arXiv subjects

Dimitrios K. Papoulias

Publications and source records attributed to Dimitrios K. Papoulias.

At least 19 recordsLinked to original sources

arXiv2026

Can Elastic Neutrino Scattering Account for the LZ230616 Event?

Recently, the LUX-ZEPLIN (LZ) Collaboration reported an isolated nuclear-recoil event at $248\pm 23_\mathrm{stat}\pm 23_\mathrm{syst}~\mathrm{keV_{nr}}$, in a region where the expected background is very small and conventional elastic dark matter (DM)-nucleus scattering cannot readily account for such a localized feature. We investigate whether LZ230616 could instead originate from coherent elastic neutrino-nucleus scattering (CE$ν$NS). We consider neutrino-nucleus interactions within and beyond the Standard Model, together with exotic neutrino fluxes from DM annihilation ($χχ\to ν\barν$) or decay ($χ\to ν\barν$) into neutrino pairs and from primordial black hole (PBH) evaporation. We show that kinematic considerations, the accompanying low energy recoil spectrum, and existing constraints exclude a viable interpretation of LZ230616 in terms of elastic neutrino-nucleus scattering for all scenarios considered.

hep-ph↗

arXiv2026

Refined extraction of electroweak and nuclear parameters from germanium CE$ν$NS data

We present a combined analysis of recent CE$ν$NS data on germanium from two complementary experiments: COHERENT, which uses neutrinos from pion decay at rest, and CONUS+, which detects reactor antineutrinos. Exploiting the complementarity of these two datasets in a joint statistical analysis, we extract the germanium root-mean-square neutron radius and neutron skin with improved precision, disentangling spectral shape distortions from overall normalizations and reducing systematic uncertainties. We also determine the weak mixing angle at low momentum transfer, providing a test of the Standard Model in a less-explored kinematic regime. A key systematic uncertainty in CE$ν$NS ionization measurements is the nuclear quenching factor; we therefore present our results as a function of variations of the Lindhard model. For the nuclear form factor, we adopt the analytical Klein-Nystrand parametrization and benchmark it against predictions from the large-scale nuclear Shell Model, assessing the impact of nuclear structure uncertainties on our results. Our analysis demonstrates the power of combining datasets across different neutrino sources to maximize sensitivity to both nuclear and electroweak physics.

hep-ph↗

arXiv2026

Testing light and heavy vector mediators with solar CE$ν$NS measurements

The recent observation of coherent elastic neutrino-nucleus scattering from solar $^8$B neutrinos in dark matter direct detection experiments has inaugurated the \emph{neutrino fog} era, highlighting the extended potential of these experiments as precision neutrino observatories. Recent measurements by the XENONnT, PandaX-4T, and LUX-ZEPLIN experiments provide new opportunities to test Standard Model predictions and to probe physics beyond it, in complementarity with dedicated neutrino facilities. We perform a combined analysis of nuclear recoil data from these three facilities to extract information on the solar $^8$B neutrino flux normalization and on the weak mixing angle at low-momentum transfer. We further investigate the impact of new vector interactions on the solar neutrino event rate, deriving constraints on nonstandard neutrino interactions and on scenarios with light vector mediators. Our results demonstrate that dark matter detectors are rapidly becoming complementary to terrestrial neutrino experiments in probing neutrino interactions, and already set competitive bounds on both light and heavy vector mediators.

hep-ph↗

arXiv2026

Invisible decay of solar neutrinos at dark matter experiments

The combination of the long baseline and characteristic energies of solar neutrinos offers an ideal framework to probe invisible neutrino decay. In this work we present the first constraint on invisible solar-neutrino decay using coherent elastic neutrino-nucleus scattering, recently observed in dark matter direct detection experiments. Through a combined analysis of nuclear-recoil data from XENONnT, PandaX-4T, and LUX-ZEPLIN, we constrain the lifetime of the neutrino mass state $ν_{2}$, obtaining a bound already comparable in strength to that from the Sudbury Neutrino Observatory. We further evaluate the sensitivity that could be reached by a future xenon-based dark matter detector. For this projection, we extend the analysis to electronic-recoil data, estimating the impact of detecting lower-energy solar neutrinos from the $pp$-chain via elastic scattering off electrons. This channel would allow us to place strong constraints on the lifetimes of both the $ν_{1}$ and $ν_{2}$ mass eigenstates. Our results show that, with nominal future exposures, nuclear-recoil data would improve the current bound by about one order of magnitude, while electronic-recoil data would open a new detection channel for low-energy solar neutrinos, surpassing existing dedicated solar-neutrino bounds by 1 to 2 orders of magnitude.

hep-ph↗

arXiv2026

New light mediators and the neutrino fog: Implications from XENONnT nuclear recoil data

Current ton-scale, xenon-based dark matter (DM) direct detection experiments have now reached the sensitivity required to observe solar neutrinos, marking the onset of the so-called neutrino fog. In this work, we explore how this fog is modified when either neutrinos or DM interact with nuclei through a new scalar, vector or axial-vector interaction, considering both heavy and light mediators. Using the latest nuclear-recoil data from XENONnT, which show indications of coherent elastic neutrino-nucleus scattering from $^8$B solar neutrinos, we derive new strong bounds on couplings of light mediators. We find that these limits are significantly more stringent when the mediator couples to DM, rather than when new physics affects only neutrino interactions. Building on these results, we recompute the expected neutrino fog and compare it with the corresponding constraints on spin-independent and spin-dependent DM-nucleon interactions. We show that the morphology of the neutrino fog can be markedly modified if either neutrinos or DM interact with nuclei through light mediators, even in light of these recent constraints.

hep-ph↗

arXiv2026

Axial-vector neutral-current measurements in coherent elastic neutrino-nucleus scattering experiments

Coherent elastic neutrino-nucleus scattering (CE$ν$NS) is predominantly governed by vector neutral-current interactions, with subleading contributions arising from the axial current in nuclei with non-zero ground-state spin. Experimentally, the extraction of axial-current contributions has been so far of little interest, mainly because of the challenges its measurement entail. In this work, we investigate the relative size of the vector and axial components for target materials currently employed by the neutrino and dark matter experimental communities. We identify fluorine-based compounds as the most promising targets for probing the axial-current event rate. Among them, octafluoropropane ($\text{C}_3\text{F}_8$) emerges as a particularly suitable candidate, given its widespread use in spin-dependent dark matter searches and its relevance for upcoming dedicated CE$ν$NS experiments. Considering both pion decay-at-rest and reactor neutrino fluxes, we show that such measurements can allow an indirect determination of the axial coupling at the $\sim 10\%$ level, depending on flux uncertainties and detector thresholds. We further emphasize that measurements of the axial current will allow to probe spin-dependent new physics scenarios through CE$ν$NS.

hep-ph↗

arXiv2025

Probing conventional and new physics at the ESS with coherent elastic neutrino-nucleus scattering

We explore the potential of the European Spallation Source (ESS) in probing physics within and beyond the Standard Model (SM), based on future measurements of coherent elastic neutrino-nucleus scattering (CE$ν$NS). We consider two SM physics cases, namely the weak mixing angle and the nuclear radius. Regarding physics beyond the SM, we focus on neutrino generalized interactions (NGIs) and on various aspects of sterile neutrino and sterile neutral lepton phenomenology. For this, we explore the violation of lepton unitarity, active-sterile oscillations as well as interesting upscattering channels such as the sterile dipole portal and the production of sterile neutral leptons via NGIs. The projected ESS sensitivities are estimated by performing a statistical analysis considering the various CE$ν$NS detectors and expected backgrounds. We find that the enhanced statistics achievable in view of the highly intense ESS neutrino beam, will offer a drastic improvement in the current constraints obtained from existing CE$ν$NS measurements. Finally, we discuss how the ESS has the potential to provide the leading CE$ν$NS-based constraints, complementing also further experimental probes and astrophysical observations.

hep-ph↗

arXiv2025

Implications of the first CONUS+ measurement of coherent elastic neutrino-nucleus scattering

The CONUS+ collaboration has reported their first observation of coherent elastic neutrino-nucleus scattering (CE$ν$NS). The experiment uses reactor electron antineutrinos and germanium detectors with recoil thresholds as low as $160~\mathrm{eV_\text{ee}}$. With an exposure of $327$ kg $\times$ d, the measurement was made with a statistical significance of $3.7 σ$. We explore several physics implications of this observation, both within the standard model and in the context of new physics. We focus on a determination of the weak mixing angle, nonstandard and generalized neutrino interactions both with heavy and light mediators, neutrino magnetic moments, and the up-scattering of neutrinos into sterile fermions through the sterile dipole portal and new mediators. Our results highlight the role of reactor-based \cevns~experiments in probing a vast array of neutrino properties and new physics models.

hep-ph↗

arXiv2025

Constraining low scale dark hypercharge symmetry at spallation, reactor and Dark Matter direct detection experiments

Coherent elastic neutrino-nucleus (CE$ν$NS) and elastic neutrino-electron scattering (E$ν$ES) data are exploited to constrain ``chiral'' $U(1)_{X}$ gauged models with light vector mediator mass. These models fall under a distinct class of new symmetries called dark hypercharge symmetries. A key feature is the fact that the $Z'$ boson can couple to all Standard Model fermions at tree level, with the $U(1)_X$ charges determined by the requirement of anomaly cancellation. Notably, the charges of leptons and quarks can differ significantly depending on the specific anomaly cancellation solution. As a result, different models exhibit distinct phenomenological signatures and can be constrained through various experiments. In this work, we analyze the recent data from the COHERENT experiment, along with results from dark matter (DM) direct detection experiments such as XENONnT, LUX-ZEPLIN, and PandaX-4T, and place new constraints on three benchmark models. Additionally, we set constraints from a performed analysis of TEXONO data and discuss the prospects of improvement in view of the next-generation DM direct detection DARWIN experiment.

hep-ph↗

arXiv2025

Inelastic neutrino-nucleus scattering off $^{203/205}$Tl in terms of the nuclear recoil energy using a hybrid nuclear model

Nuclear structure calculations in the context of a novel hybrid nuclear model, combining the nuclear shell model and the microscopic quasiparticle-phonon model are presented. The predictivity of the hybrid model is tested by computing inelastic neutral-current neutrino-nucleus scattering cross sections off the stable thallium isotopes. The cross sections are presented in terms of the incoming neutrino energy, taking also into account the effect of nuclear recoil energy. Also reported are the expected event rates assuming neutrinos emerging from pion-decay at rest and the diffuse supernova neutrino background. Regarding solar neutrino rates, new results are presented in the context of the hybrid model and compared with previously reported results based solely on nuclear shell model calculations, demonstrating the improved accuracy of the adopted hybrid model at higher neutrino energies.

nucl-th↗

arXiv2024

Neutrino electromagnetic properties and sterile dipole portal in light of the first solar CE$ν$NS data

Despite being neutral particles, neutrinos can acquire non-zero electromagnetic properties from radiative corrections that can be induced by the presence of new physics. Electromagnetic neutrino processes induce spectral distortions in neutrino scattering data, which are especially visible at experiments characterized by low recoil thresholds. We investigate how neutrino electromagnetic properties confront the recent indication of coherent elastic neutrino-nucleus scattering (CE$ν$NS) from $^8$B solar neutrinos in dark matter direct detection experiments. We focus on three possibilities: neutrino magnetic moments, neutrino electric charges, and the active-sterile transition magnetic moment portal. We analyze recent XENONnT and PandaX-4T data and infer the first \cevns-based constraints on electromagnetic properties using solar $^8$B neutrinos.

hep-ph↗

arXiv2024

Bounds on new neutrino interactions from the first CE$ν$NS data at direct detection experiments

Recently, two dark matter direct detection experiments have announced the first indications of nuclear recoils from solar $^8$B neutrinos via coherent elastic neutrino-nucleus scattering (CE$ν$NS) with xenon nuclei. These results constitute a turning point, not only for dark matter searches that are now entering the \textit{neutrino fog}, but they also bring out new opportunities to exploit dark matter facilities as neutrino detectors. We investigate the implications of recent data from the PandaX-4T and XENONnT experiments on both Standard Model physics and new neutrino interactions. We first extract information on the weak mixing angle at low momentum transfer. Then, following a phenomenological approach, we consider Lorentz-invariant interactions (scalar, vector, axial-vector, and tensor) between neutrinos, quarks and charged leptons. Furthermore, we study the $U(1)_\mathrm{B-L}$ scenario as a concrete example of a new anomaly-free vector interaction. We find that despite the low statistics of these first experimental results, the inferred bounds are in some cases already competitive. For the scope of this work we also compute new bounds on some of the interactions using CE$ν$NS data from COHERENT and electron recoil data from XENONnT, LUX-ZEPLIN, PandaX-4T, and TEXONO. It seems clear that while direct detection experiments continue to take data, more precise measurements will be available, thus allowing to test new neutrino interactions at the same level or even improving over dedicated neutrino facilities.

hep-ph↗

arXiv2024

Incoherent solar-neutrino scattering off the stable Tl-isotopes

Nuclear-structure calculations for the description of low-energy neutral-current neutrino scattering off the stable $^{203,205}$Tl isotopes are performed in the context of the nuclear shell model using the model space jj56pn. Cross-section and event-rate calculations focusing on inelastic solar-neutrino scattering off $^{203,205}$Tl are performed. The individual contributions of the various nuclear responses are presented and discussed, and the results are also illustrated in terms of the nuclear recoil energy. Analytical expressions entering the cross sections are given in order to achieve a direct connection with experimental observables.

nucl-th↗

arXiv2024

Up-scattering production of a sterile fermion at DUNE: complementarity with spallation source and direct detection experiments

We investigate the possible production of a MeV-scale sterile fermion through the up-scattering of neutrinos on nuclei and atomic electrons at different facilities. We consider a phenomenological model that adds a new fermion to the particle content of the Standard Model and we allow for all possible Lorentz-invariant non-derivative interactions (scalar, pseudoscalar, vector, axial-vector and tensor) of neutrinos with electrons and first-generation quarks. We first explore the sensitivity of the DUNE experiment to this scenario, by simulating elastic neutrino-electron scattering events in the near detector. We consider both options of a standard and a tau-optimized neutrino beams, and investigate the impact of a mobile detector that can be moved off-axis with respect to the beam. Next, we infer constraints on the typical coupling, new fermion and mediator masses from elastic neutrino-electron scattering events induced by solar neutrinos in two current dark matter direct detection experiments, XENONnT and LZ. Under the assumption that the new mediators couple also to first-generation quarks, we further set constraints on the up-scattering production of the sterile fermion using coherent elastic neutrino-nucleus scattering data from the COHERENT experiment. Moreover, we set additional constraints assuming that the sterile fermion may decay within the detector. We finally compare our results and discuss how these facilities are sensitive to different regions of the relevant parameter space due to kinematics arguments and can hence provide complementary information on the up-scattering production of a sterile fermion.

hep-ph↗

arXiv2024

Light vector mediators at direct detection experiments

Solar neutrinos induce elastic neutrino-electron scattering in dark matter direct detection experiments, resulting in detectable event rates at current facilities. We analyze recent data from the XENONnT, LUX-ZEPLIN, and PandaX-4T experiments and we derive stringent constraints on several $U(1)'$ extensions of the Standard Model, accommodating new neutrino-electron interactions. We provide bounds on the relevant coupling and mass of light vector mediators for a variety of models, including the anomaly-free $B-L$ model, lepton flavor-dependent interactions like $L_α- L_β$, $B-2L_e - L_{μ, τ}$, $B-3L_α$, and $B+2L_μ+2 L_τ$ models. We compare our results with other limits obtained in the literature from both terrestrial and astrophysical experiments. Finally, we present forecasts for improving current bounds with a future experiment like DARWIN.

hep-ph↗

arXiv2024

XENONnT and LUX-ZEPLIN constraints on DSNB-boosted dark matter

We consider a scenario in which dark matter particles are accelerated to semi-relativistic velocities through their scattering with the Diffuse Supernova Neutrino Background. Such a subdominant, but more energetic dark matter component can be then detected via its scattering on the electrons and nucleons inside direct detection experiments. This opens up the possibility to probe the sub-GeV mass range, a region of parameter space that is usually not accessible at such facilities. We analyze current data from the XENONnT and LUX-ZEPLIN experiments and we obtain novel constraints on the scattering cross sections of sub-GeV boosted dark matter with both nucleons and electrons. We also highlight the importance of carefully taking into account Earth's attenuation effects as well as the finite nuclear size into the analysis. By comparing our results to other existing constraints, we show that these effects lead to improved and more robust constraints.

hep-ph↗

arXiv2023

COHERENT production of a dark fermion

We consider the possible production of a new MeV-scale fermion at the COHERENT experiment. The new fermion, belonging to a dark sector, can be produced through the up-scattering process of neutrinos off the nuclei and the electrons of the detector material, via the exchange of a light vector or scalar mediator. We perform a detailed statistical analysis of the combined COHERENT CsI and LAr data sets and obtain up-to-date constraints on the couplings and masses of the dark fermion and mediators. We finally briefly comment about the stability of the dark fermion.

hep-ph↗

arXiv2023

Probing generalized neutrino interactions with the DUNE Near Detector

We explore the prospects of constraining general non standard interactions involving light mediators through elastic neutrino-electron scattering events at the DUNE Near Detector (ND). We furthermore consider the special cases of light vector mediators in motivated models such as $U(1)_{B-L}$, $U(1)_{L_μ- L_τ}$, $E_6$ and left-right symmetry. The present analysis is based on detailed Monte Carlo simulations of the expected DUNE-ND signal taking into account detector resolution effects, realistic backgrounds as well as On-Axis and Off-Axis neutrino spectra. We show that the high intensity neutrino beam available at Fermilab can place competitive constraints surpassing those of low-energy neutrino searches and direct detection dark matter experiments.

hep-ph↗