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No theoretical basis for an orbit–spin coupling inertial force in planetary atmospheres
No full textInternational audienceCorrelations between Martian orbital dynamics and the interannual variability of global dust storms (GDS) were reported by Shirley (2015) and Shirley and Mischna (2017). To explain this correlation, Shirley (2017) proposed a theoretical derivation of an inertial force acting on the Martian atmosphere, depending on both the planet's spin rate and its orbital angular momentum. This term, referred to as the ''coupling term acceleration'' (CTA), has been hypothesized to provide a dynamical forcing mechanism for GDS initiation. In this study, we revisit the orbit-spin coupling hypothesis by re-deriving the inertial forces acting on a parcel of air in the atmosphere of a rotating, orbiting planet. We show that no orbit-spin coupling term naturally appears in the equations of motion. Furthermore, the inertial accelerations associated with the planet's orbital motion are almost entirely compensated by the external gravitational field, leaving only a well-known gravitational tidal term. This result demonstrates that there is no theoretical basis for a direct orbit-spin coupling force acting on planetary atmospheres
Search for heavy scalar resonances decaying to Lorentz-boosted Higgs and Higgs-like bosons in the 4q final state at = 13 TeV
No full textInternational audienceA search is performed for a heavy scalar resonance X decaying to a Higgs boson (H) and a Higgs-like scalar boson (Y) in the two bottom quark (H ) and four quark (Y VV 4q) final state, where V denotes a W or Z boson. Masses of the X between 900 and 4000 GeV and the Y between 60 and 2800 GeV are considered. The search is performed in data collected by the CMS experiment at the CERN LHC from proton-proton collisions at 13 TeV center-of-mass energy, with a data set corresponding to a total integrated luminosity of 138 fb. It targets the Lorentz-boosted regime, in which the products of the H decay can be reconstructed as a single large-area jet, and those from the Y VV 4q decay as either one Y 4q or two V to jets. Jet identification and mass reconstruction exploit machine-learning tools, including a novel attention-based "particle transformer" for Y 4q identification. No significant excess is observed in the data above the standard model background expectation. Upper limits on the product of production cross section and branching fraction as low as 0.2 fb are derived at 95% confidence level for various mass hypotheses. This is the first search at the LHC for scalar resonances in the all-hadronic VV decay channel
A zero-test for D-algebraic transseries
No full textConsider formal power series f_1, ..., f_k ∈ ℚ [[z]] that are defined as the solutions of a system of polynomial differential equations together with a sufficient number of initial conditions. Given P ∈ ℚ[F_1, ..., F_k], several algorithms have been proposed in order to test whether P(f_1, ..., f_k) = 0. In this paper, we present such an algorithm for the case where f_1, ..., f_k are so-called transseries instead of power series.</div
Predictability of North Pacific blocking events: Analogue‐based analysis of historical MIROC6 simulations
No full textInternational audienceAtmospheric blocking exerts a profound influence on midlatitude circulation, yet its predictability remains elusive, due to intrinsic nonlinearities and sensitivity to initial conditions. While blocking dynamics have been extensively studied, the impact of geographical positioning on predictability remains largely unexplored. This study provides a comparative assessment of the predictability of western and eastern North Pacific blocking events, leveraging analogue‐based diagnostics applied to Coupled Model Intercomparison Project Phase 6 (CMIP6) Model for Interdisciplinary Research on Climate, version 6 (MIROC6) simulations. Blocking structures are identified using geopotential height gradient reversal, with their temporal evolution analyzed through trajectory tracking and error growth metrics. Results reveal that eastern blocks exhibit lower predictability, characterized by rapid error divergence and increased mean logarithmic growth rates compared with western blocks. Persistence analysis gives no significant difference between eastern and western North Pacific blocking events. Sensitivity analyses across varying detection thresholds validate the robustness of these findings
Un modèle de population d'arbres structurée par des traits phénologiques
No full textIn the context of global warming, tree populations rely on two primary mechanisms of adaptation: phenotypic plasticity, which enables individuals to adjust their behavior in response to environmental stress, and genetic evolution, driven by natural selection and genetic diversity within the population. Understanding the interplay between these mechanisms is crucial for assessing the impacts of climate change on forest ecosystems and for informing sustainable management strategies. In this manuscript, we focus on a specific phenological adaptation: the ability of trees to enter summer dormancy once a critical temperature threshold is exceeded. Individuals are characterized by this threshold temperature and by their seed production capacity. We first establish a detailed mathematical model describing the population dynamics under these traits, and progressively reduce it to a system of two coupled ordinary differential equations. This simpler macroscopic model is then analyzed numerically, to investigate how the population reacts to a shift in its environment: an temperature increase, a drop in precipitation levels, or a combination of the two. Our results highlight contrasting effects of water stress and temperature stress on population dynamics, as well as the ambivalent effect of the plasticity
Long-time behaviour of a multidimensional age-dependent branching process with a singular jump kernel modelling telomere shortening
No full textInternational audienceIn this article, we investigate the ergodic behaviour of a multidimensional age-dependent branching process with a singular jump kernel, motivated by studying the phenomenon of telomere shortening in cell populations. Our model tracks individuals evolving within a continuous-time framework indexed by a binary tree, characterised by age and a multidimensional trait. Branching events occur with rates dependent on age, where offspring inherit traits from their parent with random increase or decrease in some coordinates, while the most of them are left unchanged. Exponential ergodicity is obtained at the cost of an exponential normalisation, despite the fact that we have an unbounded age-dependent birth rate that may depend on the multidimensional trait, and a non-compact transition kernel. These two difficulties are respectively treated by stochastically comparing our model to Bellman-Harris processes, and by using a weak form of a Harnack inequality. We conclude this study by giving examples where the assumptions of our main result are verified
Ordering-Independent Wheeler-DeWitt Equation for Flat Minisuperspace Models
No full textInternational audienceWe consider minisuperspace models with quadratic kinetic terms, assuming a flat target space and a closed Universe. We show that, upon canonical quantization of the Hamiltonian, only a restricted subset of operator orderings is consistent with the path-integral viewpoint. Remarkably, all consistent orderings are physically equivalent to all orders in . Specifically, each choice of path-integral measure in the definition of the wavefunction path integral uniquely determines an operator ordering and hence a corresponding Wheeler-DeWitt equation. The consistent orderings are in one-to-one correspondence with the Jacobians associated with all field redefinitions of a set of canonical degrees of freedom. For each admissible operator ordering--or equivalently, each path-integral measure--we identify a definite, positive Hilbert-space inner product. All such prescriptions define the same quantum theory, in the sense that they lead to identical physical observables. We illustrate our formalism by applying it to de Sitter Jackiw-Teitelboim gravity and to the Starobinsky model
Perturbative results for the matrix elements of the vector current and the role of different infrared regulators
No full textInternational audienceWe investigate the twist-2 unpolarized generalized parton distributions (GPDs) of quarks for an on-shell gluon target in quantum chromodynamics. These GPDs parametrize the leading-twist matrix elements of the nonlocal light-like flavor-singlet vector current. We compute them at one-loop accuracy in perturbation theory using a quark mass and dimensional regularization as infrared regulators. In particular, we discuss the limit of vanishing momentum transfer. The present work extends our previous related study on the axial current
High-level hadronic tau lepton triggers of the CMS experiment in proton-proton collisions at = 13.6 TeV
No full textInternational audienceThe trigger system of the CMS detector is pivotal in the acquisition of data for physics measurements and searches. Studies of final states characterized by hadronic decays of tau leptons require the reconstruction and the identification of genuine tau leptons against quark- and gluon-initiated jets at the trigger level. This is a difficult task, particularly as improvements to the LHC have resulted in an increased number of interactions per bunch crossing in recent years. To address this challenge, a series of machine-learning algorithms with high identification efficiency and low computational cost have been incorporated into the high-level trigger for hadronically decaying tau leptons. In this paper, these developments and the trigger performance are summarized using data collected by the CMS experiment in proton-proton collisions at = 13.6 TeV in 20222023, corresponding to an integrated luminosity of 62 fb
Measurement of B meson production fraction ratios in proton-proton collisions at = 13 TeV using open-charm and charmonium decays
No full textInternational audienceProduction fraction ratios of B, B, and B mesons are measured in proton-proton collisions at = 13 TeV using a special data set recorded in 2018 with high-rate triggers designed to collect an unbiased sample of b hadrons with the CMS experiment at the LHC. These data allow the use of the open-charm decays of B mesons (BD) where the D meson decays into fully hadronic final states. Production fraction ratios as functions of B meson transverse momentum () and rapidity () are measured using the open-charm decays in the kinematic range of 8 60 GeV and 2.25. In addition, the same data are used to measure the relative production fraction ratios with the charmonium decay channels (B XJ/ with X indicating a K, K(892), or (1020) meson) with the J/ meson decaying into a pair of muons. By utilizing known branching fractions, precision theoretical calculations, and the open-charm results, the production fraction ratios in the charmonium samples are determined with an absolute normalization for the first time. These results also improve several world-average values of the ratios of branching fractions of B meson decays to charmonium and open-charm states. Finally, we test isospin invariance in B meson production in proton-proton collisions and observe that it holds within the experimental precision