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No evidence for anisotropy from Tully-Fisher or supernova distances
No full textInternational audienceClaims of anisotropy in the Hubble constant have been made based on direct distance tracers such as Tully-Fisher galaxies and Type Ia supernovae. We revisit these using the CosmicFlows-4 Tully-Fisher W1 subsample, 2MTF and SFI++ Tully-Fisher catalogues, and the Pantheon+ supernova compilation (restricted to ), including a dipole in either the Tully-Fisher zero-point or the standardised supernova absolute magnitude. Our forward-modelling framework jointly calibrates the distance relation, marginalises over distances, and accounts for peculiar velocities using a linear-theory reconstruction. We compare the anisotropic and isotropic model using the Bayesian evidence. In the CosmicFlows-4 sample, we infer a zero-point dipole of amplitude mag, or per cent when expressed as a dipole in the Hubble parameter. This is consistent with previous estimates but at higher significance: model comparison yields odds of in favour of including the zero-point dipole. In Pantheon+ we infer zero-point dipole amplitude of mag, or per cent when expressed as a dipole in the Hubble parameter. However, by allowing for a radially varying velocity dipole, we show that the anisotropic model captures local flow features (or possibly systematics) in the data rather than an actual linearly growing effective bulk flow caused by anisotropy in the zero-point or expansion rate. Inferring a more general bulk flow curve we find results fully consistent with expectations from the standard cosmological model
Species Quantum Mechanics
No full textInternational audienceIn this note we introduce some concepts of Species Quantum Mechanics. Specifically, we consider quantum operators that correspond to the species number and the tower mass scale in the context of the swampland distance conjecture. We discuss the commutation relations, a possible wave function, and symplectic duality transformations on the conjugate variables. Furthermore, we argue that the Castellano-Ruiz-Valenzuela (CRV) pattern is a consequence of the canonical commutation rules of moduli space quantum mechanics. We also connect the canonical quantization to the periods of Calabi-Yau compactifications to explore other aspects of the CRV pattern, including its possible connection to the Ooguri-Vafa-Verlinde black hole quantization procedure
A 3D segmented Water-based Liquid Scintillator for high-precision detection of neutrinos in water
No full textInternational audiencePrecision detection of neutrino-nucleus interactions in water with the complete detection of the final state, including leptons and hadrons, is challenging due to water being a non-scintillating medium. This can be a limitation for the next-generation long-baseline neutrino oscillation experiments, such as Hyper-Kamiokande, where the neutrino-nucleus interaction models must reach a few percent-level accuracy. Water-based liquid scintillator can be a game changer for the future near detectors. In this article, we propose a novel design consisting of a 3D highly-segmented water-based liquid scintillator. The water-based liquid scintillator is encapsulated within a highly-segmented rigid but very light structure that provides the optical isolation with a 1 cm granularity, each read out by orthogonal wavelength shifting fibers, and 81% of water by mass in the active volume. Such configuration is also suitable for pure liquid scintillator. The detector design, prototyped and validated with cosmic ray data, is described and results are reported. The optical model is studied with Monte Carlo simulations and results are compared with the collected data
The BAO-CMB Tension and Implications for Inflation
No full textInternational audienceThe scalar spectral index is a powerful test of inflationary models. The tightest constraint on to date derives from the combination of cosmic microwave background (CMB) data with baryon acoustic oscillation (BAO) data. The resulting constraint is shifted significantly upward relative to the constraint from CMB alone, with the consequence that previously preferred inflationary models are seemingly disfavored by . Here we show that this shift in is the combined effect of a degeneracy between and BAO parameters exhibited by CMB data and the tension between CMB datasets and DESI BAO data under the assumption of the standard cosmological model. Given the crucial role of in discriminating between inflationary models, we urge caution in interpreting CMB+BAO constraints on until the BAO-CMB tension is resolved
Measurement of the branching fraction of the decay and isospin asymmetry of decays
No full textInternational audienceThis paper describes a measurement of the \LbJpsiLambda branching fraction using data collected with the LHCb experiment in proton-proton collisions from 2016 to 2018. The dataset corresponds to an integrated luminosity of 5.4\invfb. The branching fraction is determined relative to that of decays, yielding , where the first uncertainty is statistical, the second systematic, the third due to external inputs on branching fractions and the fourth due to the ratio of baryon and meson hadronisation fractions. In addition, the isospin asymmetry between the rates of and decays is measured to be , where the first uncertainty is statistical and the second systematic
Search for heavy neutral leptons in decays of W bosons produced in 13 TeV collisions using prompt signatures in the ATLAS detector
No full textInternational audienceThe existence of right-handed neutrinos with Majorana masses below the electroweak scale could help address the origins of neutrino masses, the matter-antimatter asymmetry, and dark matter. In this paper, leptonic decays of W bosons from 140 fb of 13 TeV proton-proton collisions at the LHC, reconstructed in the ATLAS experiment, are used to search for heavy neutral leptons produced through their mixing with muon or electron neutrinos in a scenario with lepton number violation. The search is conducted using prompt leptonic decay signatures. The considered final states require two same-charge leptons or three leptons, while vetoing three-lepton same-flavour topologies. No significant excess over the expected Standard Model backgrounds is found, leading to constraints on the heavy neutral lepton's mixing with muon and electron neutrinos for heavy-neutral-lepton masses. The analysis excludes values above and values above in the full mass range of 8-65 GeV. The strongest constraints are placed on heavy-neutral-lepton masses in the range 15--30 GeV of and
Gamma rays as leptonic portals to energetic neutrinos: a new Monte Carlo approach
No full textInternational audienceHigh center-of-mass electromagnetic~(EM) interactions could produce decaying heavy leptons and hadrons, leading to neutrino generation. These processes might occur in the most extreme astrophysical scenarios, potentially altering the expected gamma-ray and neutrino fluxes in both the hadronic and the leptonic pictures. For instance, neutrinos could arise from high-redshift EM cascades, triggered by gamma rays beyond scattering background photons, from radio to ultraviolet energy bands. Such energetic gamma rays are predicted in cosmogenic models and in scenarios involving non-standard physics. On astrophysical scales, leptonic production of neutrinos could take place in active galactic nuclei cores, where several-TeV gamma rays interact with the X-ray photons from the hot corona. We explore these scenarios within the CRPropa Monte Carlo code framework, developing dedicated tools to account for leptonic production and decay of heavy leptons and hadrons. In particular, the latter are performed by interfacing with the PYTHIA event generator. With these novel tools, we characterise the spectrum and flavour composition of neutrinos emerging from cosmological EM cascades and from leptonic processes in the core of active galactic nuclei. Finally, we investigate the leptonic production of neutrinos in the context of the IceCube detection of NGC~1068
Bigraded Castelnuovo-Mumford regularity and Groebner bases
No full textInternational audienceWe study the relation between the bigraded Castelnuovo-Mumford regularity of abihomogeneous ideal in the coordinate ring of the product of two projective spaces and the bidegrees of a Groebner basis of with respect to the degree reverse lexicographical monomial order in generic coordinates. For the single-graded case, Bayer and Stillman unraveled all aspects of this relationship forty years ago and these results led to complexity estimates for computations with Groebner bases. We build on this work to introduce a bounding region of the bidegrees of minimal generators of bihomogeneous Groebner bases for . We also use this region to certify the presence of some minimalgenerators close to its boundary. Finally, we show that, up to a certain shift, this region is related to the bigraded Castelnuovo-Mumford regularity of
Evidence for the collective nature of radial flow in Pb+Pb collisions with the ATLAS detector
No full textInternational audienceAnisotropic flow and radial flow are two key probes of the expansion dynamics and properties of the quark-gluon plasma (QGP). While anisotropic flow has been extensively studied, radial flow, which governs the system's radial expansion, has received less attention. Notably, experimental evidence for the global and collective nature of radial flow has been lacking. This Letter presents the first measurement of transverse momentum () dependence of radial flow fluctuations () over GeV, using a two-particle correlation method in Pb+Pb collisions at TeV. The data reveal three key features supporting the collective nature of radial flow: long-range correlation in pseudorapidity, factorization in , and centrality-independent shape in . The comparison with a hydrodynamic model demonstrates the sensitivity of to bulk viscosity, a crucial transport property of the QGP. These findings establish a new, powerful tool for probing collective dynamics and properties of the QGP
Euclid Quick Data Release (Q1). First detections from the galaxy cluster workflow
No full textInternational audienceThe first survey data release by the Euclid mission covers approximately in the Euclid Deep Fields to the same depth as the Euclid Wide Survey. This paper showcases, for the first time, the performance of cluster finders on Euclid data and presents examples of validated clusters in the Quick Release 1 (Q1) imaging data. We identify clusters using two algorithms (AMICO and PZWav) implemented in the Euclid cluster-detection pipeline. We explore the internal consistency of detections from the two codes, and cross-match detections with known clusters from other surveys using external multi-wavelength and spectroscopic data sets. This enables assessment of the Euclid photometric redshift accuracy and also of systematics such as mis-centring between the optical cluster centre and centres based on X-ray and/or Sunyaev--Zeldovich observations. We report 426 joint PZWav and AMICO-detected clusters with high signal-to-noise ratios over the full Q1 area in the redshift range . The chosen redshift and signal-to-noise thresholds are motivated by the photometric quality of the early Euclid data. We provide richness estimates for each of the Euclid-detected clusters and show its correlation with various external cluster mass proxies. Out of the full sample, 77 systems are potentially new to the literature. Overall, the Q1 cluster catalogue demonstrates a successful validation of the workflow ahead of the Euclid Data Release 1, based on the consistency of internal and external properties of Euclid-detected clusters