121823192
Neutron halos in hypernuclei
Abstract:Properties of single- Λ and double- Λ hypernuclei for even-N Ca isotopes ranging from the proton dripline to the neutron dripline are studied using the relativistic continuum Hartree-Bogoliubov theory with a zero-range pairing interaction. Compared with ordinary nuclei, the addition of one or two Λ-hyperons lowers the Fermi level. The predicted neutron dripline nuclei are, respectively, 75ΛCa and 762ΛCa, as the additional attractive force provided by the Λ-N interaction shifts nuclei from outside to inside the dripline. Therefore, the last bound hypernuclei have two more neutrons than the corresponding ordinary nuclei. Based on the analysis of two-neutron separation energies, neutron single-particle energy levels, the contribution of continuum and nucleon density distribution, giant halo phenomena due to the pairing correlation, and the contribution from the continuum are suggested to exist in Ca hypernuclei similar to those that appear in ordinary Ca isotopes.
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.
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.
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.
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.
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.
119301979
Bi-galileon theory I: motivation and formulation
We introduce bi-galileon theory, the generalisation of the single galileon model introduced by Nicolis et al. The theory contains two coupled scalar fields and is described by a Lagrangian that is invariant under Galilean shifts in those fields. This paper is the first of two, and focuses on the motivation and formulation of the theory. We show that the boundary effective theory of the cascading cosmology model corresponds to a bi-galileon theory in the decoupling limit, and argue that this is to be expected for co-dimension 2 braneworld models exhibiting infra-red modification of gravity. We then generalise this, by constructing the most general bi-galileon Lagrangian. By coupling one of the galileons to the energy-momentum tensor, we pitch this as a modified gravity theory in which the modifications to General Relativity are encoded in the dynamics of the two galileons. We initiate a study of phenomenology by looking at maximally symmetric vacua and their stability, developing elegant geometric techniques that trivially explain why some of the vacua have to be unstable in certain cases (eg DGP). A detailed study of phenomenology appears in our companion paper.
26671710
Constraining absolute neutrino masses via detection of galactic supernova neutrinos at JUNO
A high-statistics measurement of the neutrinos from a galactic core-collapse supernova is extremely important for understanding the explosion mechanism, and studying the intrinsic properties of neutrinos themselves. In this paper, we explore the possibility to constrain the absolute scale of neutrino masses m(v) via the detection of galactic supernova neutrinos at the Jiangmen Underground Neutrino Observatory (JUNO) with a 20 kiloton liquid-scintillator detector. In assumption of a nearly-degenerate neutrino mass spectrum and a normal mass ordering, the upper bound on the absolute neutrino mass is found to be m(v) < (0.83 +/- 0.24) eV at the 95% confidence level for a typical galactic supernova at a distance of 10 kpc, where the mean value and standard deviation are shown to account for statistical fluctuations. For comparison, we find that the bound in the Super-Kamiokande experiment is m(v) < (0.91 +/- 0.28) eV at the same confidence level. However, the upper bound will be relaxed when the model parameters characterizing the time structure of supernova, neutrino fluxes are not exactly known, and when the neutrino mass ordering is inverted.
118418835
Mass-varying massive gravity
It has recently been shown that the graviton can consistently gain a constant mass without introducing the Boulware-Deser ghost. We propose a gravity model where the graviton mass is set by a scalar field and prove that this model is free of the Boulware-Deser ghost by analyzing its constraint system and showing that two constraints arise. We also initiate the study of the model's cosmic background evolution and tentatively discuss possible cosmological implications of this model. In particular, we consider a simple scenario where the scalar field setting the graviton mass is identified with the inflaton and the graviton mass evolves from a high to a low energy scale, giving rise to the current cosmic acceleration.
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.
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".