HAL-Polytechnique
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First determination of the spin-parity of baryons
No full textInternational audienceThe decay chains are observed, and the spin-parity of baryons is determined for the first time. The measurement is performed using proton-proton collision data at a center-of-mass energy of , corresponding to an integrated luminosity of , recorded by the~ experiment between 2016 and 2018. The spin-parity of the baryons is determined to be with a significance of more than () compared to all other tested hypotheses. The up-down asymmetries of the transitions are measured to be (), consistent with maximal parity violation, where the first uncertainty is statistical and the second is systematic. These results support the hypothesis that the baryons correspond to the first -wave -mode excitation of the flavor triplet
Supervised Contamination Detection, with Flow Cytometry Application
No full textInternational audienceThe contamination detection problem aims to determine whether a set of observations has been contaminated, i.e. whether it contains points drawn from a distribution different from the reference distribution. Here, we consider a supervised problem, where labeled samples drawn from both the reference distribution and the contamination distribution are available at training time. This problem is motivated by the detection of rare cells in flow cytometry. Compared to novelty detection problems or two-sample testing, where only samples from the reference distribution are available, the challenge lies in efficiently leveraging the observations from the contamination detection to design more powerful tests. In this article, we introduce a test for the supervised contamination detection problem. We provide non-asymptotic guarantees on its Type I error, and characterize its detection rate. The test relies on estimating reference and contamination densities using histograms, and its power depends strongly on the choice of the corresponding partition. We present an algorithm for judiciously choosing the partition that results in a powerful test. Simulations illustrate the good empirical performances of our partition selection algorithm and the efficiency of our test. Finally, we showcase our method and apply it to a real flow cytometry dataset
Stairway to discovery: a report on the CMS programme of cross section measurements from millibarns to femtobarns
No full textInternational audienceThe Large Hadron Collider at CERN, delivering proton-proton collisions at much higher energies and far higher luminosities than previous machines, has enabled a comprehensive programme of measurements of the standard model (SM) processes by the CMS experiment. These unprecedented capabilities facilitate precise measurements of the properties of a wide array of processes, the most fundamental being cross sections. The discovery of the Higgs boson and the measurement of its mass became the keystone of the SM. Knowledge of the mass of the Higgs boson allows precision comparisons of the predictions of the SM with the corresponding measurements. These measurements span the range from one of the most copious SM processes, the total inelastic cross section for proton-proton interactions, to the rarest ones, such as Higgs boson pair production. They cover the production of Higgs bosons, top quarks, single and multibosons, and hadronic jets. Associated parameters, such as coupling constants, are also measured. These cross section measurements can be pictured as a descending stairway, on which the lowest steps represent the rarest processes allowed by the SM, some never seen before
Long time behavior of a degenerate stochastic system modeling the response of a population face to environmental impacts
No full textInternational audienceWe study the asymptotics of a two-dimensional stochastic differential system with a degenerate diffusion matrix. This system describes the dynamics of a population where individuals contribute to the degradation of their environment through two different behaviors. We exploit the almost one-dimensional form of the dynamical system to compute explicitly the Freidlin-Wentzell action functional. That allows to give conditions under which the small noise regime of the invariant measure is concentrated around the equilibrium of the dynamical system having the smallest diffusion coefficient
Review of top quark mass measurements in CMS
No full textInternational audienceThe top quark mass is one of the most intriguing parameters of the standard model (SM). Its value indicates a Yukawa coupling close to unity, and the resulting strong ties to the Higgs physics make the top quark mass a crucial ingredient for understanding essential aspects of the electroweak sector of the SM. While it is such an important parameter of the SM, its measurement and interpretation in terms of the Lagrangian parameter are challenging. The CMS Collaboration has performed multiple measurements of the top quark mass, addressing these challenges from different angles: highly precise `direct' measurements, using the top quark decay products, as well as `indirect' measurements aiming at accurate interpretations in terms of the Lagrangian parameter. Recent mass measurements using Lorentz-boosted top quarks are particularly promising, opening a new avenue of measurements based on top quark decay products contained in a single particle jet, with superior prospects for accurate theoretical interpretations. Moreover, dedicated studies of the dominant uncertainties in the modelling of the signal processes have been performed. This review offers the first comprehensive overview of these measurements performed by the CMS Collaboration using the data collected at centre-of-mass energies of 7, 8, and 13 TeV
Fermi-detection of -ray Emissions from the Hot Coronae of Radio-quiet Active Galactic Nuclei
No full textInternational audienceRelativistic jets around supermassive black holes (SMBHs) are well-known powerful -ray emitters. In absence of the jets in radio-quiet active galactic nuclei (AGNs), how the SMBHs work in -ray bands is still unknown despite of great observational efforts made in the last 3 decades. Considering the previous efforts, we carefully select an AGN sample composed of 37 nearby Seyfert galaxies with ultra-hard X-rays for the goals of -ray detections by excluding all potential contamination in this band. Adopting a stacking technique, here we report the significant -ray detection (, or ) from the sample using 15-year Fermi-Large Area Telescope (LAT) observation. We find an average -ray luminosity of the sample as at energies from 1-300 GeV. Limited by the well-known pair production from the interaction of -rays with low energy photons, several GeV -rays are found to originate from an extended corona (), whereas the canonical much more compact X-ray corona () is responsible for 1 to several GeV -rays. The finding of the compact region lends to strong supports to the long-time theoretical expectations, but the extended corona is beyond all the existing models. One promising scenario is that the electron-positron pairs produced in the compact X-ray corona would expand as fireball, similar to that in -ray bursts, forming the structure of extended corona
Intense and localized export of selected marine snow types at eddy edges in the South Atlantic Ocean
No full textInternational audienceAbstract. The biological carbon pump (BCP) comprises a wide variety of processes involved in transferring organic carbon from the surface to the deep ocean. This results in long-term carbon sequestration. Without the BCP, atmospheric CO2 concentrations would be around 200 ppm higher. This study reveals that ocean dynamics at the mesoscale and submesoscale could have a major impact on particulate organic matter (POM) vertical distribution. Our results indicate that intense submesoscale frontal regions, such as those between mesoscale eddies, could lead to an important accumulation and transport of POM from the mixed-layer depth (MLD) down to the mesopelagic zone. To reach these conclusions, a multifaceted approach was applied. It included in situ measurements and marine snow images from a BGC-Argo float equipped with an Underwater Vision Profiler (UVP6), satellite altimetry data, and Lagrangian diagnostics. We focused our study on three intense features in marine snow distribution, observed during the 17-month-long float mission in the Cape Basin in the southwest of Africa. These features were located in the frontal region between mesoscale eddies. Our study suggests that a particle injection pump induced by a frontogenesis-driven mechanism has the potential to enhance the effectiveness of the biological pump by increasing the depth at which carbon is injected into the water column. This work also emphasizes the importance of establishing repeated sampling campaigns targeting the interface zones between eddies. This could improve our understanding of the mechanisms involved in the deep accumulation of marine snow observed at eddy interfaces
Repurposing chlorpromazine for anti-leukaemic therapy with the drug-in-cyclodextrin-in-liposome nanocarrier platform
No full textInternational audienceAcute myeloid leukaemia (AML) accounts for 30 % of adult leukaemia cases, predominantly affecting individuals over 60. The standard “7 + 3” intensive chemotherapy regimen is unsuitable for many elderly patients, contributing to AML's poor prognosis. While progress in drug therapies has been made, breakthroughs remain limited, indication-specific, and slow to expand. Drug repurposing offers a faster route to therapy development, while nanocarrier encapsulation broadens the scope of viable drug candidates.Chlorpromazine (CPZ) is an antipsychotic which has been identified as a potential anti-leukaemic agent. Due to its ability to cross the blood-brain barrier, it is likely to cause central nervous system (CNS) effects. The drug-in-cyclodextrin-in-liposome (DCL) nanocarrier platform enables the formulation of CPZ encapsulated with cyclodextrins (CDs) such as HP-γ-CD, SBE-β-CD, and Sugammadex.The CD/CPZ formulations were equally, or more efficient than free CPZ in inducing AML cell death. Uptake of the DCL in AML cells quickly reached saturation, with minimal differences among formulations, except for SBE-β-CD. When injected intravenously in zebrafish larvae, the different DCLs did not differ in biodistribution, and no brain accumulation was observed at two days post-injection. These DCL-based CPZ formulations maintain anti-leukaemic activity, avoid CNS accumulation, and allow drug availability adjustments based on the included CD
The Volterra Stein-Stein model with stochastic interest rates
No full textWe introduce the Volterra Stein-Stein model with stochastic interest rates, where both volatility and interest rates are driven by correlated Gaussian Volterra processes. This framework unifies various wellknown Markovian and non-Markovian models while preserving analytical tractability for pricing and hedging financial derivatives. We derive explicit formulas for pricing zero-coupon bond and interest rate cap or floor, along with a semi-explicit expression for the characteristic function of the log-forward index using Fredholm resolvents and determinants. This allows for fast and efficient derivative pricing and calibration via Fourier methods. We calibrate our model to market data and observe that our framework is flexible enough to capture key empirical features, such as the humped-shaped term structure of ATM implied volatilities for cap options and the concave ATM implied volatility skew term structure (in loglog scale) of the S&P 500 options. Finally, we establish connections between our characteristic function formula and expressions that depend on infinite-dimensional Riccati equations, thereby making the link with conventional linear-quadratic models.</div
Computation of classical and -adic -series of -motives
No full textInternational audienceWe design an algorithm for computing the -series associated to an Anderson -motives, exhibiting quasilinear complexity with respect to the target precision. Based on experiments, we conjecture that the order of vanishing at of the -adic -series of a given Anderson -motive with good reduction does not depend on the finite place