Types Of Neutrinos Research Articles

Coalescing neutron stars as gamma ray bursters?

We investigate the dynamics and evolution of coalescing neutron stars. The three-dimensional Newtonian equations of hydrodynamics are integrated by the `Piecewise Parabolic Method' However, we do include the effects of the emission of gravitational waves on the hydrodynamics. The properties of neutron star matter are described by the equation of state of Lattimer & Swesty. In addition to the fundamental hydrodynamic quantities, density, momentum, and energy, we follow the time evolution of the electron density in the stellar gas. Energy losses and changes of the electron abundance due to the emission of neutrinos are taken into account by an elaborate ``neutrino leakage scheme'', which employs a careful calculation of the lepton number and energy source terms of all neutrino types. The grid is Cartesian and equidistant with a resolution of 64**3 or 128**3, which allows us to calculate the self-gravity via fast Fourier transforms.

Some remarks on the problem of neutrino oscillation in vacuum and matter

The paper deals with the analysis of possible neutrino oscillation types in vacuum and matter. The conclusion is that: 1) If masses of different types of neutrions are equal, then a real oscillation of different types of neutrinos is possible by analogy with K0,\(\bar K^0 \) oscillation. 2) If masses of different types of neutrinos are different, then only a virtual neutrino oscillation is possible, and a real oscillation of neutrinos requires their participation in the interactions for transition to the appropriate to the ϱ0-meson in the vector dominance model. The enhanced oscillation probability is estimated for neutrinos of different masses in their passing through matter of different thickness, including the Sun. If it is assumed that the deficit of Sun neutrinos arises from neutrino oscillations, then using the GALLEX and SSM data we obtain that sin22г≅0.015.

On the spectrum of neutrino mass in general relativity

The problem of neutrino mass is investigated in the context of the author’s research program on the possible origin of microphysics from general relativity. It is found that the role of the «neutrino» in this theory is that of a spin-one-half coupling field that participates in the weak interactions between baryons. It is shown that in a curved space-time, the neutrino field associates with an indefinitely extended mass spectrum, accompanying the spectrum of the lepton particles, e, μ, τ, …. The explicit form of the mass spectrum, in the linear limit of the theory, where there is a Hilbert-space representation, is demonstrated. This result is in contrast with recent conclusions from the results of high-energy physics experimentation, interpreted in the context of the «standard model» in quantum chromodynamics, that there is a limit of only three neutrinos, and the accompanying three lepton particles, e, μ, τ. The author’s theory then challenges QCD in its prediction of more than three types of neutrinos and their accompanying massive leptons.

Majoron decay in matter

It is well known that matter can significantly alter the picture of neutrino oscillation [1] or neutrino decay [2]. Here we show that the presence of dense matter induces also the decay of massless majoron, a Goldstone boson associated with the spontaneous lepton number violation, into a couple of neutrinos with the same (or in some cases also opposite) helicities. We calculate the rates of such matter induced majoron decays in various cases, depending on the neutrino type and the chemical content of the medium, and analyse their properties.

Limits on neutrino mixing with new heavy particles

We study the effects induced by new neutral fermions below their mass threshold, due to their possible mixing with the standard neutrinos. We use as experimental constraints the recent results on lepton universality, together with the measurement of the μ decay rate and the updated LEP data. In particular, the inclusion in our data set of the most recent determinations of the τ branching fractions, mass and lifetime implies that a previous indication of a non-vanishing mixing for ν τ is no longer present. We obtain new stringent limits on the mixing parameters between ν e , ν μ, ν τ and heavy neutral states of different weak isospin. If no assumption on the type of neutrinos involved in the mixing is made, we find s ν e 2<0.0071 , s ν μ 2<0.0014 and s ν τ 2<0.033.

Geminga: A cooling superfluid neutron star

We show that Geminga's surface temperature can be understood by both types of neutrino cooling scenarios, i.e, slow neutrino cooling by the modified Urca process or fast neutrino cooling by the direct Urca process or by some exotic matter, and thus does not allow us to discriminate between these two competing schemes. However, for both types of scenarios, agreement with the observed temperature can only be obtained if BARYON PAIRING IS PRESENT IN MOST, IF NOT ALL, OF THE CORE OF THE STAR. We also comment on the recent temperature estimates for PSR 0656+14 and PSR 1055-52, which pertain to the same photon cooling era. We argue though that observational evidence for the slow neutrino cooling model (the ``standard'' model) is in fact very dim and that the interpretation of the surface temperature of all neutron stars could be done with a reasonable theoretical a priori within the fast neutrino cooling scenarios only. In this case, Geminga, PSR 0656+14, and PSR 1055-52 all show evidence of baryon pairing down to their very centers. xxx----To be published in Ap.J. (June 10 isue).---xxx

NOTE ON THE MEASUREMENT OF y-DEPENDENCE IN NEUTRINO-ELECTRON SCATTERING: A SENSITIVE TEST OF THE STANDARD MODEL

It is pointed out that the y-dependence of the differential cross-section for various types of neutrinos on the electron promises to be a sensitive testing ground of the electroweak Standard Model at KAON in Vancouver. Estimates of the flux requirements are given and the feasibility of such experiments is discussed.

Future Solar Neutrino Experiments.

The status of several neutrino experiments now being constructed and others under development is reviewed. These experiments have the potential to provide higher statistics, sensitivity to all neutrino types and different energy thresholds than presently available. The results from this next generation of experiments could provide an explanation for the low solar neutrino fluxes observed to date.

Limits on neutrino oscillations from nu -bare appearance.

A 20-ton neutrino detector located near the Los Alamos Meson Physics Facility beam stop is used to search for [bar [nu]][sub [ital e]] generated via neutrino oscillations from any of the three neutrino types, [nu][sub [mu]], [bar [nu]][sub [mu]], and [nu][sub [ital e]], which radiate from the beam stop. The analysis of three years of data provides limits on the oscillation modes [bar [nu]][sub [mu]][r arrow][bar [nu]][sub [ital e]], [nu][sub [ital e]][r arrow][bar [nu]][sub [ital e]], and [nu][sub [mu]][r arrow][bar [nu]][sub [ital e]], and the lepton-number-violating decay process [mu][sup +][r arrow][ital e][sup +]+[bar [nu]][sub [ital e]]+[nu][sub [mu]]. The 90%-confidence-level limits for [bar [nu]][sub [mu]][r arrow][bar [nu]][sub [ital e]] oscillations are [delta][ital m][sup 2][le]0.14 eV[sup 2] for maximal mixing, and sin[sup 2]2[theta][le]0.024 for large [delta][ital m][sup 2].

Search for isosinglet neutral heavy leptons in Z 0 decays

We search for neutral heavy leptons that are isosinglets under the standard SU (2) L gauge group. Such neutral heavy leptons are expected in many extensions of the standard model. Three types of heavy leptons N e, N μ, N τ associated with the three neutrino types v e , v μ , v τ have been directly searched for and no evidence for a signal has been found. We set the limit Br(N Su0 → v ℓN ℓ) < 3 x 10 −5 at the 95% CL for mass range from 3 GeV up to M z .

Four-family lepton mixing.

We introduce a fourth family of heavy leptons and discuss the lepton mixing matrix. In the minimal case of three massless neutrino types, the lepton mixing matrix is parametrized by three real angles and no phases, and leads to electron, $\ensuremath{\mu}$, and $\ensuremath{\tau}$ number nonconservation which provides experimental limits on the three angles.

The Sudbury Neutrino Observatory

The Sudbury Neutrino Observatory (SNO) detector is a 1000 ton heavy water (D 2O) Cherenkov detector designed to study neutrinos from the sun and other astrophysical sources. The use of heavy water allows both electron neutrinos and all other types of neutrinos to be observed by three complementary reactions. The detector will be sensitive to the electron neutrino flux and energy spectrum shape and to the total neutrino flux irrespective of neutrino type. These measurements will provide information on both vacuum neutrino oscillations and matter-enhanced oscillations, the MSW effect. In the event of a supernova it will be very sensitive to muon and tau neutrinos as well as the electron neutrinos emitted in the initial burst, enabling sensitive mass measurements as well as providing details of the physics of stellar collapse.

Gauge model for testing compositeness in electron-positron collisions

We present a composite scenario based on the SU{sub {ital L}}(2){direct product}U(1){sub {ital Y}}{direct product}SU{sub {ital L}}{sup *}(2) group. New interactions are predicted at the usual electroweak scale. New heavy fermions can be produced in a renormalizable model. A new type of light excited neutrinos can occur and are shown to be naturally consistent with the recent results from the CERN {ital e}{sup +}{ital e{minus}} collider LEP on the {ital Z} width.

Consistent neutrino masses from cosmology and solar physics

THE solar neutrino problem and cosmological dark matter can both be accounted for by non-zero neutrino masses1–5 that are broadly compatible with the so-called 'see-saw' relation, which comes from a simple theoretical model6 for the neutrino masses and according to which the mass of each neutrino type is proportional to the square of the mass of the associated quark. Recently both the solar and the cosmological estimates of neutrino masses have been considerably improved. New solar neutrino data7 lead to a more precise constraint8,9 on the masses of the electron and either the muon or tau neutrinos if the dearth of detected solar neutrinos is ascribed to resonantly enhanced mixing of neutrino types within the Sun (the MSW effect10,11). In addition, if galactic H I ionization is a consequence of decaying tau neutrinos that constitute dark matter, a more precise estimate of the tau neutrino mass follows12. Here I point out that these more accurate estimates still conform to the see-saw relation, a result which, unless it is a chance agreement, ties together three unproven hypotheses: the see-saw mechanism, the MSW effect and the decaying neutrino hypothesis.

Neutrinos from type II supernovae - The first 100 milliseconds

The collapse of a 1.17 solar mass iron core is numerically followed through infall to 100 ms past core bounce, and the emergent neutrino spectra during each phase are highlighted. It is found that, even with fairly optimistic conditions for producing a strong, sustained core-bounce shock wave, the prompt shock stalls within 9 ms of core bounce at a radius of less than 250 km. It appears that a radical change in the character of the progenitor core or in our understanding of the relevant physics of stellar collapse is needed before the direct mechanism for type II supernovae can become viable. Expanding the number of neutrino types from one to six magnifies the debilitating effect of neutrino loss on shock propagation. At shock breakout, prompt bursts of all neutrino types are observed. The luminosities of the nonelectron types show a sudden turn-on in luminosity while that of the electron neutrinos steadily increases throughout infall as a result of accelerating electron capture.

Topological quasi-charges in the Einstein theory of teleparallelism and particle combinatorics

A Riemann space with absolute parallelism is considered. Geometry is given by the field of n-frames h μ a . It is shown that for a localized field configuration h one can define a topological charge — an element of the homotopy group Gm= πm(SOm), m=n−1. The most interesting case of m=6, G6=0, is considered in detail. Even though in this case there is no topological charge, for configurations symmetrical in κ dimensions, one can define a quasi-charge — an element of the group G6−κ. The groups G3, G4, G5 may correspond to elementary particles (quasiparticles) of the photon, electron, and neutrino types, accordingly. The combinatorics emerging from this scheme is compared with the observation.

Primordial nucleosynthesis corners the Z′

We investigate the implications on the Z′ gauge boson parameters that come from enforcing the primordial nucleosynthesis constraints on the effective number of neutrino-like degrees of freedom in the presence of a Z′ that couples to three types of light right-handed neutrinos. We obtain stringent bounds on the Z-Z′ mixing angle, −0.004 ≲ φ ⩽ 0, and on the mass of the heavy eigenstate, M 2 ≳ 1 TeV. These bounds are stronger than the current experimental limits derived from precise measurements of the electroweak gauge boson masses. In this case we also find that the effect of Z-Z′ mixing on the Z width is completely negligible, and hence that it could not account for any small (positive or negative) shift on the Z width with respect to the standard model value.

Constraints on SN 1987A neutrino types from the Homestake Mine detectors

view Abstract Citations (2) References (7) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Constraints on SN 1987A Neutrino Types from the Homestake Mine Detectors Fireman, E. L. Abstract Data obtained with the Homestake Mine chlorine solar neutrino detector constrain the vmu_'s and vtau_'s as well as the v_e_'s in the supernova SN 1987A neutrino burst. The proton production in this detector by the vmu_ and vtau_, neutrino types is calculated and the ^37^Ar production by the protons is obtained. The sensitivities of the Homestake Mine chlorine detector for the v_e_, vmu_, and vtau_, neutrinos from SN 1987A are higher than those of the Kamiokande II detector only for v_e_'s of energy less than 15 Mev and for large vmu_ and vtau_ masses. Publication: The Astrophysical Journal Pub Date: January 1990 DOI: 10.1086/168309 Bibcode: 1990ApJ...349..241F Keywords: Neutrinos; Nuclear Astrophysics; Supernova 1987a; Argon Isotopes; Protons; Radiation Detectors; Space Radiation; NEUTRINOS; STARS: INDIVIDUAL ALPHANUMERIC: SN 1987A; STARS: SUPERNOVAE full text sources ADS | data products NED (2) SIMBAD (1)

Determination of the leptonic branching ratios of the Z

The ratios of the numbers of Z bosons decaying to e +e −, μ +μ − and τ +τ − pairs to the number decaying to hadrons have been measured. The branching ratios and partial widths for each channel were determined and found to be equal, consistent with lepton universality. The mean leptonic branching ratio was found to be 0.0321 ± 0.0013 and the leptonic partial width to be 85.4 ± 5.3 MeV. The partial widths for hadronic decays and for invisible decays were deduced to be 1833 ± 116 MeV and 569 ± 92 MeV, respectively. The number of light neutrino types, assuming only the standard model value for the ratio Θ e Θ v , was found to be 3.35 ± 0.41.

LEP's prompt abundance

Never have so many physicists gained so much so quickly from one machine. On 14 July a particle beam circulated around CERN's LEP ring for the first time. On 13 August, circulating beams of electrons and positrons were brought into collision for the first time, and the first Z0 particles were produced and detected within a few minutes. The first physics run of the machine started on 18 September, and was completed on 9 October. On 13 October the first physics results of the four LEP experimental collaborations were presented to a packed audience at CERN (Physics World November p6). The new measurements that were reported of the mass and ‘decay width’ of the Z0 and of the number of neutrino types are important not only in themselves but also for their implications for unseen entities such as the top quark, the Higgs boson and particles whose existence is predicted by theories of supersymmetry.