that these intricate shapes provide an effective strategy for reducing mechanical stress on the cell wall when epidermal cells undergo growth in more than one direction. Here we analyze a large selection of living and paleo plant species and find that the ability to make puzzle cells is a shared feature across all plant species, although their presence can be hidden as it varies depending on the organ, developmental stage, and environmental conditions. Computational modeling of Arabidopsis and maize epidermal cells revealed that presence and patterning of lobes is a dynamic process that is intricately linked to the growth history and environmental context of the plant organ. Conversely, disrupted lobeyness in mutants or with drug treatments affects plant development and leads to compensatory strategies. We propose that the mechanism underlying the formation of puzzle-shaped cells is likely conserved among higher plants and is a response to a developmental constraint driven by growth and mechanical stress

Comparison of the phase-field approach and cohesive element modeling to analyze the double cleavage drilled compression fracture test of an elastoplastic material: Phase-field approach and cohesive elements for DCDC

International audienceBrittle material Mode I fracture may be characterized by the double cleavage drilled compres- sion test. For linear elastic materials, the critical energy release rate, or fracture toughness, can be estimated simply using the linear elastic fracture mechanics. For other types of constitutive behavior, the material parameter has to be determined with numerical fracture modeling. In this paper, we have used two approaches, the phase-field damage model and the cohesive ele- ments, in order to estimate the critical energy release rate of an elastoplastic material. Firstly, we assessed the numerical models and discussed their parameters by comparison of available data from double cleav- age drilled compression experimental tests run on a sil- ica glass. Both phase-field damage and cohesive zone models were able to reproduce fracture initiation at the observed macroscopic stress for the linear elastic mate- rial. However, the material toughness could not be pre- dicted by the phase-field approach due to the result dependence on the model regularization parameter. Secondly, an elastoplastic methyl methacrylate poly- mer was submitted to the compression test in our lab. Both models were then extended for elastic-perfectly plastic materials. Crack initiation was obtained at the observed macroscopic strain for similar critical energy release rate ranges for both approaches, providing good confidence in the estimated material toughness

Semiring systems arising from hyperrings

Also Preprint arXiv:2207.06739International audienceHyperfields and systems are two algebraic frameworks which have been developed to provide a unified approach to classical and tropical structures. All hyperfields, and more generally hyperrings, can be represented by systems. We show that, conversely, we show that the systems arising in this way, called hypersystems, are characterized by certain elimination axioms. Systems are preserved under standard algebraic constructions; for instance matrices and polynomials over hypersystems are systems, but not hypersystems. We illustrate these results by discussing several examples of systems and hyperfields, and constructions like matroids over systems

Infinite TTˉ\mathrm{T\bar T}-like symmetries of compactified LST

International audienceWe show that the three-dimensional asymptotically linear dilaton background that arises in the near-horizon decoupling region of NS5-branes compactified on $T^4$ admits boundary conditions that lead to an infinite set of symmetries. The associated conserved charges, which implement field-dependent coordinate transformations, are found to be identical to the corresponding generators in a symmetric product orbifold of $T\bar T$ - deformed CFTs. Their algebra is a non-linear modification of the $\mathrm{Virasoro \times Virasoro}$ algebra, which precisely coincides with the algebra of the ``unrescaled'' symmetry generators in $T\bar T$-deformed CFTs. This further strengthens a previously proposed link between the single-trace $T\bar T$ deformation and compactified little string theory