UV completions of scalar-tensor EFTs

International audienceWe study models that give rise to scalar-tensor effective field theories (EFTs) at low energies. Our framework involves massive particles of spin $S=0, 1/2, 1$ coupled to gravity and to a real massless scalar in the UV. Integrating out the massive states leads to a scalar-tensor EFT describing the massless graviton and scalar degrees of freedom. Using the on-shell amplitude methods and the spinor-helicity formalism, we match the two frameworks at one loop, so as to express the EFT Wilson coefficients in terms of the UV masses and coupling. We explore the space of the operators generated in the EFT, including the ones related to the scalar Gauss-Bonnet (SGB) and dynamical Chern-Simons (DCS) gravity theories. We demonstrate that, within our setup, the SGB interactions are always generated with shift-symmetry breaking operators. This is in contrast to the DCS case, where there is a unique choice that preserves the shift symmetry in the IR, corresponding to a theory of spin 1/2 fermions and a complex scalar with a Peccei-Quinn global symmetry

Measuring short-range correlations and quasi-elastic cross sections in A(e,e') at x>1 and modest Q2^2

International audienceWe present results from the Jefferson Lab E08-014 experiment, investigating short-range correlations (SRC) through measurements of absolute inclusive quasi-elastic cross sections and their ratios. This study utilized 3.356 GeV electrons scattered off targets including $^2$H, $^3$He, $^4$He, $^{12}$C, $^{40}$Ca, and $^{48}$Ca, at modest momentum transfers ($1.3 2$) did not yield a clear plateau; instead, the data diverged from the predicted 3N-SRC behavior as momentum transfer increased. However, when analyzed in terms of the struck nucleon's light-cone momentum, the data exhibited the opposite trend, progressively approaching the predicted 3N-SRC plateau. These observations suggest that future measurements at higher energies may facilitate a definitive isolation and identification of 3N-SRCs

Ultra-sensitive radon assay using an electrostatic chamber in a recirculating system

International audienceRare event searches such as neutrinoless double beta decay and Weakly Interacting Massive Particle detection require ultra-low background detectors. Radon contamination is a significant challenge for these experiments, which employ highly sensitive radon assay techniques to identify and select low-emission materials. This work presents the development of ultra-sensitive electrostatic chamber (ESC) instruments designed to measure radon emanation in a recirculating gas loop, for future lower background experiments. Unlike traditional methods that separate emanation and detection steps, this system allows continuous radon transport and detection. This is made possible with a custom-built recirculation pump. A Python-based analysis framework, PyDAn, was developed to process and fit time-dependent radon decay data. Radon emanation rates are given for various materials measured with this instrument. A radon source of known activity provides an absolute calibration, enabling statistically-limited minimal detectable activities of 20 $\mu$Bq. These devices are powerful tools for screening materials in the development of low-background particle physics experiments

Measurement of solar neutrino interaction rate below 3.49 MeV in Super-Kamiokande-IV

International audienceSuper-Kamiokande has observed $^{8}\text{B}$ solar neutrino elastic scattering at recoil electron kinetic energies ($E_{kin}$) as low as 3.49 MeV to study neutrino flavor conversion within the sun. At SK-observable energies, these conversions are dominated by the Mikheyev-Smirnov-Wolfenstein effect. An upturn in the electron neutrino survival probability in which vacuum neutrino oscillations become dominant is predicted to occur at lower energies, but radioactive background increases exponentially with decreasing energy. New machine learning approaches provide substantial background reduction below 3.49 MeV such that statistical extraction of solar neutrino interactions becomes feasible. This article presents an analysis of the solar neutrino interaction rate at $E_{kin}$ < 3.49 MeV with the full SK-IV period, using data from a wideband intelligent trigger when available and with a boosted decision tree for event selection. A solar neutrino signal is observed between 2.99 MeV < $E_{kin}$ < 3.49 MeV with $2.76σ$ significance and a data to unoscillated MC ratio of $0.307^{+0.112}_{-0.111}$. This additional low energy data has a negligible effect on the $1σ$ intervals of the fits to the solar neutrino energy spectrum but has a noticeable effect on the best fit when using the exponential parameterization

Measurements of the proton-induced reaction 155Gd(p,n)155Tb at energies between 7 and 26 MeV with highly-enriched 155Gd targets

International audienceBackground The need for new medical radionuclides continues to grow as treatments become more personalised. Terbium-155, a gamma emitter, is an appealing isotope that could be used for Single Photon Emission Computed Tomography (SPECT). Since it belongs to the Terbium quadruplet, it could be coupled with other Tb isotopes to form a theranostic pair. However, it is currently not accessible in sufficient quantities with an acceptable radionuclidic purity. An investigation of the excitation function of the nuclear reaction 155Gd(p,n) over an energy range accessible to most medical cyclotrons is relevant for optimizing 155Tb production. For the first time, we report the measurements of this reaction with highly enriched (&gt; 99.0%) 155Gd targets. Methods Pure 155Gd targets, with isotopic enrichment better than 99%, have been produced using the highperformance electromagnetic separator SIDONIE at IJClab, Orsay, France. Proton activation measurements have been performed using two different cyclotrons and a linear accelerator (linac). Results The full excitation function of 155Gd(p,n)155Tb has been obtained over the 7-26 MeV range. All 18 measured cross-sections are consistent with each other, without the need of any renormalization. All the obtained data were compared with already published results and clearly show a maximum production at 11 MeV, with a cross section of 500 mb. Conclusion Experimental data indicates excitation function maximum around 11 MeV for the studied energy range, and cross sections are greater when target purity in 155Gd is higher

Constraints on Solar Reflected Dark Matter from a combined analysis of XENON1T and XENONnT data

International audienceWe report on a search for sub-GeV dark matter upscattered via the solar reflection mechanism in the heavy mediator scenario. Under the Standard Halo Model, keV to MeV dark matter produces nuclear recoils with energies below the detection threshold of liquid xenon time projection chambers. We enhance sensitivity to low-mass dark matter by considering dark matter-electron scattering, employing dedicated event selections to reduce the detection threshold, and exploiting the additional kinetic energy imparted to the dark matter particle by solar upscattering. Using XENON1T ionization-only and XENONnT low-energy electronic recoil datasets, we exclude previously unconstrained DM-electron scattering cross section for masses between $4.6\, \text{keV/}c^2$ and $20\, \text{keV/}c^2$, and between $0.2\, \text{MeV/}c^2$ and $2\, \text{MeV/}c^2$, reaching a minimum of $3.41\times10^{-39}\, \text{cm}^2$ for a mass of $0.3\, \text{MeV/}c^2$ at 90% confidence level

Search for charged Higgs bosons decaying into top and bottom quarks in lepton+jets final states in proton-proton collisions at s\sqrt{s} = 13 TeV

International audienceA search is presented for charged Higgs bosons (H$^\pm$) in proton-proton (pp) collision events via the pp $\to$ (b)H$^\pm$ processes, with H$^\pm$ decaying into top (t) and bottom (b) quarks. The search targets final states with one lepton, missing transverse momentum, and two or more b jets. The analysis is based on data collected at a center-of-mass energy of 13 TeV with the CMS detector at the LHC, corresponding to an integrated luminosity of 138 fb$^{-1}$. We search for charged Higgs bosons in the 200 GeV to 1 TeV mass range. The results are interpreted within the generalized two-Higgs-doublet model (g2HDM). This model predicts additional Yukawa couplings of the Higgs bosons to the top quark $ρ_\mathrm{tt}$, the top and charm quark $ρ_\mathrm{tc}$, and the top and up quark $ρ_\mathrm{tu}$. This search focuses on the real components of $ρ_\mathrm{tt}$ and $ρ_\mathrm{tc}$, which are probed up to values of unity. An excess is observed with respect to the standard model expectation with a local significance of 2.4 standard deviations for a signal with an H$^\pm$ boson mass ($m_{\mathrm{H}^\pm}$) of 600 GeV. Limits are derived on the product of the cross section $σ$(pp $\to$ (b)H$^\pm$) and branching fraction $\mathcal{B}$(H$^\pm$$\to$ tb, t $\to$ b$\ellν$), where $\ell$ = e, $μ$. The values of $ρ_\mathrm{tc} \gtrsim$ 0.15$-$0.5 are excluded at 95% confidence level, depending on the $m_{\mathrm{H}^\pm}$ and $ρ_\mathrm{tt}$ assumptions. The results represent the first search for charged Higgs bosons within the g2HDM framework and complement the existing results on additional neutral Higgs bosons

Measurements of quasar proximity zones with the Lyman-αα forest of DESI Y1 quasars

International audienceThe intergalactic medium (IGM) around quasars is shaped by their dense environments and by their excess ionizing radiation, forming a "quasar proximity zone" whose size and anisotropy depend on the quasar's halo mass, luminosity, age, and radiation geometry. Using over 10,000 quasar pairs from the Dark Energy Spectroscopic Instrument (DESI) Year 1 data, with projected comoving separations $r_{\perp} < 2\,h^{-1}{\rm Mpc}$, we investigate how the proximity zone of foreground quasars at $z\sim2{\rm-}3.5$ affects Lyman-alpha absorption in their background quasars. The large DESI sample enables unprecedented precision in measuring this "transverse proximity" effect, allowing a detailed investigation of the signal's dependence on the projected separation of quasar pairs and the luminosity of the foreground quasar. We find that enhanced gas clustering near quasars dominates over their ionizing effect, leading to stronger absorption on neighboring sightlines. Under the assumption that quasar ionizing luminosity is isotropic and steady, we infer the IGM overdensity profile in the vicinity of quasars, finding overdensities as high as $Δ\sim 10$ at comoving distance $\sim 1\,h^{-1}{\rm Mpc}$ from the most luminous systems. Surprisingly, however, we find no significant dependence of the proximity profile on the luminosity of the foreground quasar. This lack of luminosity dependence could reflect a cancellation between higher ionizing flux and higher gas overdensity, or it could indicate that quasar emission is highly time variable or anisotropic, so that the observed luminosity does not trace the ionizing flux on nearby sightlines

Optical Follow-Up Strategies for the Next Neutrino-Detected Galactic Core-Collapse Supernova

International audienceCore-collapse supernovae (CCSNe) are expected to produce intense bursts of neutrinos preceding the emergence of their electromagnetic (EM) counterparts. The prompt detection of such neutrino signals offers a unique opportunity to trigger early follow-up observations in the EM domain. We aim to assess the feasibility and efficiency of an optical-NIR follow-up strategy for CCSNe discovered via neutrino bursts, by modelling the spatial distribution of events and simulating realistic observational campaigns taking into account the size of the localization error box generated by triangulating the neutrino burst. We modelled the Galactic distribution of CCSNe, including the effects of interstellar extinction, and considered three main progenitor types: Wolf-Rayet stars, red and blue supergiants. We included the shock breakout in the EM signatures that could be detected following the neutrino burst. A population of CCSNe was generated and detected by different networks of neutrino observatories, including IceCube, KM3NeT, Super-Kamiokande, Hyper-Kamiokande, and JUNO. The resulting skymaps were used as input for GWEMOPT to produce optimized follow-up plans with two optical facilities: LSST and the TAROT robotic telescopes. Both LSST and TAROT exhibit comparable detection efficiencies for the simulated CCSN population. However, the TAROT network achieves similar success rates while requiring fewer pointings to cover the CCSN skymap. Our simulations demonstrate that neutrino follow-up campaigns can effectively CCSN optical counterparts using both large and small facilities. Depending on the neutrino network, the median number of pointings for the two tested optical facilities is of the order of 20 to 100 to find the EM emission. The number of images is larger for LSST than for TAROT by a factor of 2 to 4

Standard Sirens in 2040s: Probing the Cosmic Expansion History with Gravitational Waves and Spectroscopic Galaxy Surveys

International audienceGravitational waves (GWs) from compact binary coalescences have matured into a robust cosmological probe, providing self-calibrated luminosity distance measurements independent of any cosmic distance ladder, hence the term "standard sirens". The binary neutron star merger GW170817 delivered the first such measurement of the Hubble constant, demonstrating that GWs offer a path to precision cosmology with systematics orthogonal to standard cosmological probes. To convert GW distances into cosmological parameters, redshift information is essential. To maximize the scientific potential, the redshift must be obtained from individual galaxies, either by identifying electromagnetic counterparts of GW events (bright sirens) or by statistically associating potential hosts within the GW localization volume (dark sirens). The precision of these redshifts sets the achievable accuracy. Forecasts show that photometric uncertainties degrade cosmological constraints by up to an order of magnitude compared to spectroscopic ones. Wide-field, high-multiplex spectroscopic facilities will therefore be an essential infrastructure for GW cosmology in the 2040s