15746471
Neutrino decays and neutrino-electron elastic scattering in unparticle physics
Following Georgi's unparticle scheme, we examine the effective couplings between neutrinos and unparticle operators. As an immediate consequence, neutrinos become unstable and can decay into the unparticle stuff. Assuming the dimension transmutation scale is around Lambda(u) - 1 TeV, we implement the cosmological limit on the neutrino lifetime to constrain the neutrino-unparticle couplings for different scaling dimensions d. In addition, provided that the electron-unparticle coupling is restricted due to the precise measurement of the anomalous magnetic moment of electron, we calculate the unparticle contribution to the neutrino-electron elastic scattering. It is more important to jointly deal with the couplings of the unparticle to the standard model particles rather than separately. Taking into account both electron- and neutrino-unparticle couplings, we find that the scaling dimension of the scalar unparticle should lie in the narrow range 1 < d < 2 by requiring the observables to be physically meaningful. However, there is no consistent range of d for the vector unparticle operator. (C) 2007 Elsevier B.V. All rights reserved.
118483859
The Minimal Seesaw Model at the TeV Scale
We point out that the minimal seesaw model can provide a natural framework to accommodate tiny neutrino masses, while its experimental testability and notable predictiveness are still maintained. T ...
15493650
Why is the 3 x 3 neutrino mixing matrix almost unitary in realistic seesaw models
A simple extension of the standard model is to introduce n heavy right-handed Majorana, neutrinos and preserve its SU(2)(L) X U(1)(Y) gauge symmetry. Diagonalizing the (3 + n) x (3 + n) neutrino mass matrix, we obtain an exact analytical expression for the effective mass matrix of nu(e), nu(mu) and nu(tau). It turns out that the 3 x 3 neutrino mixing matrix V, which appears in the leptonic charged-current weak interactions, must not be exactly unitary. The unitarity violation of V is negligibly tiny, however, if the canonical seesaw mechanism works to reproduce the correct mass scale of light Majorana neutrinos. A similar conclusion can be drawn in the. realistic Type-II seesaw models.
119195344
The Minimal Type-II Seesaw Model and Flavor-dependent Leptogenesis
In this talk, we first give a brief review of the so-called minimal seesaw models and then concentrate on the minimal type-I seesaw model with two almost degenerate right-handed Majorana neutrinos of $\mathcal{O}(1 \,{\rm TeV})$. A specific texture of the neutrino Yukawa coupling matrix is proposed to achieve the nearly tri-bimaximal neutrino mixing pattern. This ansatz predicts (1) θ23 = π/4, |δ| = π/2 and sin2θ12 = (1 − 2tan2θ13)/3 in the m1 = 0 case; and (2) θ23 = π/4 and θ13 = 8 = 0 in the m3 = 0 case. In both cases, the cosmological baryon number asymmetry can be explained via the resonant leptogenesis mechanism. Finally, we demonstrate the significance of flavor-dependent effects in our leptogenesis scenario.
118709874
Neutrinos in Particle Physics, Astronomy and Cosmology
Neutrinos: Past, Present and Future.- Neutrinos within the Standard Model.- Neutrinos beyond the Standard Model.- Phenomenology of Neutrino Oscillations.- Neutrinos from Stars.- Neutrinos from Supernovae.- Ultrahigh Energy Cosmic Neutrinos.- Neutrinos and Big Bang Nucleosynthesis.- Neutrinos and Cosmological Perburbations.- Neutrinos and Matter-Antimatter Asymmetry.- Other Topics of Neutrino Astrophysics.
119499848
Minimal type II seesaw model
We propose a minimal type II seesaw model by introducing only one right-handed neutrino besides the SU(2){sub L} triplet Higgs to the standard model. In the usual type II seesaw models with several right-handed neutrinos, the contributions of the right-handed neutrinos and the triplet Higgs to the CP asymmetry, which stems from the decay of the lightest right-handed neutrino, are proportional to their respective contributions to the light neutrino mass matrix. However, in our minimal type II seesaw model, this CP asymmetry is just given by the one-loop vertex correction involving the triplet Higgs, even though the contribution of the triplet Higgs does not dominate the light neutrino masses. For illustration, the Fritzsch-type lepton mass matrices are considered.
17321794
Relativistic continuum Hartree Bogoliubov theory for ground-state properties of exotic nuclei
The Relativistic Continuum Hartree-Bogoliubov (RCHB) theory, which properly takes into account the pairing correlation and the coupling to (discretized) continuum via Bogoliubov transformation in a microscopic and self-consistent way, has been reviewed together with its new interpretation of the halo phenomena observed in light nuclei as the scattering of particle pairs into the continuum, the prediction of the exotic phenomena - giant halos in nuclei near neutron drip line, the reproduction of interaction cross sections and charge-changing cross sections in light exotic nuclei in combination with the Glauber theory, better restoration of pseudo-spin symmetry in exotic nuclei, predictions of exotic phenomena in hypernuclei, and new magic numbers in superheavy nuclei, etc. Recent investigations on new effective interactions, the density dependence of the interaction strengths, the RMF theory on the Woods-Saxon basis, the single-particle resonant states, and the resonant BCS (rBCS) method for the pairing correlation, etc. are also presented in some detail. (c) 2005 Elsevier B.V. All rights reserved.
119300578
Neutron halo in deformed nuclei from a relativistic Hartree-Bogoliubov model in a Woods-Saxon basis
Halo phenomenon in deformed nuclei is studied by using a fully self-consistent deformed relativistic Hartree-Bogoliubov model in a spherical Woods-Saxon basis with the proper asymptotic behavior at large distance from the nuclear center. Taking a deformed neutron-rich and weakly bound nucleus 44Mg as an example and by examining contributions of the halo, deformation effects, and large spatial extensions, we show a decoupling of the halo orbitals from the deformation of the core.
55849801
Generalized massive gravity in arbitrary dimensions and its Hamiltonian formulation
We extend the four-dimensional de Rham-Gabadadze-Tolley (dRGT) massive gravity model to a general scalar massive-tensor theory in arbitrary dimensions, coupling a dRGT massive graviton to multiple scalars and allowing for generic kinetic and mass matrix mixing between the massive graviton and the scalars, and derive its Hamiltonian formulation and associated constraint system. When passing to the Hamiltonian formulation, two different sectors arise: a general sector and a special sector. Although obtained via, different ways, there are two second class constraints in either of the two sectors, eliminating the BD ghost. However, for the special sector, there are still ghost instabilities except for the case of two dimensions. In particular, for the special sector with one scalar, there is a "second BD ghost".
119288312
Galileons with Gauge Symmetries
Galileon models arise in certain braneworld scenarios as modifications to General Relativity, and are also interesting as field theories in their own right. We show how the galileon model can be naturally generalized to include local gauge symmetries, by allowing for couplings to Yang-Mills fields. The resulting theories have at most second order spacetime derivatives in any representation of the gauge group, thereby avoiding Ostrogradski ghosts. We also extend the models to include curved space, and show how in that case we need to include non-minimal couplings between the galileons and the curvature tensors for the theory to retain its second order nature.
119220585
Systematic investigation of the rotational bands in nuclei with Z approximate to 100 using a particle-number conserving method based on a cranked shell model
The rotational bands in nuclei with Z approximate to 100 are investigated systematically by using a cranked shell model (CSM) with the pairing correlations treated by a particle-number conserving (PNC) method, in which the blocking effects are taken into account exactly. By fitting the experimental single-particle spectra in these nuclei, a new set of Nilsson parameters (kappa and mu) and deformation parameters (epsilon(2) and epsilon(4)) are proposed. The experimental kinematic moments of inertia for the rotational bands in even-even, odd-A, and odd-odd nuclei, and the band-head energies of the one-quasiparticle bands in odd-A nuclei, are reproduced quite well by the PNC-CSM calculations. By analyzing the omega dependence of the occupation probability of each cranked Nilsson orbital near the Fermi surface and the contributions of valence orbitals in each major shell to the angular momentum alignment, the upbending mechanism in this region is understood clearly.