Constraints on Millicharged Neutrinos via Atomic Ionizations with Germanium Detectors at sub-keV Sensitivities
Abstract and Figures
With the advent of detectors with sub-keV sensitivities, atomic ionization
has been identified as a promising avenue to probe possible neutrino
electromagnetic properties. The interaction cross-sections induced by
millicharged neutrinos are evaluated with the ab-initio multi-configuration
relativistic random-phase approximation. There is significant enhancement at
atomic binding energies compared to that when the electrons are taken as free
particles. Positive signals would distinctly manifest as peaks at specific
energies with known intensity ratios. Selected reactor neutrino data with
germanium detectors at analysis threshold as low as 300 eV are studied. No such
signatures are observed, and a combined limit on the neutrino charge fraction
of $| \numq | < 1.0 \times 10^{-12}$ at 90% confidence level is derived.
![Germanium photo-ionization cross section. The solid curve corresponds to the results of MCRRPA calculation. The dotted line is a fit to experimental data taken from Ref. [22]. The relative differences (excess of MCRRPA results over data relative to the measurements) are shown in the lower panel.](https://www.researchgate.net/profile/Hsin-Chang-Chi/publication/262690590/figure/fig1/AS:669010144272384@1536515856056/Germanium-photo-ionization-cross-section-The-solid-curve-corresponds-to-the-results-of_Q320.jpg)
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... The signal event rate in the detector, in this case, scales as ∼ðg 4 B−L Zm e E ν =m 4 Z 0 Þ, where g B−L ; m e ; E ν are the Z 0 coupling strength, the mass of electron, and the neutrino energy, respectively, and Z is the charge of the target nuclei. Recently, severe limits on the B − L Z 0 excluding the coupling strength range 10 −6 ≲ g B−L ≲ 10 −2 have been obtained for the masses 1 keV ≲ m Z 0 ≲ 1 GeV [19,29,30] from the results of neutrino-electron scattering experiments, such as TEXONO [31][32][33] and GEMMA [34] at nuclear reactors, BOREXINO [35] using solar neutrinos, LSND [36], and CHARM II [37] at neutrino beams from accelerators, leaving, however, a significant area of the parameter space still unexplored. ...
... For the latter case, three degenerate heavy neutrino species with the mass ratio m N i =m Z 0 ¼ 1=3 have been assumed. Constraints from the results of neutrino-electron scattering experiments obtained with nuclear-reactor neutrinos at TEXONO [31][32][33] and GEMMA [34], solar neutrinos at BOR-EXINO [35], and accelerator neutrino beams at LSND [36] and CHARM II [37] derived in Refs. [19,29] are also shown. ...
A search for a new Z′ gauge boson associated with (un)broken B−L symmetry in the keV–GeV mass range is carried out for the first time using the missing-energy technique in the NA64 experiment at the CERN SPS. From the analysis of the data with 3.22×1011 electrons on target collected during 2016–2021 runs, no signal events were found. This allows us to derive new constraints on the Z′−e coupling strength, which, for the mass range 0.3≲mZ′≲100 MeV, are more stringent compared to those obtained from the neutrino-electron scattering data.
... Our bound on q ν e is stronger than the bounds from the analyses of the data from TEXONO (jq ν e j < 1.0 × 10 −12 e at 90% C.L.) [41,[53][54][55] or GEMMA (jq ν e j < 1.5 × 10 −12 e at 90% C.L.) [19,56]. Regarding q ν μ=τ , the bound is more than one order of magnitude more stringent than that obtained from solar neutrinos by the XMASS Collaboration (jq ν μ=τ j < 1.1 × 10 −11 e at 90% C.L.) [57]. ...
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.
... Evaluation of the double differential cross sections of the ALP IP processes builds on our earlier work of incorporating the atomic many-body physics effects to low energy neutrino [29][30][31] and DM [32,33] interactions with matter, ...
Axionlike particles (ALPs) can be produced in the Sun and are considered viable candidates for the cosmological dark matter (DM). It can decay into two photons or interact with matter. We identify new inelastic channels of inverse Primakoff processes due to atomic excitation and ionization. Their cross sections are derived by incorporating full electromagnetic fields of atomic charge and current densities, and computed by well-benchmarked atomic many-body methods. Complementing data from the underground XENONnT and surface TEXONO experiments are analyzed. Event rates and sensitivity reaches are evaluated with respect to solar- and DM-ALPs. New parameter space in ALP couplings with the photons versus ALP masses in (1 eV–10 keV) not previously accessible to laboratory experiments are probed and excluded with solar-ALPs. However, at regions where DM-ALPs have already decayed, there would be no ALP-flux and hence, no interactions at the detectors in direct search experiments. No physics constraints can be derived. Future projects would be able to evade the stability bound and open new observable windows in (100 eV–1 MeV) for DM-ALPs.
... In Fig. 5(b) a collection of existing bounds coming from different experiments is shown. It can be seen that the limits derived in this work using the LZ data and the more realistic EPA formalism significantly improve the previous best laboratory limits, that for the electron neutrino electric charge was obtained in Ref. [55] by combining TEXONO [56] and GEMMA [57] data, finding jq ν e j < 1.0 × 10 −12 e 0 . We expect, however, that adopting the EPA or the RRPA formalism to analyse the XENONnT data would allow us to further constrain the limit on this fundamental quantity. ...
Elastic neutrino-electron scattering represents a powerful tool to investigate key neutrino properties. In view of the recent results released by the LUX-ZEPLIN collaboration, we provide a first determination of the limits achievable on the neutrino magnetic moment and neutrino millicharge, whose effect becomes non-negligible in some beyond the Standard Model theories. In this context, we evaluate and discuss the impact of different approximations to describe the neutrino interaction with atomic electrons. The new LUX-ZEPLIN data allows us to set a very competitive limit on the neutrino magnetic moment when compared to the other laboratory bounds, namely μνeff<1.1×10−11μB at 90% C.L., which improves by a factor of 2.5 the Borexino collaboration limit and represents the second best world limit after the recent XENONnT result. Moreover, exploiting the so-called equivalent photon approximation, we obtain the most stringent limit on the neutrino millicharge, namely |qνeff|<1.5×10−13e0 at 90% C.L., which represents a great improvement with respect to the previous laboratory bounds.
Next generation direct dark matter detection experiments are favorable facilities to probe neutrino properties and light mediators beyond the Standard Model. We explore the implications of the recent data reported by LUX-ZEPLIN (LZ) and XENONnT collaborations on electromagnetic neutrino interactions and neutrino generalized interactions (NGIs). We show that XENONnT places the most stringent upper limits on the effective and transition neutrino magnetic moment (of the order of few ×10−12μB) as well as stringent constraints to neutrino millicharge (of the order of ∼10−13e)–competitive to LZ–and improved by about one order of magnitude in comparison to existing constraints coming from Borexino and TEXONO. We furthermore explore the XENONnT and LZ sensitivities to simplified models with light NGIs and find improved constraints in comparison to those extracted from Borexino-Phase II data.
We derive new limits on the neutrino electromagnetic interactions and weakly coupled light vector and scalar mediators using the recent XENONnT data of the solar neutrino-electron elastic scattering. XENONnT has already reported the world's best constraint on the flavor-independent effective neutrino magnetic moment with almost twice the exposure and improved systematics. We extend this analysis and derive constraints on all the possible electromagnetic interactions and flavor universal light gauge boson couplings and masses, which could contribute to the neutrino-electron elastic scattering process. We consider both flavor-independent and flavor-dependent interactions of the neutrino magnetic moments, millicharges, charge radii, and anapole moments for the electromagnetic interactions. The new limits on the magnetic moment, millicharge, vector, and scalar interactions are improved by about one order of magnitude. At the same time, there is relatively weaker improvement in the case of neutrino charge radii and anapole moments.
We analyze new data from the COHERENT experiment of the coherent neutrino-nucleus scattering to investigate the electromagnetic interactions of neutrinos. With almost double the statistics and precision now, the statistical significance of the observed process has now enhanced to 11.6σ. We derive constraints on the electromagnetic properties of neutrinos using the new COHERENT data. The constraints improve by more than a factor of two compared to the previous bounds. Furthermore, we discuss the unique behavior of the neutrino millicharge at lower energy recoils and show its unique dependence on its interference with the standard model contribution, inverse power of recoil energy and the mass of the target particle in comparison to the other interactions.
A bstract
In this work, we explore new spin-1 states with axial couplings to the standard model fermions. We develop a data-driven method to estimate their hadronic decay rates based on data from τ decays and using SU(3) flavor symmetry. We derive the current and future experimental constraints for several benchmark models. Our framework is generic and can be used for models with arbitrary vectorial and axial couplings to quarks. We have made our calculations publicly available by incorporating them into the D ark C ast package, see https://gitlab.com/darkcast/releases .
A bstract
Neutrino-electron scattering experiments can explore the potential presence of a light gauge boson A′ which arises from an additional U(1) B−L group, or a dark photon A′ which arises from a dark sector and has kinetic mixing with the SM hypercharge gauge field. We generically call it a dark photon. In this study, we investigate the effect of the dark photon on neutrino-electron scattering νe − → νe − at the newly proposed forward physics experiments such as FASER ν , FASER ν 2, SND@LHC and FLArE(10 tons). We estimate the anticipated sensitivities to the U(1) B−L gauge coupling in a wide range of the dark photon mass M A ′ . We compare the sensitivities of the proposed forward physics experiments with the current limits from TEXONO, GEMMA, BOREXINO, LSND, and CHARM II as well as NA64e experiments. We also extend the calculation to obtain the sensitivities on the kinetic mixing parameter ϵ in a wide range of dark photon mass M A ′ . We demonstrate that the sensitivities do not improve for M A ′ < 1 GeV at the Forward Physics Facilities.
A bstract
We study future DUNE sensitivity to various electromagnetic couplings of neutrinos, including magnetic moments, milli-charges, and charge radii. The DUNE PRISM capabilities play a crucial role in constraining the electron flavored couplings. We find that DUNE will be able to place the strongest beam based constraint on the muon-neutrino magnetic moment by improving on LSND’s bounds by roughly a factor of two, although Borexino’s constraint from solar neutrinos will be stronger. For the muon neutrino millicharge DUNE can place the leading beam based bound, with two orders of magnitude improvement compared to the existing COHERENT constraint, suggesting that DUNE can be useful for light mediators more generally. Despite this strength, the millicharge bounds are not competitive with strong bounds from stellar cooling, beta-decay, and matter stability. Finally, DUNE may be able to test the SM prediction for the muon neutrino charge radius, by placing a constraint two times better than CHARM-II and CCFR experiments.
We review recent advances in the theoretical understanding of electric charge quantization in the Standard Model and some of its extensions. We discuss the roles played by classical constraints, gauge and mixed gauge-gravitational anomaly-cancellation and the demand of vector-like electromagnetic interactions. An attempt is made to clearly explain and contrast the points of view of various authors.
An ab initio calculation of atomic ionization of germanium by neutrinos was carried out in the framework of multiconfiguration relativistic random phase approximation and benchmarked by related atomic structure and photoabsorption data. This improves over the conventional approach based on scattering off free electrons whose validity at sub-keV energy transfer is questionable. Limits on neutrino magnetic moments are derived using reactor neutrino data taken with low threshold germanium detectors. Future applications of these atomic techniques will greatly reduce the atomic uncertainties in low-energy neutrino and dark matter detections.
The article describes the research program towards an experiment to
observe coherent scattering between neutrinos and the nucleus at the
power reactor. The motivations of studying this process are surveyed. In
particular, a threshold of 100-200 eV has been achieved with an
ultra-low-energy germanium detector prototype. This detection capability
at low energy can also be adapted to conduct searches of Cold Dark
Matter in the low-mass region as well as to enhance the sensitivities in
the study of neutrino magnetic moments.
The result of the neutrino magnetic moment measurement at the Kalinin Nuclear Power Plant (KNPP) with GEMMA spectrometer is presented. The antineutrino-electron scattering is investigated. A high-purity germanium detector with a mass of 1.5 kg placed at a distance of 13.9 m from the 3 GW th reactor core is exposed to the antineutrino flux of 2.7 × 10 13 1/cm2/s. The recoil electron spectra taken in 18134 and 4487 hours for the reactor ON and OFF periods are compared. The upper limit for the neutrino magnetic moment μ ν < 2.9 × 10 − 11 μ B at 90% C.L. is derived from the data processing.
This biennial Review summarizes much of particle physics. Using data from previous editions, plus 2658 new measurements from 644 papers, we list, evaluate, and average measured properties of gauge bosons, leptons, quarks, mesons, and baryons. We summarize searches for hypothetical particles such as Higgs bosons, heavy neutrinos, and supersymmetric particles. All the particle properties and search limits are listed in Summary Tables. We also give numerous tables, figures, formulae, and reviews of topics such as the Standard Model, particle detectors, probability, and statistics. Among the 112 reviews are many that are new or heavily revised including those on Heavy-Quark and Soft-Collinear Effective Theory, Neutrino Cross Section Measurements, Monte Carlo Event Generators, Lattice QCD, Heavy Quarkonium Spectroscopy, Top Quark, Dark Matter, Vcb & Vub, Quantum Chromodynamics, High-Energy Collider Parameters, Astrophysical Constants, Cosmological Parameters, and Dark Matter.A booklet is available containing the Summary Tables and abbreviated versions of some of the other sections of this full Review. All tables, listings, and reviews (and errata) are also available on the Particle Data Group website: http://pdg.lbl.gov/.The 2012 edition of Review of Particle Physics is published for the Particle Data Group as article 010001 in volume 86 of Physical Review D.This edition should be cited as: J. Beringer et al. (Particle Data Group), Phys. Rev. D 86, 010001 (2012).
DOI:https://doi.org/10.1103/PhysRevLett.106.059901
The energy spectra of electrons knocked out from atoms due to inelastic nue scattering are calculated within the electroweak minimal model, incorporating neutrino electromagnetic form factors. It is shown that these spectra differ significantly from the free scattering ones not only at incoming neutrino energies comparable with electron binding, but also at energies being an order of magnitude larger. For magnetic scattering, the cross sections on bound electrons are always less than on the free ones, and recoil electron spectra at low kinetic energies are naturally cut off. The role of these effects in the scattering of reactor nueis demonstrated.