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Illuminating Scalar Dark Matter Co-Scattering in EFT with Monophoton Signatures
No full textInternational audienceWe investigate the co-scattering mechanism for dark matter production in an EFT framework which contains new -odd singlets, namely two fermions and a real scalar . The singlet scalar is the dark matter candidate. The dimension-5 operators play a vital role to set the observed DM relic density. We focus on a nearly degenerate mass spectrum for the odd particles to allow for a significant contribution from the co-scattering or co-annihilation mechanisms. We present two benchmark points where either of the two mechanisms primarily set the DM relic abundance. The main constraint on the model at the LHC arise from the ATLAS mono- search. We obtain the parameter space allowed by the observed relic density and the mono- search after performing a scan over the key parameters, the masses and couplings . We find the region of parameter space where the relic abundance is set primarily by the co-scattering mechanism while being allowed by the LHC search. We also determine how the model can be further probed at the HL-LHC via the mono- signature
Energy correlators in four-dimensional gravity
No full textInternational audienceWe investigate energy correlators in four-dimensional gravitational theories, which provide a simple class of infrared-finite observables. We compute the one- and two-point energy correlators at one loop in supergravity and in pure Einstein gravity, with particular emphasis on the contact terms arising from the interplay between virtual corrections and real emissions. We explicitly demonstrate the cancellation of infrared divergences and verify the Ward identities associated with energy-momentum conservation. In the back-to-back limit, we derive an all-order expression for the energy-energy correlator, showing that it is governed by universal soft-graviton dynamics. We further introduce a particularly simple beam-averaged energy-energy correlator and compute it in different gravitational theories, including tree-level string theory. The resulting correlators exhibit analyticity and polynomial boundedness, allowing for the formulation of dispersion relations, which we explore. Finally, we discuss additional singularities of the gravitational energy correlators, absent in QCD, that originate from the long-range nature of the gravitational interactions
Thermal modelling of the discharge of a 180 kW·h latent thermal energy storage demonstrator
No full textInternational audienceThis paper presents the validation of a numerical model against experimental data for the discharge of a latent thermal energy storage. The experimental data come from the experimental characterization of 180 kW·h phase change material storage demonstrator installed in a substation of the Grenoble district heating network. The heat transfer fluid used is water and the phase change material is RT70HC. The numerical model has been presented and validated for different charging cases in a previous paper. This paper focus on the modelling of the phase-change during discharges, as the RT70HC has two solidification peaks. The model is a 1.5D model, developed in the DYMOLA software, with a 1D homogeneous approach for the heat transfer fluid combined with a 1.5D approach for the phase change material. The model with two solidification peaks reproduces the total energy unloaded during a discharge with an accuracy of 98.3 %, a root-mean-square error of 3 kW on outlet power and 1.6 °C for storage outlet temperature. These results are slightly better than a model with one peak of solidification (accuracy of 98 %, root-mean-square error of 3.22 kW on outlet power and 1.7 °C for storage outlet temperature). The conclusion is that consideration of the two peaks in this case is not mandatory
Slug flow boiling in microchannels at high vapour volume fraction
No full textInternational audienceIn this work, we experimentally study the thermal performance and bubbly flow characteristicsof convective boiling inside a multi-microchannel exchanger operated in slug flow regime at highvapour volume fraction with CO2 as the working fluid. To that purpose, flow regime and heattransfer are characterised for a silicon/pyrex heat exchanger containing 16 parallel microchannelsof hydraulic diameter 183 μm, for saturation temperatures close to −35◦C, mass fluxes between258 kg/(m2s) and 537 kg/(m2s), heat fluxes range 12.7 − 69 kW/m2 and inlet vapour volumefraction ranging from 68% up to 85%. The investigated boiling flow is characterised by a laminarregime, a high confinement, a small Capillary number (Ca < 0.036) and a Jakob number rangeof 0.1 ≤ Ja ≤ 1. At high vapour volume fraction, the heat transfer is found to be monitored bythe heat transport in the liquid film forms between bubbles and the wall because the contact timewith bubbles (and liquid film) is much larger than the contact time with liquid slugs. In addition,since at wall the film velocity vanishes because of adherence, experimental Nusselt numbers arefound to be close to the one predicted by the pure heat conduction problem in the liquid film. Thisbehaviour explains why the experimental heat transfer coefficient is systematically degraded whenthe flow velocity and the liquid film thickness increase together. This study represents the firstmeasurement of heat transfer coefficients for CO2 boiling flow below −30◦C and for an hydraulicdiameter below 200 μm. Such a silicon exchanger design can be useful for the direct cooling ofCMOS sensors at negative temperatures without thermal interface between the refrigerant and thesubstrate
Cosmic-ray cooling by dark matter in astrophysical jets
No full textInternational audienceAstrophysical jets from powerful active galactic nuclei (AGN) have recently been proposed as promising probes of dark matter (DM) in the sub-GeV mass range. AGN launch relativistic jets that accelerate cosmic rays (CRs) to very high energies, which can then interact with their surroundings and produce multiwavelength (MW) emission spanning from radio frequencies to TeV rays. If DM consists of light particles, their interactions with CRs could lead to an additional cooling mechanism that modifies the expected MW emission. In this work, we analyse the MW spectrum of Markarian 421, a well-studied AGN, using a multizone leptonic jet model that includes the interactions between CR electrons and DM particles. For the first time, we account for the uncertainties in the astrophysical jet dynamics, which have been previously neglected when constraining the CR-DM interactions. By fitting simultaneously jet parameters and DM-electrons interactions, we use the MW data from Markarian 421 to set constraints on the DM-induced CR cooling. We obtain 5 upper limit for a DM mass of . We demonstrate that this is about a factor of five weaker than traditional approaches, implying that properly accounting for degeneracies between jet dynamics and DM interactions is key to derive robust constraints on DM interactions
Validity and reliability of the French version of the quick-FAAM (Q-FAAM-F) among patients undergoing anatomic ankle ligament reconstruction
No full textInternational audiencePurpose: To evaluate the validity and reliability of the French version of the Quick Foot and Ankle Ability Measure (Q-FAAM-F) in French-speaking patients with chronic lateral ankle instability (CLAI).Methods: We conducted a prospective observational cohort in a sports surgery centre with repeated assessments preoperatively, and at 3 and 6 months postoperatively; the primary analysis was cross-sectional at 6 months. Consecutive CLAI patients undergoing anatomic lateral ankle ligament reconstruction (AALR) were included. Patients completed the Q-FAAM-F (12 items derived from the validated French FAAM) alongside the full FAAM, FAOS, ALR-RSI, CAIT and VAS-pain. Internal consistency (Cronbach's α), item-total and inter-item correlations, and construct validity (Pearson's r) were calculated. Discriminant validity used ROC analyses for CLAI status (CAIT < 24) and return to sport (RTS), defined on the RTS continuum as return to the pre-injury sport at any level at 6 months and treated as an external clinical variable.Results: Among 275 patients (56% male; median age 32 years), Q-FAAM-F showed excellent internal consistency (α = 0.96) and strong item-total correlations (mean r ≈ 0.65). Convergent validity was strong with the FAAM (r = 0.95) and with FAOS and ALR-RSI; divergent validity was supported by the absence of correlation with CAIT of the nonoperated limb. ROC AUC for CLAI status and RTS were high; optimal cut-offs were 78.1/100 (CLAI: sensitivity 81.3%, specificity 85.4%) and 80.2/100 (RTS: sensitivity 75.4%, specificity 87.9%). Conclusion: The Q-FAAM-F is a valid and reliable PROM for French-speaking CLAI patients, suitable for clinical practice and research. Precise AUC-based thresholds may support clinical decision-making at 6 months
Geodynamo Simulation Explorer: a filterable and visualisable catalogue to explore geodynamo simulations
No full textWe present a new web tool, Geodynamo Simulation Explorer, to survey available published simulations of rapidly rotating spherical dynamos.With numerical codes and computers being increasingly efficient, recent years have seen a surge in the number of publications presenting such computations.Our tool comes as an interactive catalogue that allows exploring existing dynamos with respect to input and output dimensionless parameters, choosing from various dynamo setups (e.g. choice of boundary conditions, couplings at play, etc.), with the possibility to test scaling laws on a filtered set of simulations. It also links each dynamo to its associated publication and possibly to online datasets.Thought of as a collaborative and scalable initiative, the web interface allows uploading new simulation metadata.The whole interface, displayed as a website, is designed for the community to have a better overview while driving transparency, open-source initiatives, and FAIR principles (Findable, Accessible, Interoperable, Reusable).Check it out and feed it at https://geodyn.univ-grenoble-alpes.fr/explorer/
Global convergence in wood evolution is driven by drought on continents and frost-free temperatures on islands
No full textPhylogenetically derived woodiness (DW), the evolutionary reversion from herbaceousness to woodiness in angiosperms, is one of the most conspicuous characteristics of (sub)tropical island floras. Here, we show that DW across continents is more common than previously thought, especially in frost-free and open habitats with pronounced seasonal drought. Using a novel dataset on the evolution of woodiness in angiosperms, we discovered substantially more derived woody species (DWS) and independent evolutionary transitions on continents compared to islands (4,808 species and 513 transitions vs. 1,084 and 175, respectively). However, we identified more insular DWS hotspots (22) than the four continental DWS hotspots: the Andes, Southern Africa, the Old-World Dry Belt and Australia. A structural equation model controlling for total species richness suggests that aridity is the strongest predictor of the number of DWS on continents, while frost-free temperatures best predict DWS on islands. Precipitation seasonality and mean elevation emerge as additional significant predictors in both cases, with a further potential role for light-prone open habitats. In summary, the diverse global drivers behind the hundreds of independent woodiness shifts highlight the existence of various mechanisms that lead to increased wood formation in stems, confirming its adaptive value over evolutionary time
Hierarchical summaries for primordial non-Gaussianities
No full textInternational audienceThe advent of Stage IV galaxy redshift surveys such as DESI and Euclid marks the beginning of an era of precision cosmology, with one key objective being the detection of primordial non-Gaussianities (PNG), potential signatures of inflationary physics. In particular, constraining the amplitude of local-type PNG, parameterised by , with , would provide a critical test of single versus multi-field inflation scenarios. While current large-scale structure and cosmic microwave background analyses have achieved -, further improvements demand novel data compression strategies. We propose a hybrid estimator that hierarchically combines standard -point and -point statistics with a field-level neural summary, motivated by recent theoretical work that shows that such a combination is nearly optimal, disentangling primordial from late-time non-Gaussianity. We employ PatchNet, a convolutional neural network that extracts small-scale information from sub-volumes (patches) of the halo number density field while large-scale information is retained via the power spectrum and bispectrum. Using Quijote-PNG simulations, we evaluate the Fisher information of this combined estimator across various redshifts, halo mass cuts, and scale cuts. Our results demonstrate that the inclusion of patch-based field-level compression always enhances constraints on , reaching gains of - at low (), and capturing information beyond the bispectrum. This approach offers a computationally efficient and scalable pathway to tighten the PNG constraints from forthcoming survey data