arXiv subjects

Christoph A. Ternes

Publications and source records attributed to Christoph A. Ternes.

At least 19 recordsLinked to original sources

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

Probing damping effects in neutrino oscillations with the first JUNO data

We consider different scenarios which lead to a damping of the neutrino oscillation probability and investigate their impact on the first JUNO results. First, we study decoherence effects due to wave packet separation. In addition, we consider an open quantum system framework and adopt a phenomenological approach which allows us to parameterize the energy dependence of the decoherence effects more freely. Finally, we study the effect of invisible neutrino decay. In all cases with the first data JUNO can already place competitive bounds on the parameter space of the scenarios under consideration, while also maintaining a robust measurement of the standard neutrino oscillation parameters.

hep-ph↗

arXiv2026

Prospects for precision CE$ν$NS measurements with electron-capture neutrinos and lithium-based bolometers

We evaluate the feasibility of high-precision coherent elastic neutrino-nucleus scattering measurements exploiting mono-energetic neutrinos produced by electron-capture (EC) decays of intense radioactive sources, such as $^{51}$Cr or $^{37}$Ar. To fully exploit the high neutrino flux achievable with EC sources, and accounting for the low energy of EC neutrinos, we evaluate the sensitivity of a compact array of bolometric detectors with absorbers based on light elements, such as lithium, oxygen and fluorine. With 1 kg of LiF detectors, source activities of $\sim10^{17}$ Bq, and assuming an energy threshold of 20 eV, we expect to achieve a $\sim 3\%$ precision on the determination of the neutrino flux with 90 days of measurement. Such a measurement would represent a test of the gallium neutrino anomaly, and could disentangle nuclear effects on gallium from the misevaluation of the EC source activity or short-baseline neutrino oscillations.

hep-ph↗

arXiv2025

Standard Model Tested with Neutrinos

The Standard Model (SM) of particle physics effectively explains most observed phenomena, though some anomalies, especially in the neutrino sector, suggest the need for extensions. In this Letter, we perform the first global fit of elastic neutrino-nucleus and neutrino-electron scattering data to further test the SM within a consistent framework. Our results on the neutrino charge radius, the only nonzero electromagnetic property of neutrinos in the SM, show no significant deviation, indicating no large beyond the SM flavor-dependent effects for electron and muon neutrinos. By incorporating solar neutrino data from dark matter direct detection experiments, we also place the most stringent constraints on the tau neutrino charge radius obtained from neutrino scattering experiments. Additionally, we determine updated constraints on the vector and axial-vector neutrino-electron neutral current couplings, adjusting for flavor-dependent effects and for the different experimental momentum transfers. The global analysis reveals two allowed solutions: one close to the SM prediction, and a degenerate solution that is favored. We show that future dark matter detectors could achieve sufficient precision to resolve the degeneracy. As we move toward the precision era, this Letter demonstrates the crucial need to properly account for flavor- and momentum-dependent effects to avoid misinterpretations of the data.

hep-ph↗

arXiv2025

Neutrino magnetic moments: effective versus fundamental parameters

The search for neutrino magnetic moments offers a valuable window into physics beyond the Standard Model. However, a common misconception arises in the interpretation of experimental results: the assumption that the so-called effective neutrino magnetic moment is a universal, experiment-independent quantity. In reality, this effective parameter depends on the specific characteristics of each experiment, including the neutrino source, flavor composition or energy spectrum. As a result, the effective magnetic moment derived from solar neutrino data differs fundamentally from that obtained in reactor or accelerator-based experiments. Treating these quantities as directly comparable can lead to misleading conclusions. In this work, we clarify the proper definition of the effective neutrino magnetic moment in various experimental contexts and discuss the implications of this misconception for global analyses and theoretical interpretations.

hep-ph↗

arXiv2025

SN1987A bounds on neutrino quantum decoherence

We obtain stringent bounds on neutrino quantum decoherence from the analysis of SN1987A data. We show that for the decoherence model considered here, which allows for neutrino-loss along the trajectory, the bounds are many orders of magnitude stronger than the ones that can be obtained from the analysis of data from reactor neutrino oscillation experiments or neutrino telescopes.

hep-ph↗

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

Addendum to `Combined Analysis of Neutrino Decoherence at Reactor Experiments'

We update our analyses to constrain neutrino decoherence induced by wave-packet separation with RENO and Daya Bay data, now including the final data sets of the two experiments. We find that while the individual bounds from Daya Bay and RENO data improve relative to our original estimates, the combined fits are still dominated by KamLAND data and are only minimally improved.

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

Invisible neutrino decay at long-baseline neutrino oscillation experiments

We perform an updated analysis of long-baseline accelerator data in the framework of neutrino oscillations in presence of invisible neutrino decay. We analyze data from T2K, NOvA and MINOS/MINOS+ and show that the combined analysis of all experiments improves the previous bound from long-baseline data by approximately one order of magnitude.

hep-ph↗

arXiv2024

Observing neutrinos from failed Supernovae at LNGS

We discuss the possibility to observe neutrinos emitted from a failed core collapse Supernova in the various experiments at Laboratori Nazionali del Gran Sasso. We show that the veto regions of dark matter and neutrinoless double beta decay experiments can be used as a network of small detectors to measure Supernova neutrinos. In addition we show that this network can measure very precisely the moment of black hole formation, which can be then used in the nearby VIRGO detector and future Einstein Telescope to look for the gravitational wave counterpart to the neutrino signal.

astro-ph.HE↗

arXiv2024

Reactor neutrino background in third-generation dark matter detectors

Third-generation dark matter detectors will be fully sensitive to the boron-8 solar neutrino flux. Because of this, the characterization of such a background has been the subject of extensive analyses over the last few years. In contrast, little is known about the impact of reactor neutrinos. In this letter we report on the implications of such a flux for dark matter direct detection searches. We consider five potential detector deployment sites envisioned by the recently established XLZD consortium: SURF, SNOLAB, Kamioka, LNGS and Boulby. By using public reactor data we construct five reactor clusters -- involving about 100 currently operating commercial nuclear reactors each -- and determine the net neutrino flux at each detector site. Assuming a xenon-based detector and a 50 tonne-year exposure, we show that in all cases the neutrino event rate may be sizable, depending on energy recoil thresholds. Of all possible detector sites, SURF and LNGS are those with the smallest reactor neutrino background. On the contrary, SNOLAB and Boulby are subject to the strongest reactor neutrino fluxes, with Kamioka being subject to a more moderate background. Our findings demonstrate that reactor neutrino fluxes should be taken into account in the next round of dark matter searches. We argue that this background may be particularly relevant for directional detectors, provided they meet the requirements we have employed in this analysis.

hep-ph↗

arXiv2023

Confronting solutions of the Gallium Anomaly with reactor rate data

Recently, several models have been suggested to reduce the tension between Gallium and reactor antineutrino spectral ratio data which is found in the framework of 3+1 active-sterile neutrino mixing. Among these models, we consider the extensions of 3+1 mixing with a finite wavepacket size, or the decay of the heaviest neutrino $ν_4$, or the possibility to have a broad $ν_4$ mass distribution. We consider the reactor antineutrino rate data and we show that these models cannot liminate the tension between Gallium and reactor rate data that is found in the 3+1 neutrino mixing framework. Indeed, we show that the parameter goodness of fit remains small. We consider also a model which explains the Gallium Anomaly with non-standard decoherence in the framework of three-neutrino mixing. We find that it is compatible with the reactor rate data.

hep-ph↗

arXiv2023

Testing neutrino electromagnetic properties at current and future dark matter experiments

We analyze data from the dark matter direct detection experiments PandaX-4T, LUX-ZEPLIN and XENONnT to place bounds on neutrino electromagnetic properties (magnetic moments, millicharges, and charge radii). We also show how these bounds will improve at the future facility DARWIN. In our analyses we implement a more conservative treatment of background uncertainties than usually done in the literature. From the combined analysis of all three experiments we can place very strong bounds on the neutrino magnetic moments and on the neutrino millicharges. We show that even though the bounds on the neutrino charge radii are not very strong from the analysis of current data, DARWIN could provide the first measurement of the electron neutrino charge radius, in agreement with the Standard Model prediction.

hep-ph↗

arXiv2023

Neutrino oscillation bounds on quantum decoherence

We consider quantum-decoherence effects in neutrino oscillation data. Working in the open quantum system framework we adopt a phenomenological approach that allows to parameterize the energy dependence of the decoherence effects. We consider several phenomenological models. We analyze data from the reactor experiments RENO, Daya Bay and KamLAND and from the accelerator experiments NOvA, MINOS/MINOS+ and T2K. We obtain updated constraints on the decoherence parameters quantifying the strength of damping effects, which can be as low as $Γ_{ij} \lesssim 8 \times 10^{-27}$ GeV at 90% confidence level in some cases. We also present sensitivities for the future facilities DUNE and JUNO.

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