Narrow Results

We discuss the possible violation of local Lorentz invariance (LLI) arising from a faster-than-light neutrino speed. A toy calculation of the LLI violation parameter $\delta$, based on the (disclaimed) OPERA data, suggests that the values of $\delta$ are determined by the interaction involved, and not by the energy range. This hypothesis is further corroborated by the analysis of the more recent results of the BOREXINO, LVD and ICARUS experiments.

We examine dark matter annihilation in galaxy halos. By considering annihilation into all Standard Model particles we show that the least detectable final states, namely neutrinos, define a strong general upper bound on the total cross section. This limit is much stronger than the unitarity bound in the most interesting mass range and implies annihilation cannot significantly modify dark matter halo density profiles. We also calculate conservative upper limits on the self-annihilation cross section to monoenergetic gamma rays over a wide range of dark matter masses, using gamma-ray data from the Milky Way, Andromeda (M31), and the cosmic background. We compare gamma-ray-based and neutrino-based upper limits on the total cross section.

We place a nre upper limit on the sum of neutrino masses by using measurements of luminosity-dependent galaxy bias at several different redshifts, SDSS at z = 0.05, DEEP2 at z = 1 and LBGs at z = 3.8, combined with WMAP five-year cosmic microwave background anisotropy data and SDSS Red Luminous Galaxy survey three-dimensional clustering power spectrum. We obtain the upper limit of ∑ m_ν < 0.28eV at the 95% confidence level for a ΛCDM + m_ν model, with a σ₈ equal to σ₈ = 0.759 ± 0.025 (1σ). When we allow the dark energy equation of state parameter w to vary we find w = -1.30 ± 0.19 for a general wCDM + m_ν model with the 95% confidence level upper limit on the neutrino masses at ∑ m_ν < 0.59eV. Finally, we have investigated the ability of the future Euclid mission to constrain differences in the mass of individual neutrino species.

By taking magnetic field and detailed microphysics into account, we calculate the structure of neutrino-dominated disk in the frame of the well-known Paczyski-Witta potential, and compare the results with those without magnetic field. The results show that the temperature of the disk is lower than that without magnetic field, whereas the density is nearly the same as that without magnetic field. There also exists difference in the composition of disk matter between these two cases in the inner region of the disk.

We present the neutrino and UHECR spectra obtained from a detailed fitting of the spectral energy distribution (SED) of Mrk 421 (March 2001) using two variations of the leptohadronic model. In particular, while the low-energy component (optical to X-rays) of the SED is fitted by synchrotron emission of primary electrons in both models, the high-energy one (GeV-TeV gamma-rays) is synchrotron emission attributed either to ultra-high energy protons (LHs model) or to secondary electrons produced by the decay of charged pions (LHπ model). In the LHπ case we find that the produced neutrino spectra are sharply peaked at E_ν ~ 30 PeV with a peak flux slightly below the IC-40 sensitivity limit for Mrk 421. In the LHs model, on the other hand, the neutrino spectra fall well outside the PeV energy range, but the calculated E ~ 30 EeV — UHECR flux at earth is close to that observed by HiresI, Telescope Array and Pierre Augere experiments.

We present preliminary results of a model with two zones in order to study the production of high energy neutrinos at the prompt phase of gamma-ray bursts (GRB). We consider an acceleration zone, where protons and electrons are injected and accelerated, being subject to synchrotron, proton-proton, and proton-gamma cooling. We also assume that they can escape from this zone at a certain rate. The produced pions and the decaying muons are also subject to energy loss and gain processes within the acceleration zone, and the escaping ones are re-injected in a second zone where acceleration no longer operates. We compute the neutrino output expected from both of these zones using typical GRB parameters, and integrate in the redshift to obtain a diffuse neutrino flux which can be different from the expected within one-zone models.

The lepton-charge (L_e, L_μ, L_τ) nonconserving interaction leads to the mixing of the electron, muon and tau neutrinos, which manifests itself in spatial oscillations of a neutrino beam, and also to the mixing of the electron, negative muon and tau lepton, which, in particular, may be the cause of the "forbidden" radiative decay of the negative muon into the electron and γ quantum. Under the assumption that the nondiagonal elements of the mass matrices for neutrinos and ordinary leptons, connected with the lepton charge nonconservation, are the same, and by performing the joint analysis of the experimental data on neutrino oscillations and experimental restriction for the probability of the decay μ^- → e^- + γ per unit time, the following estimate for the lower bound of neutrino mass has been obtained: .

We revive the historically first neutrino dark matter model, but with an additional assumption that neutrinos might exist in tachyonic almost sterile states. To this end we propose a group-theoretical algorithm for the description of tachyons. The key point is that we employ a distinct tachyon Lorentz group with another (superluminal) parametrization which does not require traditional introduction of imaginary masses and negative energies, and therefore does not lead to violation of causality and unitarity. Our dark matter model represents effectively scalar tachyonic neutrino-antineutrino conglomerate. Distributed all over the universe, such fluid behaves as stable isothermal/stiff medium which produces somewhat denser regions (‘smoothed halos’) around galaxies and clusters. It is shown to be consistent with observational effects (galactic rotation curves).

The SN1987A in the Giant Magellanic Cloud was an amazing and extraordinary event because it was detected in real time for different neutrinos experiments ($\nu$s) around the world. Approximate $\sim 25$ events were observed in three different experiments: Kamiokande II (KII) $\sim 12$, Irvine-Michigan-Brookhaven (IMB) $\sim 8$ e Baksan $\sim 5$, plus a contrived burst at Mont Blanc (Liquid Scintillator Detector - LSD) later dismissed because of energetic requirements (Aglietta et al. 1988). The neutrinos have an important play role into the neutron star newborn: at the moment when the supernova explodes the compact object remnant is freezing by neutrinos ($\sim 99\%$ energy is lost in the few seconds of the explosion). The work is motivated by neutrinos’ event in relation arrival times where there is a temporal gap between set of events ($\sim 6\text{s}$). The first part of dataset came from the ordinary mechanism of freezing and the second part suggests different mechanism of neutrinos production. We tested two models of cooling for neutrinos from SN1987A: 1st an exponential cooling is an ordinary model of cooling and 2nd a two-step temperature model that it considers two bursts separated with temporal gap. Our analysis was done with Bayesian tools (Bayesian Information Criterion - BIC) The result showed strong evidence in favor of a two-step model against one single exponential cooling ($ln{\text{B}}_{ij}>5.0$), and suggests the existence of two neutrino bursts at the moment the neutron star was born.

The NOvA experiment is a long-baseline accelerator-based neutrino oscillation experiment. It uses the upgraded NuMI beam from Fermilab to measure electron-neutrino appearance and muon-neutrino disappearance between the Near Detector, located at Fermilab, and the Far Detector, located at Ash River, Minnesota. The NuMI beam has recently reached and surpassed the 700 kW power benchmark. NOvA’s primary physics goals include precision measurements of oscillation parameters, such as ${𝜃}_{23}$ and the atmospheric mass-squared splitting, along with probes of the mass hierarchy and of the CP violating phase. This talk will present the latest NOvA results, based on a neutrino beam exposure equivalent to $6.05\times 10^{20}$ protons-on-target.

The goal of the NEXT collaboration is the sensitive search of the neutrino-less double beta decay ($\beta {\beta }^{0\nu }$) of ${}^{136}$Xe at the LSC. After a successful R&D phase, a first large-scale prototype of a high-pressure gas-Xenon electroluminescent TPC (NEW) is being operated at LSC since 2016. NEW is a 10-kg radiopure detector meant to understand the relevant backgrounds for the $\beta {\beta }^{0\nu }$search and to perform a measurement of the two neutrino mode of the double beta decay ($\beta {\beta }^{2\nu }$). The first phase of the NEW physics program comprises the commissioning of the detector and the data taking with calibration sources. This phase has allowed to understand the detector capabilities in terms of energy resolution and event topology reconstruction. The operation of NEW is setting the grounds for the construction of the NEXT-100 detector: a TPC holding 100 kg of ${}^{136}$Xe and reaching a sensitivity to the $\beta {\beta }^{0\nu }$half-life of $6\times 10^{25}$ y after 3 years of data taking. The latest results of the NEW detector as well as the status of the NEXT-100 project are presented.

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 $2\times 10^{20}$ 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.