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Milankovitch forcing of equilibrium ground-ice on Mars
No full textInternational audienceExchangeable ice deposits are present today on the surface of Mars in polar caps and in the shallow subsurface in mid-latitudes. Geologic observations indicate these deposits waxed and waned in the past, at times, along with the emplacement and loss of equatorial glaciers. Here, we couple a climate model with an ice stability criterion, to self-consistently determine the distribution of the mid-latitude ground-ice deposits in di!usive equilibrium with the atmosphere, at present and under past orbital configurations. This new coupling and iteration between the short-term and long-term models improves upon past calculations that do not allow the ice table to evolve over timescales much longer than the annual climate dynamics. The model predictions for the extent of the equilibrium ice-table in the past match the latitudinal distribution of terrain softening geologic features previously mapped. At past times, thermally stable shallow ground ice is expected even in equatorial regions, in parts of Tharsis and Arabia Terra.</div
Graph Transformers for Query Plan Representation: Potentials and Challenges
No full textInternational audienceQuery Plan Representation (QPR) is central to workload modeling, with various deep-learning based architectures proposed in the literature. Our work is motivated by two key observations: (i)~the research community still lacks clarity on which model, if any, best suits the QPR problem; and (ii) while transformers have revolutionized many fields, their potential for QPR remains largely underexplored. This study examines the strengths and challenges of Graph Transformers for QPR. We introduce a new taxonomy that unifies deep-learning based QPR techniques along key design axes. Our benchmark analysis of common QPR architectures reveals that Graph Transformer Networks (GTNs) consistently outperform alternatives, but can degrade under limited training data. To address this, we propose novel data augmentation techniques to enhance training diversity and refine GTN architectures by replacing ineffective language-model-inspired components with techniques better suited for query plans. Evaluation on JOB, TPC-H, and TPC-DS benchmarks shows that with sufficient training data, enhanced GTNs outperform existing models for capturing complex queries (JOB Full and TPC-DS) and enable the query embedder trained on TPC-DS to generalize to TPC-H queries out of the box
Observation of decays
No full textInternational audienceSearches are presented for decays, where is a charmed meson and is a charged pion or kaon, using collision data collected by the LHCb experiment corresponding to an integrated luminosity of . The decays , and are observed for the first time. Their branching fractions, expressed as ratios relative to that of the decay, are determined to be \begin{align*} \mathcal{R}(B_c^+\to D^+ K^+π^-) =(1.96 \pm 0.23\pm 0.08 \pm 0.10)\times 10^{-3},&\\ \mathcal{R}(B_c^+\to D^{*+} K^+π^-) =(3.67 \pm 0.55 \pm 0.24\pm 0.20)\times 10^{-3},&\\ \mathcal{R}(B_c^+\to D_s^+ K^+ K^-) =(1.61 \pm 0.35\pm 0.13\pm 0.07)\times 10^{-3}, \end{align*} where the first uncertainty is statistical, the second is systematic, and the third is due to the limited precision on the -meson branching fractions. The decay channels proceed primarily through excited or resonances or mesons, and open a new avenue for studies of charge-parity violation in beauty mesons
From Thermodynamic Criticality to Geometric Criticality: A Linear Kernel Map from Matter Susceptibilities to Black-Hole Shadows
No full textInternational audienceWe construct an explicit linear map from compact, conserved thermodynamic/effective-medium perturbations of the stress-energy tensor to the metric response in static, spherically symmetric spacetimes, and from there to geometric observables of direct relevance to horizon-scale imaging: the shadow radius and photon-sphere frequency. The response is expressed through -bounded kernels written in a piecewise "local tail" form, which makes transparent the separation between near-photon-sphere sensitivity and far-zone contributions (including AdS tails). Under mild assumptions on the matter susceptibilities near a critical point, dominated convergence transfers the thermodynamic exponent to the geometric susceptibility, , with controlled analytic corrections. We further provide AdS far-zone bounds with explicit outside-support constants depending only on background geometric data at the photon sphere and shell geometry. A reproducible numerical pipeline with convergence diagnostics is presented and benchmarked
Water Vapor Vertical Distribution on Mars After Six Yearsof TGO/NOMAD Solar Occultations: 2. Cross‐ValidationWithin TGO and Comparison With MPCM
No full textInternational audienceThis is the second part of an investigation of water vapor in the Martian atmosphere using solar occultation observations by the spectrometer NOMAD on board the ExoMars Trace Gas Orbiter. Following the analysis performed in the first part, hereafter named as Paper I, a cross-validation exercise between NOMAD and ACS results is presented, showing global as well as profile-by-profile comparisons. The results reveal an overall good agreement between different teams and instruments, taking into account the different retrieval methodologies. In order to compare with model predictions, we perform an exhaustive analysis of the water vapor simulated by Mars Planetary Climate Model (MPCM). It shows that the MPCM reproduces most of the water vapor climatological features observed in the atmosphere. However, several discrepancies between model and observations are noticed. Some of these are possibly related to the vertical distribution of dust and its effect on the global circulation and on the water vapor vertical transport. Other data-model differences found at 60 km seem to be related to discrepancies on the water ice cloud formation in the MPCM. In addition, we include a cluster analysis of Martian water vapor vertical profiles for the first time. This technique applied to MPCM and NOMAD water vapor retrievals reveal distinct groups of profiles being representative of specific seasons and latitudinal regions, similarly distributed in both model and observations. Moreover, it allows us to provide a simplified water vapor climatology, useful to detect out-of-season events and biases in the retrieval processes
Proving the existence of localized patterns and saddle node bifurcations in 1D activator-inhibitor type models
No full textIn this paper, we present a general framework for constructively proving the existence and stability of stationary localized 1D solutions and saddle-node bifurcations in activatorinhibitor systems using computer-assisted proofs. Specifically, we develop the necessary analysis to compute explicit upper bounds required in a Newton-Kantorovich approach. Given an approximate solution ū, this approach relies on establishing that a well-chosen fixed point map is contracting on a neighborhood ū. For this matter, we construct an approximate inverse of the linearization around ū, and establish sufficient conditions under which the contraction is achieved. This provides a framework for which computer-assisted analysis can be applied to verify the existence and local uniqueness of solutions in a vicinity of ū, and control the linearization around ū. Furthermore, we extend the method to rigorously establish saddle-node bifurcations of localized solutions for the same type of models, by considering a well-chosen zero-finding problem. This depends on the rigorous control of the spectrum of the linearization around the bifurcation point. Finally, we demonstrate the effectiveness of the framework by proving the existence and stability of multiple steady-state patterns in various activatorinhibitor systems, as well as a saddle-node bifurcation in the Glycolysis model.</div
Measurement of Polarization in the Reaction at GeV/ toward a New Scattering Experiment
No full textInternational audienceThis paper presents high-precision experimental data of the polarization of the hyperon in the reaction, measured in the angular range with a fine bin width of . The data were obtained from the J-PARC E40 experiment at the K1.8 beamline in the J-PARC Hadron Experimental Facility. The observed average polarization of in the range was , demonstrating the successful extraction of precise polarization observables. This result provides essential experimental input for partial wave analysis (PWA) of dynamical coupled-channel (DCC) models, which aim to uncover the underlying mechanisms of resonances that emerge in intermediate states of and interactions. Besides, it indicates the feasibility of a strongly polarized beam suitable for future scattering experiments (e.g., J-PARC E86)
Time-dependent Neural Galerkin Method for Quantum Dynamics
No full textInternational audienceWe introduce a classical computational method for quantum dynamics that relies on a global-in-time variational principle. Unlike conventional time-stepping approaches, our scheme computes the entire state trajectory over a finite time window by minimizing a loss function that enforces the Schrödinger's equation. The variational state is parametrized with a Galerkin-inspired ansatz based on a time-dependent linear combination of time-independent Neural Quantum States. This structure is particularly well-suited for exploring long-time dynamics and enables bounding the error with the exact evolution via the global loss function. We showcase the method by simulating global quantum quenches in the paradigmatic Transverse-Field Ising model in both 1D and 2D, uncovering signatures of ergodicity breaking and absence of thermalization in two dimensions. Overall, our method is competitive compared to state-of-the-art time-dependent variational approaches, while unlocking previously inaccessible dynamical regimes of strongly interacting quantum systems
First exclusive reconstruction of the B, B, and B mesons and precise measurement of their masses
No full textInternational audienceUsing proton-proton collision data collected by the CMS experiment at = 13 TeV in 20162018, corresponding to an integrated luminosity of 140 fb, the first full reconstruction of the three vector B meson states, B, B, and B, is performed. The mass differences between the excited mesons and their corresponding ground states are measured to be = 45.277 0.039 0.027 MeV, = 45.471 0.056 0.028 MeV, and = 49.407 0.132 0.041 MeV, where the first uncertainties are statistical and the second are systematic. These results improve on the precision of previous measurements by an order of magnitude
Observation of (1S) + Z associated production and measurement of the effective double-parton scattering cross section in proton-proton collisions at = 13 TeV
No full textInternational audienceThe observation of associated production of an (1S) meson with a Z boson and a measurement of the ratio of its fiducial cross section to the fiducial cross section of the Z boson are presented. Both the (1S) meson and the Z boson are identified via decays into a pair of opposite-sign muons. The analysis is based on proton-proton (pp) collision data at = 13 TeV, collected with the CMS detector in 20162018 and corresponding to an integrated luminosity of 138 fb. Using the production of the Z boson decaying into four muons as a normalization channel, the ratio of the fiducial cross sections (pp Z (1S))(Z )((1S) ) to (pp Z)(Z 4) is measured to be = (21.1 55 (stat) 0.6 (syst) 10), where stat and syst denote the statistical and systematic uncertainties, respectively. The result is used to extract the effective double-parton scattering cross section = 13.0. In addition, for the first time, is measured in bins of the transverse momentum of the (1S) meson or of the Z boson