arXiv subjects

D. K. Papoulias

Publications and source records attributed to D. K. Papoulias.

At least 19 recordsLinked to original sources

arXiv2026

Sensitivity to sub-GeV dark matter in forthcoming spallation-source neutrino experiments

Sub-GeV thermal dark matter weakly interacting with the Standard Model through vector-portal mediators provides a well-motivated and predictive framework that remains challenging to probe with conventional direct detection experiments. Motivated by the rapid development of neutrino facilities based on spallation neutron sources, we study the sensitivity of future coherent elastic neutrino-nucleus scattering experiments to light dark matter produced in neutral pion decays. We consider scalar dark matter interactions mediated by two different vector portals, a generic dark photon and a baryophilic vector mediator. The neutral pion yield is calculated through a GEANT4 simulation and the results are compared with those obtained with the Sandford-Wang parametrization. We show that predictions based on either approach do not produce significant differences. Our results demonstrate that upcoming low-threshold neutrino detectors at the European Spallation Source (ESS), the Japan Proton Accelerator Research Complex (J-PARC) and the China Spallation Neutron Source (CSNS) may test regions in parameter space not yet explored, or be competitive with existing bounds. We point out that these facilities will strengthen the global experimental program searching for secluded sectors.

hep-ph↗

arXiv2023

Physics implications of a combined analysis of COHERENT CsI and LAr data

The observation of coherent elastic neutrino nucleus scattering has opened the window to many physics opportunities. This process has been measured by the COHERENT Collaboration using two different targets, first CsI and then argon. Recently, the COHERENT Collaboration has updated the CsI data analysis with a higher statistics and an improved understanding of systematics. Here we perform a detailed statistical analysis of the full CsI data and combine it with the previous argon result. We discuss a vast array of implications, from tests of the Standard Model to new physics probes. In our analyses we take into account experimental uncertainties associated to the efficiency as well as the timing distribution of neutrino fluxes, making our results rather robust. In particular, we update previous measurements of the weak mixing angle and the neutron root mean square charge radius for CsI and argon. We also update the constraints on new physics scenarios including neutrino nonstandard interactions and the most general case of neutrino generalized interactions, as well as the possibility of light mediators. Finally, constraints on neutrino electromagnetic properties are also examined, including the conversion to sterile neutrino states. In many cases, the inclusion of the recent CsI data leads to a dramatic improvement of bounds.

hep-ph↗

arXiv2022

Consequences of the Dresden-II reactor data for the weak mixing angle and new physics

The Dresden-II reactor experiment has recently reported a suggestive evidence for the observation of coherent elastic neutrino-nucleus scattering, using a germanium detector. Given the low recoil energy threshold, these data are particularly interesting for a low-energy determination of the weak mixing angle and for the study of new physics leading to spectral distortions at low momentum transfer. Using two hypotheses for the quenching factor, we study the impact of the data on: (i) The weak mixing angle at a renormalization scale of $\sim 10\,\text{MeV}$, (ii) neutrino generalized interactions with light mediators, (iii) the sterile neutrino dipole portal. The results for the weak mixing angle show a strong dependence on the quenching factor choice. Although still with large uncertainties, the Dresden-II data provide for the first time a determination of $\sin^2θ_W$ at such scale using coherent elastic neutrino-nucleus scattering data. Tight upper limits are placed on the light vector, scalar and tensor mediator scenarios. Kinematic constraints implied by the reactor anti-neutrino flux and the ionization energy threshold allow the sterile neutrino dipole portal to produce up-scattering events with sterile neutrino masses up to $\sim 8\,$MeV. In this context, we find that limits are also sensitive to the quenching factor choice, but in both cases competitive with those derived from XENON1T data and more stringent that those derived with COHERENT data, in the same sterile neutrino mass range.

hep-ph↗

arXiv2022

Dark matter detectors as a novel probe for light new physics

We explore the prospect of constraining light mediators at the next generation direct detection dark matter detectors through coherent elastic neutrino-nucleus scattering (CE$ν$NS) and elastic neutrino-electron scattering (E$ν$ES) measurements. Taking into account various details like the quenching factor corrections, atomic binding effects, realistic backgrounds, detection efficiency, energy resolution etc., we consider two representative scenarios regarding detector specifications. For both scenarios, we obtain the model-independent projected sensitivities for all possible Lorentz-invariant interactions, namely scalar ($S$), pseudoscalar ($P$), vector ($V$), axial vector ($A$) and tensor ($T$). For the case of vector interactions, we also focus on two concrete examples: the well-known $U(1)_{B-L}$ and $U(1)_{L_μ- L_τ}$ gauge symmetries. For all interaction channels $X=\{S,P,V,A,T\}$, our results imply that the upcoming dark matter detectors have the potential to place competitive constraints, improved by about 1 order of magnitude compared to existing ones from dedicated CE$ν$NS experiments, XENON1T, beam dump experiments and collider probes.

hep-ph↗

arXiv2022

Impact of COHERENT measurements, cross section uncertainties and new interactions on the neutrino floor

We reconsider the discovery limit of multi-ton direct detection dark matter experiments in the light of recent measurements of the coherent elastic neutrino-nucleus scattering process. Assuming the cross section to be a parameter entirely determined by data, rather than using its Standard Model prediction, we use the COHERENT CsI and LAr data sets to determine WIMP discovery limits. Being based on a data-driven approach, the results are thus free from theoretical assumptions and fall within the WIMP mass regions where XENONnT and DARWIN have best expected sensitivities. We further determine the impact of subleading nuclear form factor and weak mixing angle uncertainties effects on WIMP discovery limits. We point out that these effects, albeit small, should be taken into account. Moreover, to quantify the impact of new physics effects in the neutrino background, we revisit WIMP discovery limits assuming light vector and scalar mediators as well as neutrino magnetic moments/transitions. We stress that the presence of new interactions in the neutrino sector, in general, tend to worsen the WIMP discovery limit.

hep-ph↗

arXiv2022

Low-energy probes of sterile neutrino transition magnetic moments

Sterile neutrinos with keV-MeV masses and non-zero transition magnetic moments can be probed through low-energy nuclear or electron recoil measurements. Here we determine the sensitivities of current and future searches, showing how they can probe a previously unexplored parameter region. Future coherent elastic neutrino-nucleus scattering (CE$ν$NS) or elastic neutrino-electron scattering (E$ν$ES) experiments using a monochromatic $^{51}$Cr source can fully probe the region indicated by the recent XENON1T excess.

hep-ph↗

arXiv2022

Coherent elastic neutrino-nucleus scattering (CE$ν$NS) event rates for Ge, Zn and Si detector materials

Realistic nuclear structure calculations are presented for the event rates due to coherent elastic neutrino-nucleus scattering (CE$ν$NS), assuming neutrinos from pion-decay at-rest, from nuclear reactors and from Earth's interior. We focus on the currently interesting Germanium isotopes, $^{70,73,76}$Ge, which constitute detector materials of the recently planned CE$ν$NS experiments. We study in addition the potential use of $^{64,70}$Zn and $^{28}$Si isotopes as promising CE$ν$NS detectors. From nuclear physics perspectives, recently, calculations have been carried out within the framework of the deformed shell-model (DSM), based on realistic nuclear forces, and assessed on the reproducibility of spectroscopic nuclear properties. The high confidence level acquired by their agreement with experimental results and by their comparison with other mostly phenomenological calculations encouraged the use of DSM to extract predictions for the CE$ν$NS event rates of the above isotopes. Our detailed estimation of the nuclear physics aspects of the recently observed neutral current coherent neutrino-nucleus scattering may shed light on unravelling the still remaining uncertainties for the CE$ν$NS process within and beyond the Standard Model.

nucl-th↗

arXiv2021

Neutrino magnetic and electric dipole moments: From measurements to parameter space

Searches for neutrino magnetic moments/transitions in low energy neutrino scattering experiments are sensitive to effective couplings which are an intricate function of the Hamiltonian parameters. We study the parameter space dependence of these couplings in the Majorana (transitions) and Dirac (moments) cases, as well as the impact of the current most stringent experimental upper limits on the fundamental parameters. In the Majorana case we find that for reactor, short-baseline and solar neutrinos, CP violation can be understood as a measurement of parameter space vectors misalignments. The presence of nonvanishing CP phases opens a blind spot region where -- regardless of how large the parameters are -- no signal can be observed in either reactor or short-baseline experiments. Identification of these regions requires a combination of different data sets and allows for the determination of those CP phases. We point out that stringent bounds not necessarily imply suppressed Hamiltonian couplings, thus allowing for regions where disparate upper limits can be simultaneously satisfied. In contrast, in the Dirac case stringent experimental upper limits necessarily translate into tight bounds on the fundamental couplings. In terms of parameter space vectors, we provide a straightforward mapping of experimental information into parameter space.

hep-ph↗

arXiv2020

Future CEvNS experiments as probes of lepton unitarity and light-sterile neutrinos

We determine the sensitivities of short-baseline coherent elastic neutrino-nucleus scattering (CE$ν$NS) experiments using a pion decay at rest neutrino source as a probe for nonunitarity in the lepton sector, as expected in low-scale type-I seesaw schemes. We also identify the best configuration for probing light sterile neutrinos at future ton-scale liquid argon CE$ν$NS experiments, estimating the projected sensitivities on the sterile neutrino parameters. Possible experimental setups at the Spallation Neutron Source, Lujan facility and the European Spallation Source are discussed. Provided that systematic uncertainties remain under control, we find that CE$ν$NS experiments will be competitive with oscillation measurements in the long run.

hep-ph↗

arXiv2020

Implications of the first detection of coherent elastic neutrino-nucleus scattering (CEvNS) with Liquid Argon

The CENNS-10 experiment of the COHERENT collaboration has recently reported the first detection of coherent-elastic neutrino-nucleus scattering (CEvNS) in liquid Argon with more than $3 σ$ significance. In this work, we exploit the new data in order to probe various interesting parameters which are of key importance to CEvNS within and beyond the Standard Model. A dedicated statistical analysis of these data shows that the current constraints are significantly improved in most cases. We derive a first measurement of the neutron rms charge radius of Argon, and also an improved determination of the weak mixing angle in the low energy regime. We also update the constraints on neutrino non-standard interactions, electromagnetic properties and light mediators with respect to those derived from the first COHERENT-CsI data.

hep-ph↗

arXiv2020

Axionlike particles searches in reactor experiments

Reactor neutrino experiments provide a rich environment for the study of axionlike particles (ALPs). Using the intense photon flux produced in the nuclear reactor core, these experiments have the potential to probe ALPs with masses below 10 MeV. We explore the feasibility of these searches by considering ALPs produced through Primakoff and Compton-like processes as well as nuclear transitions. These particles can subsequently interact with the material of a nearby detector via inverse Primakoff and inverse Compton-like scatterings, via axio-electric absorption, or they can decay into photon or electron-positron pairs. We demonstrate that reactor-based neutrino experiments have a high potential to test ALP-photon couplings and masses, currently probed only by cosmological and astrophysical observations, thus providing complementary laboratory-based searches. We furthermore show how reactor facilities will be able to test previously unexplored regions in the $\sim$MeV ALP mass range and ALP-electron couplings of the order of $g_{aee} \sim 10^{-8}$ as well as ALP-nucleon couplings of the order of $g_{ann}^{(1)} \sim 10^{-9}$, testing regions beyond TEXONO and Borexino limits.

hep-ph↗

arXiv2020

Elastic and inelastic scattering of neutrinos and weakly interacting massive particles on nuclei

The event rates for WIMP-nucleus and neutrino-nucleus scattering processes, expected to be detected in ton-scale rare-event detectors, are investigated. We focus on nuclear isotopes that correspond to the target nuclei of current and future experiments looking for WIMP- and neutrino-nucleus events. The nuclear structure calculations, performed in the context of the deformed shell model, are based on Hartree-Fock intrinsic states with angular momentum projection and band mixing for both the elastic and the inelastic channels. Our predictions in the high-recoil-energy tail show that detectable distortions of the measured/expected signal may be interpreted through the inclusion of the non-negligible incoherent channels

nucl-th↗

arXiv2020

Light vector mediators facing XENON1T data

Recently the XENON1T collaboration has released new results on searches for new physics in low-energy electronic recoils. The data shows an excess over background in the low-energy tail, particularly pronounced at about $2-3$ keV. With an exposure of $0.65$ tonne-year, large detection efficiency and energy resolution, the detector is sensitive as well to solar neutrino backgrounds, with the most prominent contribution given by $pp$ neutrinos. We investigate whether such signal can be explained in terms of new neutrino interactions with leptons mediated by a light vector particle. We find that the excess is consistent with this interpretation for vector masses below $\lesssim 0.1$ MeV. The region of parameter space probed by the XENON1T data is competitive with constraints from laboratory experiments, in particular GEMMA, Borexino and TEXONO. However we point out a severe tension with astrophysical bounds and cosmological observations.

hep-ph↗

arXiv2020

XENON1T signal from transition neutrino magnetic moments

The recent puzzling results of the XENON1T collaboration at few keV electronic recoils could be due to the scattering of solar neutrinos endowed with finite Majorana transition magnetic moments (TMMs). Within such general formalism, we find that the observed excess in the XENON1T data agrees well with this interpretation. The required TMM strengths lie within the limits set by current experiments, such as Borexino, specially when one takes into account a possible tritium contamination.

hep-ph↗

arXiv2019

Constraining nuclear physics parameters with current and future COHERENT data

Motivated by the recent observation of coherent elastic neutrino-nucleus scattering (CE$ν$NS) at the COHERENT experiment, our goal is to explore its potential in probing important nuclear structure parameters. We show that the recent COHERENT data offers unique opportunities to investigate the neutron nuclear form factor. Our present calculations are based on the deformed Shell Model (DSM) method which leads to a better fit of the recent CE$ν$NS data, as compared to known phenomenological form factors such as the Helm-type, symmetrized Fermi and Klein-Nystrand. The attainable sensitivities and the prospects of improvement during the next phase of the COHERENT experiment are also considered and analyzed in the framework of two upgrade scenarios.

hep-ph↗

arXiv2019

Recent probes of standard and non-standard neutrino physics with nuclei

We review standard and non-standard neutrino physics probes that are based on nuclear measurements. We pay special attention on the discussion of prospects to extract new physics at prominent rare event measurements looking for neutrino-nucleus scattering, such as the coherent elastic neutrino-nucleus scattering (CE$ν$NS) that may involve lepton flavor violation (LFV) in neutral-currents (NC). For the latter processes several appreciably sensitive experiments are currently pursued or have been planed to operate in the near future, like the COHERENT, CONUS, CONNIE, MINER, TEXONO, RED100, vGEN, Ricochet, NUCLEUS etc. We provide a thorough discussion on phenomenological and theoretical studies, in particular those referring to the nuclear physics aspects in order to provide accurate predictions for the relevant experiments. Motivated by the recent discovery of CE$ν$NS at the COHERENT experiment and the active experimental efforts for a new measurement at reactor-based experiments, we summarize the current status of the constraints as well as the future sensitivities on nuclear and electroweak physics parameters, non-standard interactions, electromagnetic neutrino properties, sterile neutrinos and simplified scenarios with novel vector $Z^\prime$ or scalar $ϕ$ mediators. Indirect and direct connections of \cevns with astrophysics, direct Dark Matter detection and charge lepton flavor violating processes are also discussed.

hep-ph↗

arXiv2019

Probing neutrino transition magnetic moments with coherent elastic neutrino-nucleus scattering

We explore the potential of current and next generation of coherent elastic neutrino-nucleus scattering (CE$ν$NS) experiments in probing neutrino electromagnetic interactions. On the basis of a thorough statistical analysis, we determine the sensitivities on each component of the Majorana neutrino transition magnetic moment (TMM), $\left \vert Λ_i \right \vert$, that follow from low-energy neutrino-nucleus experiments. We derive the sensitivity to neutrino TMM from the first CE$ν$NS measurement by the COHERENT experiment, at the Spallation Neutron Source. We also present results for the next phases of COHERENT using HPGe, LAr and NaI[Tl] detectors and for reactor neutrino experiments such as CONUS, CONNIE, MINER, TEXONO and RED100. The role of the CP violating phases in each case is also briefly discussed. We conclude that future CE$ν$NS experiments with low-threshold capabilities can improve current TMM limits obtained from Borexino data.

hep-ph↗

arXiv2018

Novel neutrino-floor and dark matter searches with deformed shell model calculations

Event detection rates for WIMP-nucleus interactions are calculated for $^{71}$Ga, $^{73}$Ge, $^{75}$As and $^{127}$I (direct dark matter detectors). The nuclear structure form factors, that are rather independent of the underlying beyond the Standard Model particle physics scenario assumed, are evaluated within the context of the deformed nuclear shell model (DSM) based on Hartree-Fock nuclear states. Along with the previously published DSM results for $^{73}$Ge, the neutrino-floor due to coherent elastic neutrino-nucleus scattering (CE$ν$NS), an important source of background to dark matter searches, is extensively calculated. The impact of new contributions to CE$ν$NS due to neutrino magnetic moments and $Z^\prime$ mediators at direct dark matter detection experiments is also examined and discussed. The results show that the neutrino-floor constitutes a crucial source of background events for multi-ton scale detectors with sub-keV capabilities.

hep-ph↗