Search

Electroweak scattering of neutrinos with hadronic targets reveal the underlying structure of protons and neutrons. Electroweak structure functions for nucleon targets are reviewed in the context of muon and tau neutrino and antineutrino scattering. Quantum chromodynamic, target mass and quark mass corrections and the regimes where they are relevant are discussed. In future experiments in the Large Hadron Collider forward region at CERN, there are prospects for future measurements for neutrino and antineutrino energies in the 100’s of GeV to TeV energy regime with a large flux of $$\nu _\tau +\overline{\nu }_\tau $$ as well as the electron and muon flavors. At lower energies, DUNE will probe structure functions at the boundary of perturbative and nonperturbative regimes.

The OPERA experiment was designed to discover the vτ appearance in a vμ beam, due to neutrino oscillations. The detector, located in the underground Gran Sasso Laboratory, consisted of a nuclear photographic emulsion/lead target with a mass of about 1.25 kt, complemented by electronic detectors. It was exposed from 2008 to 2012 to the CNGS beam: an almost pure vμ beam with a baseline of 730 km, collecting a total of 1.8·1020 protons on target. The OPERA Collaboration eventually assessed the discovery of vμ→vτ oscillations with a statistical significance of 6.1 σ by observing ten vτ CC interaction candidates. These events have been published on the Open Data Portal at CERN. This paper provides a detailed description of the vτ data sample to make it usable by the whole community., Measurement(s)tau neutrinoTechnology Type(s)detectorSample Characteristic - Environmentneutrino beamSample Characteristic - LocationLaboratori Nazionali del Gran Sasso Machine-accessible metadata file describing the reported data: 10.6084/m9.figshare.14979858

For clarifying the validity of the Lepton Universality hypothesis, one of the fundamental statements of the Standard Model, the interaction cross section for all three flavors of leptons have to be known with high precision. In neutrino sector, for electron and muon neutrinos, the interaction cross section is known fairly well, but for tau neutrino only poor estimations exist. In particular, the most direct measurement by the DONuT experiment was performed with rather poor accuracy due to low statistics and an uncertainty of the tau neutrino flux. The DsTau experiment proposes to study tau-neutrino production process and thus to improve significantly the accuracy of calculations of tau neutrino flux for neutrino accelerator experiments. To study reactions providing most of tau neutrinos, the experiment uses a setup based on high resolution nuclear emulsions, capable to register short lived particle decays created in proton-nucleus interactions. The present report is an overview of the DsTau experiment together with some of the preliminary results from the pilot run.

37. International Cosmic Ray Conference, ICRC 2021, Berlin, Germany, 15 Jul 2021 - 22 Jul 2021; Proceedings of Science 395, 1146 (2022). doi:10.22323/1.395.1146 special issue: "37th International Cosmic Ray Conference : ICRC2021 : 12-23 July 2021 : Berlin, Germany - Online / Editorial Board: Alexander Kappes, Institut für Kernphysik, Westfälische Wilhelms-Universität Münster, D-48149 Münster, Germany ; Bianca Keilhauer, Karlsruhe Institute of Technology, Institute for Astroparticle Physics (IAP)", Published by SISSA, Trieste

An accurate modeling of neutrino flux attenuation and the distribution of leptons they produce in transit through the Earth is an essential component to determine neutrino flux sensitivities of underground, sub-orbital and space-based detectors. Through neutrino oscillations over cosmic distances, astrophysical neutrino sources are expected to produce nearly equal fluxes of electron, muon and tau neutrinos. Of particular interest are tau neutrinos that interact in the Earth at modest slant depths to produce $\tau$-leptons. Some $\tau$-leptons emerge from the Earth and decay in the atmosphere to produce extensive air showers. Future balloon-borne and satellite-based optical Cherenkov neutrino telescopes will be sensitive to upward air showers from tau neutrino induced $\tau$-lepton decays. We present nuPyProp, a python code that is part of the nuSpaceSim package. nuPyProp generates look-up tables for exit probabilities and energy distributions for $\nu_\tau\to \tau$ and $\nu_\mu\to \mu$ propagation in the Earth. This flexible code runs with either stochastic or continuous electromagnetic energy losses for the lepton transit through the Earth. Current neutrino cross section models and energy loss models are included along with templates for user input of other models. Results from nuPyProp are compared with other recent simulation packages for neutrino and charged lepton propagation. Sources of modeling uncertainties are described and quantified., Comment: 9 pages, 6 figures, PoS(ICRC2021)1203; for associated code, see https://github.com/NuSpaceSim/nupyprop

We present the results of a simulation of the acceptance of the Antarctic Impulsive Transient Antenna (ANITA) to possible $\nu_\tau$ point source fluxes detected via $\tau$-lepton-induced air showers. This investigation is framed around the detection of four upward-going extensive air shower events observed very close to the horizon in ANITA-IV. These four events as well as the overall diffuse and point source exposure to Earth-skimming $\nu_\tau$ are also compared against published ultrahigh-energy neutrino limits from the Pierre Auger Observatory. We find that while these four events were detected at sky coordinates close to ANITA's maximum $\nu_\tau$ sensitivity and were not simultaneously visible by Auger, the implied fluence necessary for ANITA to observe these events is in tension with limits set by Auger across a wide range of energies and is additionally in tension with ANITA's Askaryan in-ice neutrino channel above~$10^{19}$~eV.

The hunt for cosmogenic neutrinos is a target of next generation observatories: IceCube-Gen2, RNO, GRAND, POEMMA, and CHANT. In a recent publication, a novel detection strategy for these neutrinos has been put forward. This new technique relies on the observation of Earth-throughgoing tau neutrinos at PeV energies. By measuring the flux at this energy, we can indirectly observe the flux at EeV energies since these two are related by the cascading down of the neutrinos. However, such a link demands an accurate simulation of the VHE tau neutrino transport. TauRunner is a Python Monte Carlo (MC) package developed in 2019 that was intended for such effort, but contained some limitations. This contribution will present the newest version of this MC, which now incorporates all the neutrino flavors in the propagation as well as other features.

The Beamforming Elevated Array for COsmic Neutrinos (BEACON) is a concept for a neutrino telescope designed to measure tau lepton air showers generated from tau neutrino interactions near the horizon. This detection mechanism provides a pure measurement of the tau flavor of cosmogenic neutrinos, which could be used to set limits on the observed flavor ratios for cosmogenic neutrinos in a manner complimentary to the all-flavor neutrino flux measurements made by other experiments. BEACON is expected to also be capable of detecting cosmic rays through RF-only triggers. BEACON aims to achieve this sensitivity by using mountaintop radio arrays of dual-polarized antennas operating in the 30-80 MHz band which utilize directional interferometric triggering. BEACON stations are designed to efficiently use a small amount of instrumentation, allowing for deployment in a variety of high-elevation sites. The interferometric trigger provides a natural tool for directional-based anthropogenic RFI rejection at the trigger level, broadening the list for potential station sites. The BEACON prototype has seen continuous design advancements towards improving the mechanical durability and scientific capabilities since its initial deployment at White Mountain Research Station in 2018. Here we present the current prototype’s sensitivity to RF-triggered cosmic-ray background signals. We also present the next generation prototype, which includes scintillating cosmic ray detectors, improved antennas, and refined calibration techniques.

The description of the heavy meson production at large energies and forward rapidities at the LHC is fundamental to derive realistic predictions of the prompt atmospheric neutrino flux at the IceCube Observatory. In particular, the prompt tau neutrino flux is determined by the decay of D s mesons produced in cosmic ray–air interactions at high energies and large values of the Feynman- x F variable. Recent data of the LHCb Collaboration indicate a production asymmetry for D s + and D s − mesons, which cannot be explained in terms of the standard modeling of the hadronization process. In this paper we demonstrate that this asymmetry can be described assuming an asymmetric strange sea ( s ( x ) ≠ s ¯ ( x ) ) in the proton wave function and taking into account the dominant charm and subdominant strange fragmentation into D s mesons. Moreover, we show that the strange quark fragmentation contribution is dominant at large- x F (≥0.3). The prompt ν τ flux is calculated and the enhancement associated with the strange quark fragmentation contribution, disregarded in previous calculations, is estimated. The considered scenario leads to quite sizable enhancement of the high-energy τ-neutrino flux.

SHiP is a proposed general purpose fixed target experiment to be located at the CERN SPS accelerator. A fixed target station will be followed by magnetic shielding to reduce beam induced background, a dedicated tau neutrino detector and a detector to search for hidden particles beyond the Standard Model. Background taggers and a dedicated timing detector will ensure sufficient background rejection. The timing detector is required to have a timing resolution of 100 ps or less in order to reduce combinatorial di-muon background to an acceptable level. A proposed option for such a timing detector consists of plastic scintillating bars read out on each end by silicon photomultipliers, which is the focus of this study. We report on recent testbeam results carried out at CERN on single bars read out by an array of silicon photomultipliers and present a design for a prototype of the SHiP timing detector.

The SHiP experiment (for Search for Hidden Particles) which will operate at the CERN Super Proton Synchrotron (SPS) is one of the most promising projects in the field of particle physics. The SPS 400-GeV/c proton beam will be dumped onto the molybdenum–tungsten target of the SHiP detector, and the data corresponding to 2 × 1020 protons on the target will be accumulated in five years of running. The experiment is aimed at a search for very weakly interacting neutral particles beyond the Standard Model framework referred to as novel physics particles: massive neutral leptons, axions, and “dark” photons. Possible existence of such particles can help explain such firmly established phenomena as the baryon asymmetry of the Universe, nonzero neutrino masses, and the presence of dark matter. Beyond that, the experimental program envisages extensive studies in neutrino physics. In particular, we aim at directly detecting the tau antineutrino—the only Standard Model particle which until now has escaped experimental detection. The envisaged search for the right-handed neutrino partners is particularly interesting: theoretically, their existence can help explain some observed phenomena not predicted by the Standard Model. Experimental investigations in the fields of tau-neutrino interactions (as the least studied sector of neutrino physics) and production of charmed particles and a search for interactions of particles of light dark matter will be carried out with a neutrino detector based on relativistic nuclear emulsion. The τ- and τ+ production events will be discriminated (whereby the production of tau antineutrinos will be directly detected) using special magnets developed for the SHiP emulsion detector. Presently, a prototype of the emulsion detector as a key element of the SHiP neutrino detector is being simulated, constructed, and tested. The nuclear-emulsion technology provides a record-high spatial resolution as required for detecting charged particles with extremely short lifetimes. The nuclear-emulsion data will be processed with the advanced automatic equipment available at the participating laboratories. Efficient scanning of large areas on nuclear emulsion relies on modern scanning equipment such as the PAVICOM measuring complex developed at the Lebedev Physical Institute. Thereby, one can efficiently process the data collected with any track detectors, including those irradiated by accelerator beams. On the whole, the construction of the SHiP detector poses a number of nontrivial physical and technical problems addressed by physicists from 62 laboratories operating in 16 countries.

We present a detailed modeling and computation methodology to determine the optical Cherenkov signals produced by upward-moving extensive air showers (EASs) induced by $\ensuremath{\tau}$-leptons and muons, sourced from the interaction of high-energy astrophysical neutrinos interacting in the Earth. Following and extending the physics modeling and Cherenkov signal simulations performed in M. H. Reno et al. [Phys. Rev. D 100, 063010 (2019)], this scheme encompasses a new, state-of-the-art computation of the muon neutrino propagation inside the Earth and the contribution to the $\ensuremath{\tau}$-lepton muon decay channel. The modeling takes into account all possible $\ensuremath{\tau}$-lepton decay and muon energy loss channels that feed the optical Cherenkov emission, produced by both tau and muon initiated EASs. The EAS modeling uses the electron energy, angular, and lateral distributions in the EAS and their evolution as well as the wavelength dependence of the Cherenkov emission and its atmospheric attenuation. The results presented here are focused on the detection capabilities of suborbital (balloon-borne) and orbital (satellite) based instruments. The latter case was calculated for POEMMA [The Probe Of Extreme MultiMessenger Astrophysics] to compare to that presented in M. H. Reno et al. [Phys. Rev. D 100, 063010 (2019)], specifically including the muon-decay channel of $\ensuremath{\tau}$-leptons and the muonic EAS Cherenkov signal from muon neutrino interactions in the Earth. By detailing all these individual contributions to the optical Cherenkov emission and detection, we show how the ensemble that includes muonic channels provides a large detection capability for space-based, high-energy cosmic neutrino detection. Specifically, we show that for neutrino energies $\ensuremath{\lesssim}10\text{ }\text{ }\mathrm{PeV}$, the upward-EAS sensitivity due to muon neutrino interactions in the Earth begin to dominate over that for tau neutrino interactions, effectively extending the neutrino sensitivity to lower energies.

DsTau (NA65) at the CERN-SPS is a recently approved experiment, which aims to study the tau neutrino production in proton-nuclei interaction. The main source of tau neutrinos is the decay of Ds mesons, namely Ds → τντ and then τ → ντX. There is almost no data on the differential production cross section of Ds in proton-nucleus interactions, which leads to a large uncertainty of tau neutrino interaction cross section measurements preventing a precise test of Lepton Flavour Universality in neutrino scattering. DsTau addresses this issue and will provide essential inputs for future tau neutrino experiments. A large amount of charmed particles decay events (~105) is expected to be detected as well, providing a possibility for interesting by-product studies, in particular a search for intrinsic charm in a proton. The experimental method is based on a use of high resolution emulsion detectors for effective registration of events with short lived particle decays. Here I present the motivation of the study, details of the experimental technique and the possible improvement that BDT method can provide for the signal/background events separation.

The goal of the DsTau (NA65) experiment at CERN SPS is the measurement of tau neutrino production. The dominant source of tau neutrinos is decay of $D_s$ mesons, produced in proton-nucleon interactions, to tau neutrino and tau lepton with further decay of tau lepton. Thus, the experiment aims to measure differential cross section of this reaction. This measurement will allow to re-evaluate DONuT results reducing the systematic error in tau neutrino interaction cross section caused by the tau neutrino flux uncertainty in beam dump experiments from 50\% to 10\%. Such accuracy of cross section measurement will allow testing the Lepton Flavour Universality for neutrinos. The experiment exploits nuclear emulsion detectors with $\mu$m space resolution allowing to recognize the peculiar $D_s$ to $\tau$ decay topology in a few mm range. In addition, about $10^5$ charmed particle decays are expected in the experiment, which makes possible to study charm physics, in particular to search for intrinsic charm component in proton. About 10\% of whole data were collected during 2018 pilot run and analysis of this sample is ongoing. Given the relevance of the study and encouraging results of the data analysis, CERN had approved the DsTau project as a new experiment NA65 in 2019. The main data sample will be collected in 2021-22 physics runs. In this paper, the status and prospects of NA65 as well as the results of the pilot run are presented.

An event topology with two secondary vertices compatible with the decay of short-lived particles was found in the analysis of neutrino interactions in the OPERA target. The observed topology is compatible with tau neutrino charged current (CC) interactions with charm production and neutrino neutral current (NC) interactions with $$c\overline{c}$$cc¯ pair production. However, other processes can mimic this topology. A dedicated analysis was implemented to identify the underlying process. A Monte Carlo simulation was developed and complementary procedures were introduced in the kinematic reconstruction. A multivariate analysis technique was used to achieve an optimal separation of signal from background. Most likely, this event is a $$\nu _{\tau }$$ντ CC interaction with charm production, the tau and charm particle decaying into 1 prong and 2 prongs, respectively. The significance of this observation is evaluated.

We investigate tau neutrinos from heavy flavor hadrons that can be explored at a high rapidity LHC experiment. A large number of tau neutrinos can be produced in $pp$ collision at the LHC in the very forward region, where its main source is $D_s^\pm$ mesons since the weak boson contribution is negligible. Abundant production of tau neutrinos will allow the precise study of tau neutrino charged current interactions to test lepton universality. In addition, it will provide the opportunity to probe the mixing between sterile neutrinos and tau neutrinos. We evaluate the fluxes and the event rates of the prompt tau neutrinos as well as the theoretical uncertainty using fits to the experimental data for charm meson production. Also, we describe the sterile neutrino masses and mixing angles that can be constrained by tau neutrinos from the LHC.

The SHiP Collaboration has proposed a general-purpose experimental facility operating in beam dump mode at the CERN SPS accelerator with the aim of searching for light, long-lived exotic particles of Hidden Sector models. The SHiP experiment incorporates a muon shield based on magnetic sweeping and two complementary apparatuses. The detector immediately downstream of the muon shield is optimised both for recoil signatures of light dark matter scattering and for tau neutrino physics, and consists of a spectrometer magnet housing a layered detector system with heavy target plates, emulsion film technology and electronic high precision tracking. The second detector system aims at measuring the visible decays of hidden sector particles to both fully reconstructible final states and to partially reconstructible final states with neutrinos, in a nearly background free environment. The detector consists of a 50 m long decay volume under vacuum followed by a spectrometer and particle identification with a rectangular acceptance of 5 m in width and 12 m in height. Using the high-intensity beam of 400 GeV protons, the experiment is capable of integrating $2\times10^{20}$ protons in five years, which allows probing dark photons, dark scalars and pseudo-scalars, and heavy neutrinos with GeV-scale masses at sensitivities that exceed those of existing and projected experiments. The sensitivity to heavy neutrinos will allow for the first time to probe, in the mass range between the kaon and the charm meson mass, a coupling range for which baryogenesis and active neutrino masses can be explained. The sensitivity to light dark matter reaches well below the elastic scalar dark matter relic density limits in the range from a few MeV/c$^{2}$ up to 200 MeV/c$^{2}$. The tau neutrino deep-inelastic scattering cross-sections will be measured with a statistics a thousand times larger than currently available data, with the extraction of the F4 and F5 structure functions, never measured so far, and allow for new tests of lepton non-universality with sensitivity to BSM physics. Following the review of the Technical Proposal, the CERN SPS Committee recommended in 2016 that the experiment and the beam dump facility studies proceed to a Comprehensive Design Study phase. These studies have resulted in a mature proposal submitted to the European Strategy for Particle Physics Update.

The SHiP Collaboration has proposed a general-purpose experimental facility operating in beam dump mode at the CERN SPS accelerator with the aim of searching for light, long-lived exotic particles of Hidden Sector models. The SHiP experiment incorporates a muon shield based on magnetic sweeping and two complementary apparatuses. The detector immediately downstream of the muon shield is optimized both for recoil signatures of light dark matter scattering and for tau neutrino physics. The second detector system aims at measuring the decays of hidden sector particles into the visible sector in a nearly background free environment. The detector consists of a 50 m long decay volume followed by a spectrometer and particle identification. Using the high-intensity beam of 400 GeV protons, the experiment is capable of integrating $2\times10^{20}$ protons in five years, which allows probing dark photons, dark scalars and pseudo-scalars, and heavy neutrinos with GeV-scale masses at unprecedented sensitivities. The sensitivity to heavy neutrinos will allow for the first time to probe, in the mass range between the kaon and the charm meson mass, a coupling range for which baryogenesis and active neutrino masses can be explained. Following the review of the Technical Proposal, the CERN SPS Committee recommended in 2016 that the experiment and the beam dump facility studies proceed to a Comprehensive Design Study phase. These studies have resulted in a mature proposal submitted to the European Strategy for Particle Physics Update.

The tau neutrino is one of the least studied particle in the Standard Model. Current tau neutrino-nucleon cross section measurement suffer large $\sim 30\%$ statistical and $\sim 50\%$ systematic uncertainties. In near future statistical uncertainty will be reduced to a few \% by the SHiP experiment, or by the experiments such as SHiP. DsTau (NA65) experiment at CERN aims to reduce the systematic uncertainty on tau neutrino-nucleon cross section through investigating a precise measurement on tau neutrino production, $Ds\rightarrow\tau+\nu_{\tau}$ differential production cross section with tungsten target. The uncertainty of the tau neutrino flux will be reduced to 10 \% from 50\%. Collaboration will collect $2.3\times10^{8}$ proton interactions with tungsten target and study about $10^5$ charm associated interactions. A pilot run was performed in 2018 Aug and collecting about a tenth of final statistics to perform full analysis chain. Here the analysis stream and the analysis status of 2018 Aug pilot run will be described.

The tau neutrino is probably the least studied particle in the SM, with only a handful of interaction events being identified so far. This can in part be attributed to their small production rate in the SM, which occurs mainly through D_s meson decay. However, this also makes the tau neutrino flux measurement an interesting laboratory for additional new physics production modes. In this study, we investigate the possibility of tau neutrino production in the decay of light vector bosons. We consider four scenarios of anomaly-free U(1) gauge groups corresponding to the B-L, B-L_mu-2L_tau, B-L_e-2L_tau and B-3L_tau numbers, analyze current constraints on their parameter spaces and explore the sensitivity of DONuT and as well as the future emulsion detector experiments FASERnu, SND@LHC an SND@SHiP. We find that these experiments provide the leading direct constraints in parts of the parameter space, especially when the vector boson's mass is close to the mass of the omega meson., 10 pages, 2 figures, updated version as published in PRD

The ANITA balloon experiment was designed to detect radio signals initiated by neutrinos and cosmic ray air showers. These signals are typically discriminated by the polarization and phase inversions of the radio signal. The reflected signal from cosmic rays suffer phase inversion compared to a direct tau neutrino event. In this paper we study sub-surface reflection, which can occur without phase inversion, in the context of the two anomalous up-going events reported by ANITA. We find that subsurface layers and firn density inversions may plausibly account for the events, while ice fabric layers and wind ablation crusts could also play a role. This hypothesis can be tested with radar surveying of the Antarctic region in the vicinity of the anomalous ANITA events. Future experiments should not use phase inversion as a sole criterion to discriminate between downgoing and upgoing events, unless the subsurface reflection properties are well understood., 4+2 pages, 3 figures

We present a new calculation of the energy distribution of high-energy neutrinos from the decay of charm and bottom hadrons produced at the Large Hadron Collider (LHC). In the kinematical region of very forward rapidities, heavy-flavor production and decay is a source of tau neutrinos that leads to thousands of { charged-current} tau neutrino events in a 1 m long, 1 m radius lead neutrino detector at a distance of 480 m from the interaction region. In our computation, next-to-leading order QCD radiative corrections are accounted for in the production cross-sections. Non-perturbative intrinsic-$k_T$ effects are approximated by a simple phenomenological model introducing a Gaussian $k_T$-smearing of the parton distribution functions, which might also mimic perturbative effects due to multiple initial-state soft-gluon emissions. The transition from partonic to hadronic states is described by phenomenological fragmentation functions. To study the effect of various input parameters, theoretical predictions for $D_s^\pm$ production are compared with LHCb data on double-differential cross-sections in transverse momentum and rapidity. The uncertainties related to the choice of the input parameter values, ultimately affecting the predictions of the tau neutrino event distributions, are discussed. We consider a 3+1 neutrino mixing scenario to illustrate the potential for a neutrino experiment to constrain the 3+1 parameter space using tau neutrinos and antineutrinos. We find large theoretical uncertainties in the predictions of the neutrino fluxes in the far-forward region. Untangling the effects of tau neutrino oscillations into sterile neutrinos and distinguishing a 3+1 scenario from the standard scenario with three active neutrino flavours, will be challenging due to the large theoretical uncertainties from QCD., 39 pages, 16 figures

In the DsTau experiment at the CERN SPS (NA65), an independent and direct way to measure tau neutrino production following high energy proton interactions was proposed. As the main source of tau neutrinos is a decay of D$_{s}$ mesons, produced in proton-nucleus interactions, the project aims at measuring a differential cross section of this reaction. The experimental method is based on a use of high resolution emulsion detectors for effective registration of events with short lived particle decays. Here we present the motivation of the study, details of the experimental technique, and the first results of the analysis of the data collected during test runs, which prove feasibility of the full scale study of the process in future. In the DsTau experiment at the CERN SPS, an independent and direct way to measure tau neutrino production following high energy proton interactions was proposed. As the main source of tau neutrinos is a decay of Ds mesons, produced in proton-nucleus interactions, the project aims at measuring a differential cross section of this reaction. The experimental method is based on a use of high resolution emulsion detectors for effective registration of events with short lived particle decays. Here we present the motivation of the study, details of the experimental technique, and the first results of the analysis of the data collected during test runs, which prove feasibility of the full scale study of the process in future.

We report on the first measurement of the astrophysical neutrino flux using particle showers (cascades) in IceCube data from 2010-2015. Assuming standard oscillations, the astrophysical neutrinos in this dedicated cascade sample are dominated (∼90%) by electron and tau flavors. The flux, observed in the sensitive energy range from 16 TeV to 2.6 PeV, is consistent with a single power-law model as expected from Fermi-type acceleration of high energy particles at astrophysical sources. We find the flux spectral index to be γ=2.53±0.07 and a flux normalization for each neutrino flavor of φastro=1.66-0.27+0.25 at E0=100 TeV, in agreement with IceCube's complementary muon neutrino results and with all-neutrino flavor fit results. In the measured energy range we reject spectral indices γ≤2.28 at ≥3σ significance level. Because of high neutrino energy resolution and low atmospheric neutrino backgrounds, this analysis provides the most detailed characterization of the neutrino flux at energies below ∼100 TeV compared to previous IceCube results. Results from fits assuming more complex neutrino flux models suggest a flux softening at high energies and a flux hardening at low energies (p value ≥0.06). The sizable and smooth flux measured below ∼100 TeV remains a puzzle. In order to not violate the isotropic diffuse gamma-ray background as measured by the Fermi Large Area Telescope, it suggests the existence of astrophysical neutrino sources characterized by dense environments which are opaque to gamma rays., SCOPUS: ar.j, info:eu-repo/semantics/published

We calculate the signal rate of hypothetical heavy neutral leptons (HNL or sterile neutrinos) from kaon decays expected in the framework of the SHiP experiment. The kaons are produced in the hadronic shower initiated in the beam-dump mode by 400 GeV protons from CERN SPS. For a sufficiently light HNL (when the decays are kinematically allowed) we find kaon decays to be a noticeably richer source of HNL as compared to $D$-meson decays adopted in previous studies of the HNL phenomenology at SHiP. In particular, SHiP is capable of fully exploring the central part of the kinematically allowed region of the HNL mass and mixing with electron and muon neutrinos down to the lower cosmological bound. The latter is associated with HNL decays in the early Universe to energetic products rescattering off and thus destroying light nuclei produced at the primordial nucleosynthesis. A consistency of the HNL model with smaller mixing would require either a hierarchy -- much larger mixing of all the HNL with tau neutrino -- or non-standard cosmology and new ingredients in the HNL sector, closing the room for the minimal non-seesaw type I model with sterile neutrinos lighter than kaons., Comment: 19 pages, 16 figures; replaced with journal version

Next generation neutrino experiments will push the limits in our understanding of astroparticle physics in the neutrino sector to energies orders of magnitude higher than the current state-of-the-art high-energy neutrino experiment, IceCube. These experiments will use neutrinos to tell us about the most extreme environments in the universe, while simultaneously leveraging these extreme environments as probes of neutrino properties at the highest energies accessible in the foreseeable future: $E\sim10^9$ GeV. At these energies neutrinos are readily absorbed in the Earth. Assuming an isotropic distribution, by looking at how the flux varies as a function of angle through the Earth, we show that it is possible to extract the $\nu_\tau$-$N$ cross section with precision at the $\sim20\%$ level ($1\sigma$ assuming Wilks' theorem) given $N_{\rm events}\sim100$ events., Comment: 7 pages, 5 figures, comments welcome; v2: minor changes, matches published version

During the first three flights of the Antarctic Impulsive Transient Antenna (ANITA) experiment, the collaboration detected several neutrino candidates. Two of these candidate events were consistent with an ultra-high-energy up-going air shower and compatible with a tau neutrino interpretation. A third neutrino candidate event was detected in a search for Askaryan radiation in the Antarctic ice, although it is also consistent with the background expectation. The inferred emergence angle of the first two events is in tension with IceCube and ANITA limits on isotropic cosmogenic neutrino fluxes. Here, we test the hypothesis that these events are astrophysical in origin, possibly caused by a point source in the reconstructed direction. Given that any ultra-high-energy tau neutrino flux traversing the Earth should be accompanied by a secondary flux in the TeV-PeV range, we search for these secondary counterparts in seven years of IceCube data using three complementary approaches. In the absence of any significant detection, we set upper limits on the neutrino flux from potential point sources. We compare these limits to ANITA's sensitivity in the same direction and show that an astrophysical explanation of these anomalous events under standard model assumptions is severely constrained regardless of source spectrum or time profile.

An event topology with two secondary vertices compatible with the decay of short-lived particles was found in the analysis of neutrino interactions in the Opera target. The observed topology is compatible with tau neutrino charged current (CC) interactions with charm production and neutrino neutral current (NC) interactions with $c\overline{c}$ pair production. However, other processes can mimic this topology. A dedicated analysis was implemented to identify the underlying process. A Monte Carlo simulation was developed and complementary procedures were introduced in the kinematic reconstruction. A multivariate analysis technique was used to achieve an optimal separation of signal from background. Most likely, this event is a $\nu_{\tau}$ CC interaction with charm production, the tau and charm particle decaying into 1 prong and 2 prongs, respectively. The significance of this observation is evaluated., Comment: 10 pages, 7 figures; Editors: Marco Roda, Chiara Sirignano and Gabriele Sirri

This paper posits that the upward-going ANITA events are derived from the cosmic ray of the baryonic-dark matter (BDM) Higgs boson. In the extended standard model (ESM) for baryonic matter and dark matter, the spontaneous symmetry breaking through the Higgs mechanism for the symmetrical massless baryonic matter left-handed neutrinos and massless dark matter right-handed neutrinos produced massless baryonic matter left-handed neutrinos, sterile massive dark matter neutrinos, and the BDM Higgs boson. The BDM Higgs boson is the composite of the high-mass tau neutrino and the high-mass dark matter neutrino. During the passage through the high-density part of the Earth, the BDM Higgs boson is transformed into the oscillating BDM Higgs boson between the composite of the high-mass tau neutrino and the high-mass dark matter neutrino and the composite of the high-mass tau neutrino and the low-mass dark matter neutrino. The oscillating BDM Higgs boson decays into the high-mass tau neutrino with the extra energy and the low-mass dark matter neutrino (27 eV) in the low-density water-ice layer of the Earth. The high-mass tau neutrino is converted into ultra-high-energy tau neutrino which decays into tau lepton through the charged-current interactions, and tau lepton emerges from the surface of ice. Based on the periodic table of elementary particles, the calculated value for the high-mass tau neutrino with the extra energy is 0.47 EeV in good agreement with the observed 0.56 and 0.6 EeV. The periodic table of elementary particles for baryonic matter, dark matter, and gravity is based on the seven principal mass dimensional orbitals for stable baryonic matter leptons (electron and left-handed neutrinos), gauge bosons, gravity, and dark matter and the seven auxiliary mass dimensional orbitals for unstable leptons (muon and tau) and quarks, and calculates accurately the masses of all elementary particles and the cosmic rays by using only five known constants.

Last two years high energy neutrino data are studied. The two recent tau neutrino double bang candidate are discussed within their detectability, noise and expected rate. The neutrino flavor distribution mainly favoring equal electron and muon presence, is reminded. The angular distribution of highest muon neutrino tracks is analyzed. Their horizontal strong anisotropy and their remarkable up-down asymmetry, with the absence of clustering, is noticed. The main persistent missing of astrophysical X,gamma sources (as GRB and AGN flaring source) and all the above signatures led us to suggest a dominance of prompt charmed (atmospheric) events able to pollute, to smear and to hide any minor astronomical presence., 15 pages, 4 figures, updated minimaized version, from earlier arxiv.org/abs/1808.10493v4; Volume 331, Frontier Research in Astrophysics, III (FRAPWS2018)

In the DsTau experiment at the CERN SPS, an independent direct way to study the tau neutrino production in high energy proton-nucleous interactions was proposed. Since the main source of tau neutrinos is a decay of Ds mesons, the project aims at measuring the differential cross-section of this reaction. The experimental method is based on the use of high-resolution emulsion detectors for the efficient registration of events with short-lived particle decays. The motivation of the project, details of the experimental technique, and the first results of the analysis of the data collected during test runs, which prove the feasibility of the study are presented., В рамках експерименту DsTau на приcкорювачi SPS в ЦЕРНi нами запропоновано незалежний та прямий спосiб дослiдження продукування тау-нейтрино в високоенергетичних зiткненнях протонiв з ядрами. Зважаючи не те, що основним джерелом нейтрино є розпад Ds-мезонiв, в проектi будуть вимiрюватись диференцiйнi перерiзи цього процесу. Методика експерименту базується на застосуваннi емульсiйних детекторiв для ефективної реєстрацiї подiй розпаду короткоживучих частинок. Нами представлено мотивацiю проекту, деталi експериментальної технiки, а також першi результати аналiзу даних з перших пробних сеансiв, що показали ефективнiсть нашого експерименту.

The IceCube Neutrino Observatory at the geographic South Pole has reached a number of milestones in the field of neutrino astrophysics. The achievements of IceCube include the discovery of a high-energy astrophysical neutrino flux, and the temporal and directional correlation of neutrinos with a flaring blazar. The IceCube Upgrade, which will be constructed in the 2022/23 Antarctic Summer season, is the next stage of the IceCube project. The IceCube Upgrade consists of seven new columns of photosensors, densely embedded near the bottom center of the existing cubic-kilometer-scale IceCube Neutrino Observatory. An improved atmospheric neutrino event selection efficiency and reconstruction at a few GeV can be achieved with the dense infill of the Upgrade's photosensor array. The Upgrade will provide world-leading sensitivity to neutrino oscillations and will enable IceCube to take unique measurements of tau neutrino appearance with a high precision. Furthermore, the new array will also improve the existing IceCube detector. The Upgrade strings will include new calibration devices designed to deepen the knowledge of the optical properties of glacial ice and the detector response. The improved calibration resulting from the Upgrade will be applied to the entire archive of IceCube data collected over the last 10 years, improving the angular and spatial resolution of the detected astrophysical neutrino events. Finally, the Upgrade represents the first stage in the development of IceCube-Gen2, the next-generation neutrino telescope at the South Pole., Presented at the 36th International Cosmic Ray Conference (ICRC 2019). See arXiv:1907.11699 for all IceCube contributions

Lepton universality in tau-neutrino ($\nu_\tau$) scattering has been poorly tested. More precise measurement of the $\nu_\tau$ cross section would enable a search for new physics effects in $\nu_\tau$-nucleon CC interactions. Such measurement also has practical importance for next-generation neutrino oscillation experiments and astrophysical $\nu_\tau$ observations. The DsTau project has been proposed at CERN SPS to study tau-neutrino production with the aim of providing important data for future $\nu_\tau$ measurements. For $\nu_\tau$ cross section measurements, the practical method of producing an artificial $\nu_\tau$ beam employs the sequential decay of $D_s$ mesons produced in high-energy proton interactions. However, there has been no experimental measurement of the $D_s$ differential production cross section in fixed-target experiments using proton beams, which leads to a large systematic uncertainty on the $\nu_\tau$ flux estimation. The DsTau project aims to reduce this uncertainty in the current cross section measurement from about 50% to 10% by measuring the $D_s$ differential production cross section. For this purpose, emulsion detectors with a 50-nm spatial resolution will allow the detection of $D_s \rightarrow \tau \rightarrow X$ double kinks in a few mm range. Results from the beam tests conducted in 2016-2017 are presented together with a prospect for the pilot run in 2018 and the physics run in 2021.

In this paper the production cross section $pp\rightarrow (\gamma, Z) \to \nu_\tau \bar \nu_\tau \gamma+X$ in $pp$ collisions at $\sqrt{s}=8, 13, 14, 33TeV$ is presented. Furthermore, we estimate bounds at the $95\%C. L.$ on the dipole moments of the tau-neutrino using integrated luminosity of ${\cal L}=20, 50, 100, 200, 500, 1000, 3000 fb^{-1}$ collected with the ATLAS detector at the LHC and we consider systematic uncertainties of $\delta_{sys}=0, 5, 10\%$. It is shown that the process under consideration is a good prospect for probing the dipole moments of the tau-neutrino at the LHC., Comment: 20 pages, 12 figures

Cosmic neutrinos above a PeV are produced either within astrophysical sources or when ultra-high energy cosmic rays interact in transit through the cosmic background radiation. Detection of these neutrinos will be essential for understanding cosmic ray acceleration, composition and source evolution. By using the Earth as a tau neutrino converter for upward-going extensive air showers from tau decays, balloon-borne and space-based instruments can take advantage of a large volume and mass of the terrestrial neutrino target. The theoretical inputs and uncertainties in determining the tau lepton exit probabilities and their translation to detection acceptance will be discussed in the context of a new calculation we have performed. We quantify the experimental detection capability based on our calculation, including using the Probe of Extreme Multi-Messenger Astrophysics (POEMMA) concept study response parameters for optical air Cherenkov detection. These case studies are used to illustrate the features and uncertainties in upward tau air shower detection., Comment: 8 pages, 3 figures, Proceedings of the 36th International Cosmic Ray Conference (ICRC 2019), held July 24th - August 1st, 2019 in Madison, WI, USA