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Can the FCC-hh prove the B-L gauge symmetry?
No full textInternational audienceWe present a phenomenological study of the discovery potential at the FCC-hh for a new heavy neutral vector boson, Z', predicted by the gauge symmetry. Focusing on the parameter space currently not excluded by Large Hadron Collider data, we analyze the dilepton production channel () at a center-of-mass energy of TeV. Full Monte Carlo simulations was performed for different (, ) BSM scenarios and relevant Standard Model backgrounds (including irreducible Drell-Yan, diboson, single top-quark and top-quark pair productions) identifying optimal kinematic and angular selection cuts to guide future searches for this type resonance. We estimate the FCC-hh reach for an integrated luminosity of = 3~. Our results demonstrate that the FCC-hh can exclude Z' masses up to TeV with 95% C.L. for couplings of , and up to TeV for . We find the kinematic and angular cuts that optimize the signal over background ratio and achieve a signal up to Z' masses of TeV. These findings highlight the FCC-hh potential to uncover new physics signals in the high-mass regime
Parity-odd Four-Point Correlation Function from DESI Data Release 1 Luminous Red Galaxy Sample
No full textInternational audienceThe parity-odd four-point function provides a unique probe of fundamental symmetries and potential new physics in the large-scale structure of the Universe. We present measurements of the parity-odd four-point function using the DESI DR1 LRG sample and assess its detection significance. Our analysis considers both auto- and cross-correlations, using two complementary approaches to the covariance: (i) the full analytic covariance matrix applied to the uncompressed data vector, and (ii) a compressed data vector combined with a hybrid covariance matrix constructed from simulations and analytic estimates. When using the full analytic covariance matrix without corrections, we observe apparent auto-correlation signals with significance up to . However, this excess is also consistent with a mismatch between the statistical fluctuations estimated from the simulations and those present in the real data. Our findings therefore suggest that the parity-odd signal in the current DESI DR1 LRG sample is consistent with zero. We note, however, that the low completeness of this sample may have a non-negligible impact on the detection sensitivity. Future data releases with improved completeness will be crucial for further investigation
Measurement of inclusive dijet cross-sections in proton-proton collisions at TeV with the ATLAS detector
No full textInternational audienceInclusive dijet cross-sections have been measured in proton-proton collisions at a centre-of-mass energy of 13 TeV using data with an integrated luminosity of 140 fb, recorded by the ATLAS detector at the Large Hadron Collider during 2015-2018. Jets are identified using the anti- algorithm with a radius parameter of . The inclusive dijet double-differential cross-sections are measured first as a function of the invariant dijet mass and the half absolute rapidity separation between the two leading jets, , , and second as a function of the invariant dijet mass and the total longitudinal boost of the dijet system, , . The measured dijet system covers the invariant mass range from 240 GeV to almost 10 TeV, with dijet separation and dijet boost . The results are unfolded to the particle level and compared with state-of-the-art next-to-next-to-leading-order full colour perturbative QCD calculations, corrected for non-perturbative and electroweak effects
Fermi-LAT detections of novae V1723 Sco and V6598 Sgr
No full textInternational audienceContext. Numerous classical novae have been observed to emit γ-rays (E > 100 MeV) detected by the Fermi-LAT. The prevailing hypothesis attributes this emission to the interaction of accelerated particles within shocks in the nova ejecta. However, the lack of non-thermal X-ray detection coincident with the γ-rays remains a challenge to this theory. Methods. We performed similar analyses of the Fermi-LAT data for both novae to determine the duration, localization, and spectral properties of the γ-ray emission. These results were compared with optical data from the AAVSO database and X-ray observations from NuSTAR, available for V1723 Sco 2024 only, to infer the nature of the accelerated particles. Finally, we used a physical emission model to extract key parameters related to particle acceleration. Results. V1723 Sco 2024 was found to be a very bright γ-ray source with an emission duration of 15 days allowing us to constrain the spectral index and the total energy of accelerated protons. Despite early NuSTAR observations, no non-thermal X-ray emission was detected simultaneously with the γ-rays. However, unexpected γ-ray and thermal hard X-ray emission were observed more than 40 days after the nova outburst, suggesting that particle acceleration can occur even several weeks post-eruption. V6598 Sgr 2023, on the other hand, was detected by the Fermi-LAT at a significance level of 4σover just two days, one of the shortest γ-ray emission durations ever recorded, coinciding with a rapid decline in optical brightness. Finally, the high ratio of γ-ray to optical luminosities and γ-ray to X-ray luminosities for both novae, as well as the curvature of the γ-ray spectrum of V1723 Sco below 500 MeV, are all more consistent with the hadronic than the leptonic scenario for γ-ray generation in novae
Symplectic mechanics of relativistic spinning compact bodies. III. quadratic-in-spin integrability in Type-D Einstein spacetimes: persistence and breakdown
No full textInternational audienceWe develop a covariant Hamiltonian formulation of the Mathisson-Papapetrou-Tulczyjew-Dixon dynamics at quadratic order in spin under the Tulczyjew-Dixon spin supplementary condition (TD SSC). In four-dimensional, type-D Einstein (vacuum/-vacuum) spacetimes admitting a non-degenerate Killing-Yano (KY) tensor, we reduce via a Dirac bracket to the 10-dimensional physical phase space and model the quadratic sector with a spin-induced quadrupole characterized by a deformability ( for black-hole--like; for material or exotic compact objects). For , we construct five independent first integrals -- an autonomous Hamiltonian, two KY-generated Killing invariants, a linear Rüdiger constant, and a quadratic Carter-Rüdiger constant -- establishing Liouville-Arnold integrability at quadratic order in spin. For , the symmetry-generated invariants are not conserved in general and integrability does not persist at this order. The proof proceeds via covariant Poisson-bracket computations using a null bivector decomposition; Kerr is recovered as a special case. These results show that integrability can persist beyond Kerr and beyond the linear-in-spin regime, laying groundwork for symmetry-based, beyond-Kerr modelling of asymmetric-mass, spinning compact binaries
The Binary Fraction of Stars in the Dwarf Galaxy Ursa Minor via Dark Energy Spectroscopic Instrument
No full textInternational audienceWe utilize multi-epoch line-of-sight velocity measurements from the Milky Way Survey of the Dark Energy Spectroscopic Instrument to estimate the binary fraction for member stars in the dwarf spheroidal galaxy Ursa Minor. Our dataset comprises 670 distinct member stars, with a total of more than 2,000 observations collected over approximately one year. We constrain the binary fraction for UMi to be and , with the binary orbital parameter distributions based on solar neighborhood observation from Duquennoy & Mayor (1991) and Moe & Di Stefano (2017), respectively. Furthermore, by dividing our data into two subsamples at the median metallicity, we identify that the binary fraction for the metal-rich ([Fe/H]>-2.14) population is slightly higher than that of the metal-poor ([Fe/H]<-2.14) population. Based on the Moe & Di Stefano model, the best-constrained binary fractions for metal-rich and metal-poor populations in UMi are and , respectively. After a thorough examination, we find that this offset cannot be attributed to sample selection effects. We also divide our data into two subsamples according to their projected radius to the center of UMi, and find that the more centrally concentrated population in a denser environment has a lower binary fraction of , compared with for the subsample in more outskirts
Probing neutron star interiors and the properties of cold ultra-dense matter with the SKAO
No full textInternational audienceMatter inside neutron stars is compressed to densities several times greater than nuclear saturation density, while maintaining low temperatures and large asymmetries between neutrons and protons. Neutron stars, therefore, provide a unique laboratory for testing physics in environments that cannot be recreated on Earth. To uncover the highly uncertain nature of cold, ultra-dense matter, discovering and monitoring pulsars is essential, and the SKA will play a crucial role in this endeavour. In this paper, we will present the current state-of-the-art in dense matter physics and dense matter superfluidity, and discuss recent advances in measuring global neutron star properties (masses, moments of inertia, and maximum rotation frequencies) as well as non-global observables (pulsar glitches and free precession). We will specifically highlight how radio observations of isolated neutron stars and those in binaries -- such as those performed with the SKA in the near future -- inform our understanding of ultra-dense physics and address in detail how SKAO's telescopes unprecedented sensitivity, large-scale survey and sub-arraying capabilities will enable novel dense matter constraints. We will also address the potential impact of dark matter and modified gravity models on these constraints and emphasise the role of synergies between the SKA and other facilities, specifically X-ray telescopes and next-generation gravitational wave observatories
Constraints on the polarization angle oscillations of the Crab Nebula with the Simons Array and its applications to the search for axion-like particles
No full textInternational audienceWe present a search for polarization oscillation of the Crab Nebula, also known as Tau A, at millimeter wavelengths using observations with the Simons Array, the successor experiment to POLARBEAR. We follow up on previous work by POLARBEAR using 90 GHz band data of the 2023 observing season of the Simons Array to evaluate the variability of Tau A's polarization angle. Tau A is widely used as a polarization angle calibration source in millimeter-wave astronomy, and thus it is necessary to validate the stability. Additionally, an interesting application of the time-resolved polarimetry of Tau A is to search for axion-like particles (ALPs). We do not detect a global signal across the frequencies considered in this analysis and place a median 95% upper bound of polarization oscillation amplitude over oscillation frequencies from 3.39 year to 1.50 day. This constrains the ALP-photon coupling at a median 95% upper bound of in the mass range from to eV, assuming the ALP constitutes all of dark matter, its field is a stochastic Gaussian field, and it is the sole source of Tau A's polarization angle oscillation. Additionally, we do not detect signal at the frequencies where 2.5 hints were previously reported by POLARBEAR, but we do not exclude these signals at the 95% confidence level
The Lazuli Space Observatory: Architecture & Capabilities
No full textInternational audienceThe Lazuli Space Observatory is a 3-meter aperture astronomical facility designed for rapid-response observations and precision astrophysics across visible to near-infrared wavelengths (400-1700 nm bandpass). An off-axis, freeform telescope delivers diffraction-limited image quality (Strehl 0.8 at 633 nm) to three instruments across a wide, flat focal plane. The three instruments provide complementary capabilities: a Wide-field Context Camera (WCC) delivers multi-band imaging over a 35' 12' footprint with high-cadence photometry; an Integral Field Spectrograph (IFS) provides continuous 400-1700 nm spectroscopy at R 100-500 for stable spectrophotometry; and an ExtraSolar Coronagraph (ESC) enables high-contrast imaging expected to reach raw contrasts of and post-processed contrasts approaching . Operating from a 3:1 lunar-resonant orbit, Lazuli will respond to targets of opportunity in under four hours--a programmatic requirement designed to enable routine temporal responsiveness that is unprecedented for a space telescope of this size. Lazuli's technical capabilities are shaped around three broad science areas: (1) time-domain and multi-messenger astronomy, (2) stars and planets, and (3) cosmology. These capabilities enable a potent mix of science spanning gravitational wave counterpart characterization, fast-evolving transients, Type Ia supernova cosmology, high-contrast exoplanet imaging, and spectroscopy of exoplanet atmospheres. While these areas guide the observatory design, Lazuli is conceived as a general-purpose facility capable of supporting a wide range of astrophysical investigations, with open time for the global community. We describe the observatory architecture and capabilities in the preliminary design phase, with science operations anticipated following a rapid development cycle from concept to launch
Commissioning of proANUBIS: A proof-of-concept detector for the ANUBIS experiment
No full textInternational audienceLong-lived particles (LLPs), predicted by various extensions of the Standard Model (SM), have become a key focus of the contemporary search programme for physics beyond the SM. To enhance LLP discovery potential at the LHC, the ANUBIS experiment has been proposed to instrument the ceiling of the ATLAS experiment's underground cavern with dedicated tracking detectors. This report summarises recent progress towards realising ANUBIS. Specifically, a key milestone has been achieved with the installation and commissioning of proANUBIS, a prototype that serves as a proof-of-concept for ANUBIS. We describe the proANUBIS setup, including its remotely-operated data acquisition system and automatic signal processing chain. The proANUBIS demonstrator is used to evaluate the detector performance under realistic conditions in the UX1 ATLAS experimental cavern, including readout synchronisation with the ATLAS experiment. Furthermore, proANUBIS allows for the direct measurement of relevant background processes in a representative location within the ATLAS cavern, providing input for the simulation of such processes for the future ANUBIS detector. The paper concludes with an update on the current status of the ANUBIS project and its roadmap toward a full-scale implementation in the ATLAS cavern