Neutrino Dark Matter Research Articles

Cosmological Neutrino N-Body Simulations of Dark Matter Halo

The study of massive neutrinos and their interactions is a critical aspect of contemporary cosmology. Recent advances in parallel computation and high-performance computing provide new opportunities for accurately constraining Large-Scale Structures (LSS). In this paper, we introduce the TianNu cosmological N-body simulation during the co-evolution of massive neutrino and cold dark matter components via the CUBEP3M code running on the supercomputer Tianhe-2 and TianNu’s connected works. We start by analyzing 2.537×107 dark halos from the scientific data of TianNu simulation, and compare their angular momentum with the matched halos from neutrino-free TianZero, revealing a dependence of angular momentum modulus on neutrino injection at scales below 50 Mpc and around 10 Mpc.

Sterile neutrino dark matter: relativistic freeze-out

Long-lived sterile neutrinos can play the role of dark matter. We consider the possibility that such neutrinos form a thermal bath with a singlet scalar, while not being in thermal equilibrium with the Standard Model fields. Eventually, the neutrino dark matter undergoes freeze-out in the dark sector, which can occur in both non-relativistic and relativistic regimes. To account for the latter possibility, we use the full Fermi-Dirac and Bose-Einstein distribution functions with effective chemical potential in the reaction rate computation. This allows us to study the freeze-out process in detail and also obtain the necessary thermalization conditions. We find that relativistic freeze-out occurs in a relatively small part of the parameter space. In contrast to the standard weakly-interacting-massive-particle (WIMP) scenario, the allowed dark matter masses extend to 104 TeV without conflicting perturbativity.

New constraints on the dark matter-neutrino and dark matter-photon scattering cross sections from TXS 0506+056

The flux of high energy neutrinos and photons produced in a blazar could get attenuated when they propagate through the dark matter spike around the central black hole and the halo of the host galaxy. Using the observation by IceCube of a few high-energy neutrino events from TXS 0506+056, and their coincident gamma ray events, we obtain new constraints on the dark matter-neutrino and dark matter-photon scattering cross sections. Our constraints are orders of magnitude more stringent than those derived from considering the attenuation through the intergalactic medium and the Milky Way dark matter halo. When the cross-section increases with energy, our constraints are also stronger than those derived from the CMB and large-scale structure.

Preface

The tenth international symposium on “Large TPCs for low-energy rare event detection” was held in Paris from 15th to 17th of December 2021 at the Institute of Astroparticle physics of the University of Paris. The 2020 issue of this conference series was cancelled due to the Covid pandemic. The symposium was organized in a hybrid mode, which allowed about 40 people to attend in-person among a total of 131 registered participants. Very strict sanitary measures were taken to keep the meeting safe.As in previous events the program included neutrino physics, dark matter and axion searches, related detector R&D and theoretical aspects.To celebrate the tenth edition of the symposium the conference was held on three full days. Special speakers were invited to give a historical overview related to our field. David Nygren shared his memories of the invention and development of the Time Projection Chamber. François Vannucci revealed to us the invisible world of neutrinos. Ioannis Giomataris pointed out various innovative ideas that emerged during presentations and discussions in the last two decades. Jean Iliopoulos retraced the concept and development of the Standard Model and shared his personal vision on the future of particle physics.We wish to thank the many people who contributed to the success of the conference and especially the conveners of the sessions, who allowed for a smooth running of the meeting. We particularly acknowledge the APC management for providing the nice Buffon auditorium and infrastructure. We also thank DSM-Irfu, the University of Zaragoza, the European Research Council and ACAV Ile de France for their valuable support.The organizersList of Organizing Committee is available in this Pdf.

Gamma-ray energies and intensities observed in decay chain 83Rb/83mKr/83Kr

Radioactive sources of the monoenergetic low-energy conversion electrons from the decay of isomeric ^{83textrm{m}}mathrm {{Kr}} are frequently used in the systematic measurements, particularly in the neutrino mass and dark matter experiments. For this purpose, the isomer is obtained by the decay of its parent radionuclide ^{83}mathrm {{Rb}}. In order to get more precise data on the gamma-rays occuring in the ^{83}mathrm {{Rb}}/^{83textrm{m}}mathrm {{Kr}} chain, we re-measured the relevant gamma-ray spectra, because the previous measurement took place in 1976. The obtained intensities are in fair agreement with the previous measurement. We have, however, improved the uncertainties by a factor of 4.3, identified a new gamma transition and determined more precisely energies of weaker gamma transitions.

Neutrinoless double beta decay and sterile neutrino dark matter in extended left right symmetric model

Abstract We have studied a flavor symmetry-based extended left-right symmetric model(LRSM) with a dominant type-II seesaw mechanism and have explored the associated neutrino phenomenology. The particle content of the model includes usual quarks and leptons along with additional sterile fermion per generation in the fermion sector while the scalar content contains Higgs doublets and scalar bidoublet. This extension of LRSM has been realized by using $A_{4}\times Z_{4}$ discrete symmetries. In this work, we have included the study of sterile neutrino dark matter(DM) phenomenology and neutrinoless double beta decay within the framework.

Imprints of flavor anomalies on neutrino oscillations through dark matter halo

In this work we study the impact of new physics, stimulated by flavor anomalies, on neutrino oscillations through dense dark matter halo. Inspired by a model where a Majorana dark matter fermion and two new scalar fields contribute to b→sμ+μ− transition at the one loop level, we study the impact of neutrino-dark matter interaction on the oscillation patterns of ultra-high energy cosmic neutrinos passing through this muonphilic halo located near the center of Milky Way. We find that due to this interaction, the flavor ratios of neutrinos reaching earth would be different from that of vacuum oscillations. We also consider a Z′ model driven by Lμ−Lτ symmetry and containing a vector-like fermion as a dark matter candidate. It was previously shown that for such a model, the three flavors of neutrinos decouple from each other. This will render a flavor ratio similar to that of vacuum oscillations. Therefore, the interaction of neutrinos with dense dark matter halo can serve as an important tool to discriminate between flavor models with a dark connection.

Origin of neutrino masses, dark matter, leptogenesis, and inflation in a seesaw model with triplets

We consider a new physics model, where the Standard Model (SM) is extended by hyperchargeless $Y=0$ triplet fermions and a Higgs triplet with hypercharge $Y=2$. The first two generation fermion triplets are even under the ${Z}_{2}$ transformation. In contrast, the third fermion triplet and scalar triplet are odd under the same ${Z}_{2}$ transformation. It is a unifying framework for the simultaneous explanation of neutrino mass and mixing, dark matter, baryogenesis, inflation, and reheating temperature of the Universe. The two ${Z}_{2}$ even neutral fermions explain the neutrino low energy variables, whereas the third one can serve as a viable dark matter candidate, explaining the exact relic density. The scalar triplet is coupled nonminimally to gravity and forms the inflaton. We calculate the inflationary parameters and find them consistent with the new Planck-2018 constraints. We also do the reheating analysis for the inflaton decays/annihilations to relativistic SM particles. The triplet fermions associated with ${Z}_{2}$ even sector can provide the observed baryon asymmetry of the Universe at the TeV scale.

Generation of neutrino dark matter, baryon asymmetry, and radiation after quintessential inflation

We construct a model explaining dark matter, baryon asymmetry, and reheating in a quintessential inflation model. Three generations of right-handed neutrinos having hierarchical masses and the light scalar field leading to the self-interaction of active neutrinos are introduced. The lightest sterile neutrino is a dark matter candidate produced by a Dodelson-Widrow mechanism in the presence of a new light scalar field, while the heaviest and next-heaviest sterile neutrinos produced by gravitational particle production are responsible for the generation of the baryon asymmetry. Reheating is realized by spinodal instabilities of the Standard Model Higgs field induced by the nonminimal coupling to the scalar curvature, which can solve the overproduction of gravitons and curvature perturbation created by the Higgs condensation.

PBH-infused seesaw origin of matter and unique gravitational waves

The Standard Model, extended with three right-handed (RH) neutrinos, is the simplest model that can explain light neutrino masses, the baryon asymmetry of the Universe, and dark matter (DM). Models in which RH neutrinos are light are generally easier to test in experiments. In this work, we show that, even if the RH neutrinos are super-heavy (Mi=1,2,3> 109 GeV)—close to the Grand Unification scale—the model can be tested thanks to its distinct features on the stochastic Gravitational Wave (GW) background. We consider an early Universe filled with ultralight primordial black holes (PBH) that produce a super-heavy RH neutrino DM via Hawking radiation. The other pair of RH neutrinos generates the baryon asymmetry via thermal leptogenesis, much before the PBHs evaporate. GW interferometers can test this novel spectrum of masses thanks to the GWs induced by the PBH density fluctuations. In a more refined version, wherein a U(1) gauge symmetry breaking dynamically generates the seesaw scale, the PBHs also cause observable spectral distortions on the GWs from the U(1)-breaking cosmic strings. Thence, a low-frequency GW feature related to DM genesis and detectable with a pulsar-timing array must correspond to a mid- or high-frequency GW signature related to baryogenesis at interferometer scales.

HNL mass degeneracy: implications for low-scale seesaws, LNV at colliders and leptogenesis

Low-scale seesaw variants protected by lepton number symmetry provide a natural explanation of the smallness of neutrino masses but, unlike their higher-scale counterparts, with potentially testable phenomenology. The approximate lepton number symmetry arranges the heavy neutrinos in pseudo-Dirac pairs, which might be accessible at collider or even beam dump experiments if their mass is low enough and their mixing with the active neutrinos sufficiently large. Despite their pseudo-Dirac nature, their small mass splittings may lead to oscillations that prevent the cancellation of their potential lepton-number-violating signals. Interestingly, these small splittings may also resonantly enhance the production of a lepton number asymmetry for low-scale leptogenesis scenarios or, for extremely degenerate states, lead to an asymmetry large enough to resonantly produce a keV sterile neutrino dark matter candidate with the correct relic abundance via the Shi-Fuller mechanism. In this work we explore the parameter space of the different low-scale seesaw mechanisms and study the size of these splittings, given their important and interesting phenomenological consequences. While all low-scale seesaw variants share the same dimension 5 and 6 operators when integrating out the heavy states, we point out that the mass splitting of the pseudo-Dirac pairs are very different in different realizations such as the inverse or linear seesaw. This different phenomenology could offer a way to discriminate between low-scale seesaw realizations.

Probing dark matter interactions with 21cm observations

Similarly to warm dark matter which features a cut-off in the matter power spectrum due to free-streaming, many interacting dark matter models predict a suppression of the matter power spectrum on small length scales through collisional damping. Forecasts for 21cm line intensity mapping have shown that an instrument like the SKA will be able to probe a suppression of power in warm dark matter scenarios in a statistically significant way. Here we investigate the implications of these findings on interacting dark matter scenarios, particularly dark matter-neutrino interactions, which we use as an example. Using a suite of cosmological N-body simulations, we demonstrate that interacting scenarios show a suppression of the non-linear power spectrum similar to warm dark matter models. This implies that 21cm line intensity mapping will be able to set the strongest limits yet on dark matter-neutrino scattering, improving the constraints by two orders of magnitude over current Lyman-α bounds, and by four orders of magnitude over cosmic microwave background and baryon acoustic oscillations limits. However, to distinguish between warm dark matter and interacting scenarios, our simulations show that percent-level precision measurements of the matter power spectrum at redshifts z ≳ 15 are necessary, as the key features of interacting scenarios are washed out by non-linear evolution at later times.

Correlation analysis of decaying sterile neutrino dark matter in the context of the SRG mission

We provide a correlation analysis of signatures associated with traces of the dark matter decay and the galaxy spatial distribution according to the 2MRS catalog of galaxies. Signature data analysis plays an important role in the context of current and future observations and cosmological constraints. Attention is paid to the constraints that can be obtained for decaying sterile neutrinos when analyzing observations in the context of the Spectr-Roentegn-Gamma (SRG) mission. We study the correlation spectra of dark matter and galaxies, which can be obtained both for the eROSITA telescope and for the first time for the ART-XC telescope. The analysis is carried out both within the framework of the Limber approximation and within the framework of the extended Limber approximation, which makes it possible to more accurately study the power spectra in the region of small multipoles. We calculate the power spectra in both approaches and examine the contribution of different ranges of multipoles to the resulting constraints on sterile neutrino parameters.

Neutrino physics and dark matter search with SHiP at CERN

SHiP (Search for Hidden Particles) is a new general purpose fixed target facility, proposed at the CERN SPS accelerator. In its initial phase the 400 GeV protons beam will be dumped on a heavy target with the aim of integrating [Formula: see text] pot in five years. A dedicated detector downstream the target will allow to probe a variety of models with the light long-lived exotic particles and masses below O(10) GeV/c2. The beam dump is also a copious source of neutrinos and in particular it is an ideal source of tau neutrinos, the less known particle in the Standard Model. We report the physics potential of such an experiment. We also describe an ancillary measurement of the charm cross-section carried out in July 2018.

Unraveling the Scotogenic model at muon collider

The Scotogenic model extends the standard model with three singlet fermion Ni and one inert doublet scalar η to address the common origin of tiny neutrino mass and dark matter. For fermion dark matter N1, a hierarchical Yukawa structure mid {y}_{1e}mid ll mid {y}_{1mu}mid sim mid {y}_{1tau}mid sim mathcal{O}(1) is usually favored to satisfy constraints from lepton flavor violation and relic density. Such large μ-related Yukawa coupling would greatly enhance the pair production of charged scalar η± at the muon collider. In this paper, we investigate the dilepton and mono-photon signature of the Scotogenic model at a 14 TeV muon collider. For the dimuon signature , we find that most viable samples can be probed with 200 fb−1 data. The ditau signature is usually less promising, but it is important to probe the small |y1μ| region. The mono-photon signature could also probe the compressed mass region M1 ≲ {M}_{eta^{pm }} . Masses of charged scalar η± and dark matter N1 can be further extracted by a binned likelihood fit of the dilepton energy.

Constraining Sterile Neutrino Dark Matter in the Milky Way Halo with Swift-XRT

We present a search for sterile neutrino dark matter decay signals in the Milky Way’s dark matter halo by considering the entirety of the Swift X-ray Telescope (Swift-XRT) data archive. After filtering the raw archive, we analyze a ∼77 Ms data set containing the full field of view, as well as a ∼41 Ms data set with point sources excised using the Swift-XRT Point Source catalog. We report nondetections of emission lines across the 3–6 keV continuum in both data sets, including at and around 3.5 keV. The point-source-excised data set is found to have higher sensitivity to faint dark matter decay signals due to its freedom from point-source contamination and is thus used to set constraints. Nondetections across the total data set’s continuum are used to constrain the sterile neutrino dark matter parameter space, marginally strengthening existing X-ray constraints. Nondetections at ∼3.5 keV in data subsets grouped by angular distance from the galactic center are used to constrain the 3.5 keV line’s galactic intensity profile, providing the strongest constraints to date across ∼1/4 of the galaxy.

WIMP and FIMP dark matter in singlet-triplet fermionic model

We present an extension of the SM involving three triplet fermions, one triplet scalar and one singlet fermion, which can explain both neutrino masses and dark matter. One triplet of fermions and the singlet are odd under a Z2 symmetry, thus the model features two possible dark matter candidates. The two remaining Z2-even triplet fermions can reproduce the neutrino masses and oscillation parameters consistent with observations. We consider the case where the singlet has feeble couplings while the triplet is weakly interacting and investigate the different possibilities for reproducing the observed dark matter relic density. This includes production of the triplet WIMP from freeze-out and from decay of the singlet as well as freeze-in production of the singlet from decay of particles that belong to the thermal bath or are thermally decoupled. While freeze-in production is usually dominated by decay processes, we also show cases where the annihilation of bath particles give substantial contribution to the final relic density. This occurs when the new scalars are below the TeV scale, thus in the reach of the LHC. The next-to-lightest odd particle can be long-lived and can alter the successful BBN predictions for the abundance of light elements, these constraints are relevant in both the scenarios where the singlet or the triplet are the long-lived particle. In the case where the triplet is the DM, the model is subject to constraints from ongoing direct, indirect and collider experiments. When the singlet is the DM, the triplet which is the next-to-lightest odd particle can be long-lived and can be probed at the proposed MATHUSLA detector. Finally we also address the detection prospects of triplet fermions and scalars at the LHC.

Revisiting sterile neutrino dark matter in gauged U(1)B−L model

We reexamine sterile neutrino dark matter in gauged $U(1)_{B-L}$ model. Improvements have been made by tracing and careful evaluation of the evolution of the number densities of sterile neutrinos $N$ and extra neutral gauge bosons $Z'$. As a result, the cosmologically-interesting gauge coupling of $U(1)_{B-L}$ for freeze-in sterile neutrinos turns out to be smaller than the values reported in the literature. This avoids the overproduction of $Z'$ so that it is consistent with the big bang nucleosynthesis and the cosmic microwave background constraints on the effective number of neutrino species. Similarly, the free-streaming length constraints exclude a large parameter space derived in previous studies. In addition to known freeze-in pair production of $N$ from the standard model fermion pairs, we find the case that $N$ is dominantly produced from a pair of $Z'$ at the temperature characterized by the $B-L$ breaking scalar mass. Thus, the naive truncation of the $U(1)_{B-L}$ scalar contribution made in the literature is not valid.

Flavour anomalies and dark matter assisted unification in SO(10) GUT

With the recent experimental hint of new physics from flavor physics anomalies, combined with the evidence from neutrino masses and dark matter, we consider a minimal extension of SM with a scalar leptoquark and a fermion triplet. The scalar leptoquark with couplings to leptons and quarks can explain lepton flavor non-universality observables RK, {R}_{K^{left(ast right)}} , {R}_{D^{left(ast right)}} and RJ/ψ. Neutral component of fermion triplet provides current abundance of dark matter in the Universe. The interesting feature of the proposal is that the minimal addition of these phenomenologically rich particles (scalar leptoquark and fermion triplet) assist in realizing the unification of the gauge couplings associated with the strong and electroweak forces of standard model when embedded in the non-supersymmetric SO(10) grand unified theory. We discuss on unification mass scale and the corresponding proton decay constraints while taking into account the GUT threshold corrections.

Absolute neutrino mass scale and dark matter stability from flavour symmetry

We explore a simple but extremely predictive extension of the scotogenic model. We promote the scotogenic symmetry ℤ2 to the flavour non-Abelian symmetry Σ(81), which can also automatically protect dark matter stability. In addition, Σ(81) leads to striking predictions in the lepton sector: only Inverted Ordering is realised, the absolute neutrino mass scale is predicted to be mlightest≈ 7.5×10−4 eV and the Majorana phases are correlated in such a way that |mee| ≈ 0.018 eV. The model also leads to a strong correlation between the solar mixing angle θ12 and δCP, which may be falsified by the next generation of neutrino oscillation experiments. The setup is minimal in the sense that no additional symmetries or flavons are required.