Neutrinos and Nucleosynthesis in Supernova

The type II supernova is considered as a candidate site for the production of heavy elements. The nucleosynthesis occurs in an intense neutrino flux, we calculate the electron fraction in this environment.Comment: RevTex4 style, 3 pages including 1 figure. Presented at Mexican School of Astrophysics 2002, Guanajuato, Mexico, 31 Jul - 7 Aug 2002. Final version to appear in the Proceedings of IX Mexican Workshop on Particles and Fields Physics Beyond the Standard Model, Colima Col. Mexico, November 17-22, 200

A comprehensive study of neutrino spin-flavour conversion in supernovae and the neutrino mass hierarchy

Resonant spin-flavour (RSF) conversions of supernova neutrinos, which is induced by the interaction between the nonzero neutrino magnetic moment and supernova magnetic fields, are studied for both normal and inverted mass hierarchy. As the case for the pure matter-induced neutrino oscillation (Mikheyev--Smirnov--Wolfenstein (MSW) effect), we find that the RSF transitions are strongly dependent on the neutrino mass hierarchy as well as the value of $\theta_{13}$. Flavour conversions are solved numerically for various neutrino parameter sets, with presupernova profile calculated by Woosley and Weaver. In particular, it is very interesting that the RSF-induced \nu_\rme\to\bar\nu_\rme transition occurs, if the following conditions are all satisfied: the value of $\mu_\nu B$ ($\mu_\nu$ is the neutrino magnetic moment, and $B$ is the magnetic field strength) is sufficiently strong, the neutrino mass hierarchy is inverted, and the value of $\theta_{13}$ is large enough to induce adiabatic MSW resonance. In this case, the strong peak due to original \nu_\rme emitted from neutronization burst would exist in time profile of the neutrino events detected at the Super-Kamiokande detector. If this peak were observed in reality, it would provide fruitful information on the neutrino properties. On the other hand, characters of the neutrino spectra are also different between the neutrino models, but we find that there remains degeneracy among several models. Dependence on presupernova models is also discussed.Comment: 23 pages, 11 figures, corrected minor typos, added references. Final version to appear in Journal of Cosmology and Astroparticle Physic

Supernova neutrinos in the light of FCNC

We study the effect of including flavor changing neutral currents (FCNC) in the analysis of the neutrino signal of a supernova burst. When we include the effect of the FCNC which are beyond the standard model (SM) in the study of the MSW resonant conversion, we obtain dramatic changes in the \Delta m^2-sin^2(2\theta) probability contours for neutrino detection.Comment: 8 pages in ReVTeX,3 figures. Revised manuscript submitted to Phys. Rev.

The electromagnetic vertex of neutrinos in an electron background and a magnetic field

We study the electromagnetic vertex function of a neutrino that propagates in an electron background in the presence of a static magnetic field. The structure of the vertex function under the stated conditions is determined and it is written down in terms of a minimal and complete set of tensors. The one-loop expressions for all the form factors is given, up to terms that are linear in the magnetic field, and the approximate integral formulas that hold in the long wavelength limit are obtained. We discuss the physical interpretation of some of the form factors and their relation with the concept of the neutrino induced charge. The neutrino acquires a longitudinal and a transverse charge, due to the fact that the form factors depend on the transverse and longitudinal components of the photon momentum independently. We compute those form factors explicitly in various limiting cases and find that the longitudinal and transverse charge are the same for the case of a non-relativistic electron gas, but not otherwise.Comment: 18 pages. Revtex4, axodra

Three-generation study of neutrino spin-flavor conversion in supernova and implication for neutrino magnetic moment

We investigate resonant spin-flavor (RSF) conversions of supernova neutrinos which are induced by the interaction of neutrino magnetic moment and supernova magnetic fields. From the formulation which includes all three-flavor neutrinos and anti-neutrinos, we give a new crossing diagram that includes not only ordinary MSW resonance but also magnetically-induced RSF effect. With the diagram, it is found that four conversions occur in supernova, two are induced by the RSF effect and two by the pure MSW. We also numerically calculate neutrino conversions in supernova matter, using neutrino mixing parameters inferred from recent experimental results and a realistic supernova progenitor model. The results indicate that until 0.5 seconds after core bounce, the RSF-induced $\bar{\nu}_e \leftrightarrow \nu_\tau$ transition occurs efficiently (adiabatic resonance), when \mu_\nu \agt 10^{-12} \mu_B (B_0 / 5 \times 10^{9} \mathrm G)^{-1}, where $B_0$ is the strength of the magnetic field at the surface of iron core. We also evaluate the energy spectrum as a function of $\mu_\nu B_0$ at the SuperKamiokande detector and the Sudbury Neutrino Observatory using the calculated conversion probabilities, and find that the spectral deformation might have possibility to provide useful information on neutrino magnetic moment as well as magnetic field strength in supernovae.Comment: 35 pages, 13 figure

Discriminating among Earth composition models using geo-antineutrinos

It has been estimated that the entire Earth generates heat corresponding to about 40 TW (equivalent to 10,000 nuclear power plants) which is considered to originate mainly from the radioactive decay of elements like U, Th and K, deposited in the crust and mantle of the Earth. Radioactivity of these elements produce not only heat but also antineutrinos (called geo-antineutrinos) which can be observed by terrestrial detectors. We investigate the possibility of discriminating among Earth composition models predicting different total radiogenic heat generation, by observing such geo-antineutrinos at Kamioka and Gran Sasso, assuming KamLAND and Borexino (type) detectors, respectively, at these places. By simulating the future geo-antineutrino data as well as reactor antineutrino background contributions, we try to establish to which extent we can discriminate among Earth composition models for given exposures (in units of kt$\cdot$ yr) at these two sites on our planet. We use also information on neutrino mixing parameters coming from solar neutrino data as well as KamLAND reactor antineutrino data, in order to estimate the number of geo-antineutrino induced events.Comment: 24 pages, 10 figures, final version to appear in JHE

Testing the Principle of Equivalence by Solar Neutrinos

We discuss the possibility of testing the principle of equivalence with solar neutrinos. If there exists a violation of the equivalence principle quarks and leptons with different flavors may not universally couple with gravity. The method we discuss employs a quantum mechanical phenomenon of neutrino oscillation to probe into the non-universality of the gravitational couplings of neutrinos. We develop an appropriate formalism to deal with neutrino propagation under the weak gravitational fields of the sun in the presence of the flavor mixing. We point out that solar neutrino observation by the next generation water Cherenkov detectors can improve the existing bound on violation of the equivalence principle by 3-4 orders of magnitude if the nonadiabatic Mikheyev-Smirnov-Wolfenstein mechanism is the solution to the solar neutrino problem.Comment: Latex, 17 pages + 6 uuencoded postscript figures, KEK-TH-396, TMUP-HEL-9402 (unnecessary one reference was removed

Neutrino Physics at the Turn of the Millenium

Recent solar & atmospheric nu-data strongly indicate need for physics beyond the Standard Model. I review the ways of reconciling them in terms of 3-nu oscillations. Though not implied by data, bi-maximal nu-mixing models emerge as a possibility. SUSY with broken R-parity provides an attractive way to incorporate it, opening the possibility of testing nu-anomalies at high- energy colliders such as the LHC or at the upcoming long-baseline or nu- factory experiments. Reconciling, in addition, the LSND hint requires a fourth, light sterile neutrino, nus. The simplest are the most symmetric scenarios, in which 2 of the 4 neutrinos are maximally-mixed and lie at the LSND scale, while the others are at the solar scale. The lightness of nus, the nearly maximal atmospheric mixing, and the solar/atmospheric splittings all follow naturally from the assumed lepton-number symmetry and its breaking. These basic schemes can be distinguished at neutral-current-sensitive solar & atmospheric neutrino experiments such as SNO. However underground experiments have not yet proven neutrino masses, as there are many alternatives. For example flavour changing interactions can play an important role in the explanation of solar and contained atmospheric data and could be tested e.g through \mu \to e + \gamma, \mu-e conversion in nuclei, unaccompanied by neutrino-less double beta decay. Conversely, a short-lived numu might play a role in the explanation of the atmospheric data. Finally, in the presence of a nus, a long-lived heavy nutau could delay the time at which the matter and radiation contributions to the energy density of the Universe become equal, reducing density fluctuations on smaller scales, thus saving the standard CDM scenario, while the light nue, numu and nus would explain the solar & atmospheric data.Comment: Invited talk at 2nd International Conference on Non-Accelerator New Physics (NANP-99), Dubna, June 28 - July 3, 199

Finite dimensional systems with random external fields and Neutrino propagation in fluctuating media

We develop the general formalism for the study of neutrino propagation in presence of stochastic media. This formalism allows the systematic derivation of evolution equations for averaged quantities as survival probabilities and higher order distribution moments. The formalism applies equally to any finite dimensional Schroedinger equation in presence of a stochastic external force. New integro-differential equations valid for finite correlated processes are obtained for the first time. For the particular case of exponentially correlated processes a second order ordinary equation is obtained. As a consequence, the Redfield equation valid for Gaussian delta-correlated noise is rederived in a simple way. The formalism, together with the quantum correlation theorem is applied to the computation of higher moments and correlation functions of practical interest in forthcoming high precision neutrino experiments. It is shown that equal and not equal time correlators follow similar differential equations.Comment: 12 pags., Latex. 1 fig., ps. epsfig macro. minor typo errors correcte