Search results for "NEUTRINO"
showing 10 items of 1752 documents
Search for Multimessenger Sources of Gravitational Waves and High-energy Neutrinos with Advanced LIGO during Its First Observing Run, ANTARES, and Ic…
2019
[EN] Astrophysical sources of gravitational waves, such as binary neutron star and black hole mergers or core-collapse supernovae, can drive relativistic outflows, giving rise to non-thermal high-energy emission. High-energy neutrinos are signatures of such outflows. The detection of gravitational waves and high-energy neutrinos from common sources could help establish the connection between the dynamics of the progenitor and the properties of the out¿ow. We searched for associated emission of gravitational waves and high-energy neutrinos from astrophysical transients with minimal assumptions using data from Advanced LIGO from its first observing run O1, and data from the ANTARES and IceCub…
Genuine and Matter-induced Components of the CPV Asymmetry for Neutrino Oscillations
2019
These results represent the solution for the historical problem of the contamination by matter effects on the CPV Asymmetry for neutrino oscillations. Vacuum is CPT-symmetric and matter is T-symmetric, the goal is accomplished by using this guiding principle. Independent of the theoretical framework for the dynamics of the active neutrino flavors, we prove the Disentanglement Theorem A(CP)=A(CP, T)+A(CP, CPT) for the experimental CPV Asymmetry, with A(CP, T) genuine T-odd and A(CP, CPT) fake CPT-odd. For the effective Hamiltonian written as the sum of free mass propagation plus the matter potential for electron-neutrinos, the two components have definite parities under the baseline L, the m…
Testing the mechanism of R-parity breaking with slepton LSP decays
2003
In supersymmetric models R-parity can be violated through either bilinear or trilinear terms in the superpotential, or both. If charged scalar leptons are the lightest supersymmetric particles, their decay properties can be used to obtain information about the relative importance of these couplings. We show that in some specific scenarios it is even possible to decide whether bilinear or trilinear terms give the dominant contribution to the neutrino mass matrix.
New leptoquark mechanism of neutrinoless double beta decay
1996
A new mechanism for neutrinoless double beta ($\znbb$) decay based on leptoquark exchange is discussed. Due to the specific helicity structure of the effective four-fermion interaction this contribution is strongly enhanced compared to the well-known mass mechanism of $\znbb$ decay. As a result the corresponding leptoquark parameters are severely constrained from non-observation of $\znbb$-decay. These constraints are more stringent than those derived from other experiments.
Neutrino energy reconstruction and the shape of the charged current quasielastic-like total cross section
2012
We show that because of the multinucleon mechanism effects, the algorithm used to reconstruct the neutrino energy is not adequate when dealing with quasielastic-like events, and a distortion of the total flux-unfolded cross-section shape is produced. This amounts to a redistribution of strength from high to low energies, which gives rise to a sizable excess (deficit) of low (high) energy neutrinos. This distortion of the shape leads to a good description of the MiniBooNE unfolded charged current quasielastic-like cross sections published by A. A. Aguilar-Arevalo et al. [(MiniBooNE Collaboration), Phys. Rev. D 81, 092005 (2010)]. However, these changes in the shape are artifacts of the unfol…
Dark matter stability and Dirac neutrinos using only Standard Model symmetries
2020
We provide a generic framework to obtain stable dark matter along with naturally small Dirac neutrino masses generated at the loop level. This is achieved through the spontaneous breaking of the global $U(1)_{B-L}$ symmetry already present in Standard Model. The $U(1)_{B-L}$ symmetry is broken down to a residual even $\mathcal{Z}_n$; $n \geq 4$ subgroup. The residual $\mathcal{Z}_n$ symmetry simultaneously guarantees dark matter stability and protects the Dirac nature of neutrinos. The $U(1)_{B-L}$ symmetry in our setup is anomaly free and can also be gauged in a straightforward way. Finally, we present an explicit example using our framework to show the idea in action.
Radiative neutrino masses: A window to new physics
2021
Currently, the Standard Model of particle physics (SM) is the best theory we have to describe particles and their interactions. However, there is evidence of physics beyond it, which motivates us to seek for a more complete theory. Neutrino oscillations constitute the first experimental confirmation of new physics, as they require a new piece that is absent in the SM, non-zero neutrino masses. Neutrino masses brought new theoretical challenges, for instance questions as how these masses are generated or why are they so small compared to other masses, are still under investigation. In this thesis, we aim to study radiative neutrino mass models, a class of models where small neutrino masses a…
Positive Muons as Local Probes in Paramagnetic Rare Earth Systems
1982
In recent years a new research method has been developed in solid state physics which is based on the asymmetry of muon decay1. A positive muon at rest decays after a mean lifetime of 2.2 μsec into a positron and two neutrinos, the positron being emitted preferentially in the direction of the muon spin. Hence if spin polarized muons are implanted in a solid, the time evolution of the muon spin polarization can be determined by a measurement of the angular distribution of the positrons. In an external magnetic field transverse to the initial spin direction of the muon one can study the muon spin precession frequency, which is determined by the actual field at the muon, and τ2-relaxation effe…
Constraints on neutrino speed, weak equivalence principle violation, Lorentz invariance violation, and dual lensing from the first high-energy astrop…
2019
We derive stringent constraints on neutrino speed, weak equivalence principle violation, Lorentz invariance violation, and dual lensing from the first high-energy astrophysical neutrino source: TXS $0506+056$. Observation of neutrino (IceCube-170922A) and photons in a similar time frame and from the same direction is used to derive these limits. We describe ways in which these constraints can be further improved by orders of magnitude.
Solar neutrino physics with Borexino
2018
We present the most recent solar neutrino results from the Borexino experiment at the Gran Sasso underground laboratory. In particular, refined measurements of all neutrinos produced in the {\it pp} fusion chain have been made. It is the first time that the same detector measures the entire range of solar neutrinos at once. These new data weakly favor a high-metallicity Sun. Prospects for measuring CNO solar neutrinos are also discussed.