119457636
Splitting of the pi-rho spectrum in a renormalized light-cone QCD-inspired model
We show that the splitting between the light pseudoscalar and vector meson states is due to the strong short-range attraction in the ${}^{1}{S}_{0}$ sector which makes the pion and the kaon light particles. We use a light-cone QCD-inspired model of the mass squared operator with harmonic confinement and a Dirac-delta interaction. We apply a renormalization method to define the model, in which the pseudoscalar ground state mass fixes the renormalized strength of the Dirac-delta interaction.
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.
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.
118563627
DEFORMED RELATIVISTIC HARTREE-BOGOLIUBOV MODEL FOR EXOTIC NUCLEI
A deformed relativistic Hartree-Bogoliubov (DRHB) model is developed aiming at a proper description of exotic nuclei, particularly deformed ones with large spatial extension. In order to give an adequate description of both the contribution of the continuum and the large spatial distribution in exotic nuclei, the DRHB equations are solved in a Woods-Saxon basis in which the radial wave functions have proper asymptotic behaviors at large distance from the nuclear center which is crucial for the formation of halo. The formalism and the numerical procedure of the DRHB model in a Woods-Saxon basis are briefly presented.
18203445
Theoretical study of the two-proton halo candidate 17Ne including contributions from resonant continuum and pairing correlations
Abstract.With the relativistic Coulomb wave function boundary condition, the energies, widths and wave functions of the single-proton resonant orbitals for 17Ne are studied by the analytical continuation in the coupling constant (ACCC) approach within the framework of the relativistic mean field (RMF) theory. Pairing correlations and contributions from the single-particle resonant orbitals in the continuum are taken into consideration by the resonant Bardeen-Cooper-Schrieffer (BCS) approach, in which the constant pairing strength is used. It can be seen that the fully self-consistent calculations with NL3 and NLSH effective interactions mostly agree with the latest experimental measurements, such as binding energies, matter radii, charge radii and densities. The energy of the $ \pi2s_{1/2}$ orbital is slightly higher than that of the $ \pi1d_{5/2}$ orbital, and the occupation probability of the $ (\pi2s_{1/2})^2$ orbital is about 20%, which is in accordance with the shell model calculation and three-body model estimation.
119477279
Pseudospin symmetry and its approximation in real nuclei
The origin of pseudospin symmetry and its broken in real nuclei are discussed in the relativistic mean field theory. In the exact pseudospin symmetry, even the usual intruder orbits have degenerate partners. In real nuclei, pseudospin symmetry is approximate, and the partners of the usual intruder orbits will disappear. The difference is mainly due to the pseudo spin-orbit potential and the transition between them is discussed in details. The contribution of pseudospin-orbit potential for intruder orbits is quite large, compared with that for pseudospin doublets. The disappearance of the pseudospin partner for the intruder orbit can be understood from the properties of its wave function.
12995113
Possible deviation from the tri-bimaximal neutrino mixing in a seesaw model
We propose a simple but suggestive seesaw model with two phenomenological conjectures: three heavy (right-handed) Majorana neutrinos are degenerate in mass in the symmetry limit and three light Majorana neutrinos have the tri-bimaximal mixing pattern ${V}_{0}$. We show that a small mass splitting between the first generation and the other two generations of heavy Majorana neutrinos is responsible for the deviation of the solar neutrino mixing angle ${\ensuremath{\theta}}_{12}$ from its initial value $35.3\ifmmode^\circ\else\textdegree\fi{}$ given by ${V}_{0}$, and the slight breaking of the mass degeneracy between the second and third generations of heavy Majorana neutrinos results in a small mixing angle ${\ensuremath{\theta}}_{13}$ and a tiny departure of the atmospheric neutrino mixing angle ${\ensuremath{\theta}}_{23}$ from $45\ifmmode^\circ\else\textdegree\fi{}$. It turns out that a normal hierarchy of the light neutrino mass spectrum is favored in this seesaw scenario.
119226033
Impacts of the Higgs mass on vacuum stability, running fermion masses and two-body Higgs decays
The recent results of the ATLAS and CMS experiments indicate 116 GeV less than or similar to M-H less than or similar to 131 GeV and 115 GeV less than or similar to M-H less than or similar to 127 GeV, respectively, for the mass of the Higgs boson in the standard model (SM) at the 95% confidence level. In particular, both experiments point to a preferred narrow mass range M-H similar or equal to (124 . . . 126) GeV. We examine the impact of this preliminary result of M-H on the SM vacuum stability by using the two-loop renormalization-group equations, and arrive at the cutoff scale Lambda(VS) similar to 4 X 10(12) GeV (for M-H = 125 GeV, M-t = 172.9 GeV, and alpha(s)(M-Z) = 0.1184), where the absolute stability of the SM vacuum is lost and some kind of new physics might take effect. We update the values of running lepton and quark masses at some typical energy scales, including the ones characterized by M-H, 1 TeV and Lambda(VS), with the help of the two-loop renormalization-group equations. The branching ratios of some important two-body Higgs decay modes, such as H -> b (b) over bar, H -> tau(+)tau(-), H -> gamma gamma, H -> W+W-, and H -> ZZ, are also recalculated by inputting the values of relevant particle masses at M-H.
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.
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.
118506210
Testing the realistic seesaw model with two heavy Majorana neutrinos at the CERN Large Hadron Collider
In the conventional type-(I+II) seesaw model, the effective mass matrix of three known light neutrinos is given by M(v) = M(L) - M(D)M(R)(-1)M(D)(T) in the leading-order approximation. We propose an intriguing scenario, in which the structural cancellation condition M(D)M(R)(-1)M(D)(T) = 0 is guaranteed by the A(4) x Z(2) flavor symmetry. As a consequence, neutrino masses are mainly generated by the Higgs triplet M(v) = M(L), while the neutrino mixing matrix is non-unitary and takes on the nearly tri-bimaximal pattern. A discriminating feature of this scenario from the pure type-II seesaw model is that the lepton-number-violating signatures induced by the heavy Majorana neutrinos can be discovered at the CERN Large Hadron Collider. We calculate the total cross section of the same-sign dilepton events pp -> l(alpha)(+/-)N(i) -> l(alpha)(+/-)l(beta)(+/-)jj (for i = 1, 2 and alpha, beta = e, mu, tau), and emphasize the significant interference of the contributions from two different heavy Majorana neutrinos. The background from the standard model and the kinematic cuts used to reduce it have been considered. The possible way to distinguish between the signals from heavy Majorana neutrinos and those from doubly-charged Higgs bosons is briefly discussed. (C) 2009 Elsevier B.V. All rights reserved.