Search results for "Oscillations"
showing 10 items of 238 documents
Effect of coronal loop structure on wave heating through phase mixing
2020
Context. The mechanism(s) behind coronal heating still elude(s) direct observation and modelling of viable theoretical processes and the subsequent effect on coronal structures is one of the key tools available to assess possible heating mechanisms. Wave heating via the phase mixing of magnetohydrodynamic (MHD) transverse waves has been proposed as a possible way to convert magnetic energy into thermal energy, but MHD models increasingly suggest this is not an efficient enough mechanism. Aims. We modelled heating by phase mixing transverse MHD waves in various configurations in order to investigate whether certain circumstances can enhance the heating sufficiently to sustain the million deg…
Additional results from the first dedicated search for neutron–mirror neutron oscillations
2008
International audience; The existence of a mirror world holding a copy of our ordinary particle spectrum could lead to oscillations between the neutron (n) and its mirror partner (n′). Such oscillations could manifest themselves in storage experiments with ultracold neutrons whose storage lifetime would depend on the applied magnetic field. Here, extended details and measurements from the first dedicated experimental search for nn′ oscillations published in [G. Ban, K. Bodek, M. Daum, R. Henneck, S. Heule, M. Kasprzak, N. Khomutov, K. Kirch, S. Kistryn, A. Knecht, P. Knowles, M. Kuźniak, T. Lefort, A. Mtchedlishvili, O. Naviliat-Cuncic, C. Plonka, G. Quéméner, M. Rebetez, D. Rebreyend, S. R…
Neutron Fermi liquids under the presence of a strong magnetic field with effective nuclear forces
2009
Landau's Fermi liquid parameters are calculated for non-superfluid pure neutron matter in the presence of a strong magnetic field at zero temperature. The particle-hole interactions in the system, where a net magnetization may be present, are characterized by these parameters in the framework of a multipolar formalism. We use either zero- or finite-range effective nuclear forces to describe the nuclear interaction. Using the obtained Fermi liquid parameters, the contribution of a strong magnetic field on some bulk magnitudes such as isothermal compressibility and spin susceptibility is also investigated.
A $B_4C$-silicon target for the detection of neutrino interactions
1998
This note describes the construction of a target for neutrino interactions composed of passive boron carbide plates interleaved with silicon microstrip detectors. The target contains four layers of passive material with a total mass of 45 kg and 600 single--sided silicon microstrip detectors with a total surface of 1.14 m$^2$ distributed over five layers. It is installed in the NOMAD spectrometer at the CERN SPS neutrino beam. During the 1997 run about 8000 \nm\ charged current interactions were estimated to have occurred in the target. For these events it will be possible to perform a precise measurement of both vertex and kinematical variables. This will provide invaluable experience towa…
Cosmological radiation density with non-standard neutrino-electron interactions
2021
Neutrino non-standard interactions (NSI) with electrons are known to alter the picture of neutrino decoupling from the cosmic plasma. NSI modify both flavour oscillations through matter effects, and the annihilation and scattering between neutrinos and electrons and positrons in the thermal plasma. In view of the forthcoming cosmological observations, we perform a precision study of the impact of non-universal and flavour-changing NSI on the effective number of neutrinos, $N_{eff}$. We present the variation of $N_{eff}$ arising from the different NSI parameters and discuss the existing degeneracies among them, from cosmology alone and in relation to the current bounds from terrestrial exper…
Status and implications of neutrino masses: a brief panorama
2015
15 pages.- 10 figures
Search for νμ→νe oscillations in the NOMAD experiment
2003
We present the results of a search for vμ → v e oscillations in the NOMAD experiment at CERN. The experiment looked for the appearance of ve in a predominantly vμ wide-band neutrino beam at the CERN SPS. No evidence for oscillations was found. The 90% confidence limits obtained are Δm2 < 0.4 eV 2 for maximal mixing and sin2(2θ) < 1.4 × 10-3 for large Δm2. This result excludes the LSND allowed region of oscillation parameters with Δm2 ≳ 10 eV2. © 2003 Elsevier B.V. All rights reserved.
Golden measurements at a neutrino factory
2000
The precision and discovery potential of a neutrino factory based on muon storage rings is studied. For three-family neutrino oscillations, we analyse how to measure or severely constraint the angle $\theta_{13}$, CP violation, MSW effects and the sign of the atmospheric mass difference $\Delta m^2_{23}$. We present a simple analytical formula for the oscillation probabilities in matter, with all neutrino mass differences non-vanishing, which clarifies the subtleties involved in disentangling the unknown parameters. The appearance of ``wrong-sign muons'' at three reference baselines is considered: 732 km, 3500 km, and 7332 km. We exploit the dependence of the signal on the neutrino energy, …
Neutrino mixing with revamped A(4) flavor symmetry
2013
We suggest a minimal extension of the simplest A(4) flavor model that can induce a nonzero theta(13) value, as required by recent neutrino oscillation data from reactors and accelerators. The predicted correlation between the atmospheric mixing angle theta(23) and the magnitude of theta(13) leads to an allowed region substantially smaller than indicated by neutrino-oscillation global fits. Moreover, the scheme correlates CP violation in neutrino oscillations with the octant of the atmospheric mixing parameter theta(23) in such a way that, for example, maximal mixing necessarily violates CP. We briefly comment on other phenomenological features of the model.
New constraints on coupled dark energy from the Planck satellite experiment
2013
We present new constraints on coupled dark energy from the recent measurements of the cosmic microwave background anisotropies from the Planck satellite mission. We found that a coupled dark energy model is fully compatible with the Planck measurements, deriving a weak bound on the dark matter-dark energy coupling parameter xi = -0.49(-0.31)(+0.19) at 68% C.L. Moreover if Planck data are fitted to a coupled dark energy scenario, the constraint on the Hubble constant is relaxed to H-0 = 72.1(-2.3)(+3.2) km/s/Mpc, solving the tension with the Hubble Space Telescope (HST) value. We show that a combined PLANCK + HST analysis provides significant evidence for coupled dark energy finding a nonzer…