HAL Clermont Université
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Measurement of asymmetries in decays
No full textInternational audienceA search for violation in and decays is presented using the full Run 1 and Run 2 data samples of collisions collected with the LHCb detector, corresponding to an integrated luminosity of 9 at center-of-mass energies of 7, 8, and 13 TeV. For the Run 2 data sample, the -violating asymmetries are measured to be and , where the first uncertainty is statistical and the second is systematic. Following significant improvements in the evaluation of systematic uncertainties compared to the previous LHCb measurement, the Run 1 dataset is reanalyzed to update the corresponding results. When combining the Run 2 and updated Run 1 measurements, the final results are found to be and , constituting the most precise measurements of these asymmetries to date
Measurement of CP asymmetry in decays
No full textInternational audienceA measurement of the CP-violating parameters in BsDsK decays is reported, based on the analysis of proton-proton collision data corresponding to an integrated luminosity of at a centre-of-mass energy of . The measured parameters are , , , and , where the first uncertainty is statistical and the second systematic. Together with the value of the Bs mixing phase , these parameters are used to obtain a measurement of the CKM angle equal to modulo , where the uncertainty contains both statistical and systematic contributions. This result is combined with the previous LHCb measurement in this channel using resulting in a determination of
Eruptive dynamics of open-vent andesitic volcanoes retrieved from petrological and componentry analysis of recent explosive phases (2021-2022) of Sangay (Ecuador)
No full textco-auteur étrangerInternational audienceSince its reawakening in 2019, Sangay volcano (Ecuador) experienced a continuous, low magnitude eruptive activity that was disrupted by some mild-explosive pulses. Andean communities in central Ecuador and the Guayaquil International Airport have been affected by the ash fallouts. Through componentry, geochemical and petrological analysis, we studied ash and lapilli samples, emitted during the mild-explosive eruptions of 2020–2021 and during the minor eruptions of 2022, to document the changes in eruptive dynamics, constrain the pre-eruptive physical conditions, and identify the potential triggering mechanisms. Major elements whole-rock compositions show a progressive decrease in silica content, from andesitic to basaltic andesitic compositions, and a concomitant increase in magnesium content over time. Componentry, textures and chemical variations in groundmass glass support the idea that Sangay's shallow plumbing system hosts magmas that have evolved in composition, having variable physical properties that control the eruptive dynamics. The change in eruptive style towards more explosive dynamics in 2020–2021 was probably associated with the feeding of a more mafic and gas-rich magma from deep. The consequence, reflected in the groundmass glass chemistry and componentry data, is the “excavation” of the partially crystallized magma stalling in the conduits, which led to the observation of the more diverse compositions in the juvenile material. This work contributes to a better understanding of the eruptive behavior of long-lived, open-vent andesitic volcanoes, and to explore the link between eruptive dynamics and the petrological evolution of magmas
The importance of mass balance in life cycle assessment of nature-based solutions for wastewater treatment: key learning points from a case study
No full textInternational audienceThis study aims to perform a comprehensive life cycle assessment (LCA) of nature-based solutions (NBS) for wastewater treatment (WWT), specifically focusing on a French vertical flow (VF) wetland. The LCA encompasses the construction phase, operational phase, and end-of-life management, with a particular emphasis on achieving a balanced mass flow for carbon, nitrogen, and phosphorus across air, water, and soil compartments. The VF wetland is evaluated for its environmental impacts and compared to a conventional activated sludge system. The key findings reveal that the VF wetland achieves substantial reductions in resource use, yet requires significantly more land and exhibits higher impacts on greenhouse gas emissions and in categories sensitive to water emissions. The results underline the importance of complete mass balances in LCAs of NBS to accurately identify environmental hotspots. Recommendations for methodological improvements and system boundary definitions are provided to enhance the definition of mass balance within NBS
Study of Λ0 b and Ξ0 b decays to Λh+h ′− and evidence for CP violation in Λ0 b → ΛK+K− decays
No full textInternational audienceA study of Λ 0 b and Ξ0 b decays to Λh+h ′− (h (′) = π, K) is performed using pp collision data collected by the LHCb experiment during LHC Runs 1–2, corresponding to an integrated luminosity of 9 fb−1 . The branching fractions for these decays are measured using the Λ 0 b → Λ + c (→ Λπ+)π − decay as control channel. The decays Λ 0 b → Λπ+π − and Ξ0 b → ΛK−π + are observed for the first time. For decay modes with sufficient signal yields, CP asymmetries are measured in the full and localized regions of the final-state phase space. Evidence is found for CP violation in the Λ 0 b → ΛK+K− decay, interpreted as originating primarily from an asymmetric Λ 0 b → N∗+K− decay amplitude. The measured CP asymmetries for the other decays are compatible with zero
Des voix souterraines qui font du bruit: La poésie underground des régimes communistes peut-elle devenir world literature ?
No full textInternational audienceAlors que la survie de la poésie underground des régimes communistes repose sur une existence clandestine et étouffée, nombre de ces voix souterraines décident de résonner dans le monde entier au prisme de traductions en langues mondialisantes. Dès lors, cet article se propose d’interroger l’insertion de la poésie underground dans la world literature, en comparant l’œuvre de cinq poètes : Egon Bondy en Tchécoslovaquie, Nguyễn Chí Thiện au Viêt Nam, Reinaldo Arenas à Cuba, Guo Lusheng 郭路生 en Chine et Bandi 반디 en Corée du Nord. En plus d’emprunter des voies de circulation similaires, l’œuvre de ces poètes semble partager des motifs que nous nous proposons de faire émerger à partir d’une étude comparative
The Deep Latent Position Block Model For The Block Clustering And Latent Representation Of Networks
No full textInternational audienceThe increased quantity of data has led to a soaring use of networks to model relationships between different objects, represented as nodes. Since the number of nodes can be particularly large, the network information must be summarised through node clustering methods. In order to make the results interpretable, a relevant visualisation of the network is also required. To tackle both issues, we propose a new methodology called deep latent position block model (Deep LPBM) which simultaneously provides a network visualisation coherent with block modelling, allowing a clustering more general than community detection methods, as well as a continuous representation of nodes in a latent space given by partial membership vectors. Our methodology is based on a variational autoencoder strategy, relying on a graph convolutional network, with a specifically designed decoder. The inference is done using both variational and stochastic approximations. In order to efficiently select the number of clusters, we provide a comparison of three model selection criteria. An extensive benchmark as well as an evaluation of the partial memberships are provided. We conclude with an analysis of a French political blogosphere network and a comparison with another methodology to illustrate the insights provided by Deep LPBM results
Measurement of meson production in pp collisions at = 13 TeV
No full textInternational audienceThe -differential cross section of meson production in pp collisions at = 13 TeV at midrapidity () was measured with the ALICE detector at the LHC, covering an unprecedented transverse-momentum range of GeV/. The meson is reconstructed via the decay channel. The results are compared with various theoretical calculations: PYTHIA8.2 with the Monash 2013 tune overestimates the data by up to 50%, whereas good agreement is observed with Next-to-Leading Order (NLO) calculations incorporating fragmentation using a broken SU(3) model. The ratio is presented and compared with theoretical calculations and the available measurements at lower collision energies. The presented data triples the ranges of previously available measurements. A constant ratio of is found above a transverse momentum of 4 GeV/, which is in agreement with previous findings at lower collision energies within the systematic and statistical uncertainties
Identifying Quasars from the DESI Bright Galaxy Survey
No full textInternational audienceThe Dark Energy Spectroscopic Instrument (DESI) cosmology survey includes a Bright Galaxy Survey (BGS) which will yield spectra for over ten million bright galaxies (r2 which are either faint quasars with nearby projected companions or very bright quasars with strong absorption features including the Lyman-apha forest, metal absorbers and/or broad absorption lines
Phototrophy improves the aerial fitness in a photoheterotrophic Methylobacterium isolated from clouds
No full textSurface ecosystems such as the phyllosphere host diverse microbial communities, a fraction of54 which may detach and remain aloft for up to several days. As airborne, bacteria are challenged by high55 exposure to oxidants and limited nutrients, and we postulate that specific biological trait such as56 phototrophy may support the maintenance of metabolic functions. Omics data reanalysis indicates the57presence of the genetic biomarker of anoxygenic photosynthesis in the atmosphere and clouds. Using58 an atmospheric simulation chamber, we monitored proxies for viability and metabolic activity in59 airborne photoheterotrophic aerobic Methylobacterium sp. cells expressing or not photosynthetic60 capabilities (bacteriochlorophyll). We observe shorter airborne residence time in [Bchl+] cells than in61 [Bchl-] cells, and higher survival rate and potential for metabolic activity, in particular under light62 exposure. These results imply that aerial transport is not neutral, and can favor the maintenance and63 spread of biological traits often considered elsewhere as poorly competitiv