119191185
Effects of tensor interaction on pseudospin energy splitting and shell correction
In the framework of a Skyrme-Hartree-Fock approach combined with Bardeen-Cooper-Schrieffer (BCS) method, the role of the tensor force on the pseudospin energy splitting for tin isotope chain is investigated. The tensor force turns out to obviously affect the pseudospin energy splitting of the spin-unsaturated nuclei. Since the tensor force shifts the single-particle levels, it modifies the single-particle level density and the shell correction energy thereof. The influence of the tensor interaction on shell correction energy is considerable according to our analysis taking a magic nucleus {sup 132}Sn as well as a superheavy nucleus {sup 298}114 as examples. This modification of the shell correction energy due to the tensor component affects the stability of the superheavy nuclei.
99483196
Correlation between muonic levels and nuclear structure in muonic atoms
Abstract A method that deals with the nucleons and the muon unitedly is employed to investigate the muonic lead, with which the correlation between the muon and nucleus can be studied distinctly. A “kink” appears in the muonic isotope shift at a neutron magic number where the nuclear shell structure plays a key role. This behavior may have very important implications for the experimentally probing the shell structure of the nuclei far away from the β -stable line. We investigate the variations of the nuclear structure due to the interaction with the muon in the muonic atom and find that the nuclear structure remains basically unaltered. Therefore, the muon is a clean and reliable probe for studying the nuclear structure. In addition, a correction that the muon-induced slight change in the proton density distribution in turn shifts the muonic levels is investigated. This correction to muonic level is as important as the Lamb shift and high order vacuum polarization correction, but is larger than anomalous magnetic moment and electron shielding correction.
119932492
Fine structure of alpha decay to rotational states of heavy nuclei
To gain a better insight into alpha-decay fine structure, we calculate the relative intensities of alpha decay to 2{sup +} and 4{sup +} rotational states in the framework of the generalized liquid drop model (GLDM) and improved Royer's formula. The calculated relative intensities of alpha decay to 2{sup +} states are in good agreement with the experimental data. For the relative intensities of alpha decay to 4{sup +} states, a good agreement with experimental data is achieved for Th and U isotopes. The formula we obtain is useful for the analysis of experimental data of alpha-decay fine structure. In addition, some predicted relative intensities which are still not measured are provided for future experiments.
14695790
String Gas Cosmology and Non-Gaussianities
Recently it has been shown that string gas cosmology, an alternative model of the very early universe which does not involve a period of cosmological inflation, can give rise to an almost scale invariant spectrum of metric perturbations. Here we calculate the non-Gaussianities of the spectrum of cosmological fluctuations in string gas cosmology, and find that these non-Gaussianities depend linearly on the wave number and that their amplitude depends sensitively on the string scale. If the string scale is at the TeV scale, string gas cosmology could lead to observable non-Gaussianities, if it is close to the Planck scale, then the non-Gaussianities on current cosmological scales are negligible.
39616698
Fermionic zero modes in gauge and gravity backgrounds on T-2
Here we study fermionic zero modes in gauge and gravity backgrounds taking a two-dimensional compact manifold T-2 as extra dimensions. The result is that there exist massless Dirac fermions which have normalizable zero modes under quite general assumptions about these backgrounds on the bulk. Several special cases of gauge background on the torus are discussed and some simple fermionic zero modes axe obtained.
519528
Inflation with Holographic Dark Energy
We investigate the corrections of the holographic dark energy to inflation paradigm. We study the evolution of the holographic dark energy in the inflationary universe in detail, and carry out a model - independent analysis on the holographic dark energy corrections to the primordial scalar power spectrum. It turns out that the corrections generically make the spectrum redder. To be consistent with the experimental data, there must be a upper bound on the reheating temperature. We also discuss the corrections due to different choices of the infrared cutoff. (c) 2007 Elsevier B.V. All rights reserved.
119247594
Investigate the interaction between dark matter and dark energy
In this paper we investigate the interaction between dark matter and dark energy by considering two different interacting scenarios, i.e. the cases of constant interaction function and variable interaction function. By fitting the current observational data to constrain the interacting models, it is found that the interacting strength is non-vanishing, but weak for the case of constant interaction function, and the interaction is not obvious for the case of variable interaction function. In addition, for seeing the influence from interaction we also investigate the evolutions of interaction function, effective state parameter for dark energy and energy density of dark matter. At last some geometrical quantities in the interacting scenarios are discussed.
119448285
Prospects for constraining cosmology with the extragalactic cosmic microwave background temperature
Observers have demonstrated that it is now feasible to measure the cosmic microwave background (CMB) temperature at high redshifts. We explore the possible constraints on cosmology which might ultimately be derived from such measurements. In addition to providing a consistency check on standard and alternative cosmologies, possibilities include constraints on the inhomogeneity and anisotropy of the universe at intermediate redshift $z\ensuremath{\lesssim}10,$ an independent probe of peculiar motions with respect to the Hubble flow, constraining the epoch of reionization, and the time variability of the fine structure constant. We argue that the best possibility is as a probe of peculiar motions. We show, however, that the current measurement uncertainty $(\ensuremath{\Delta}T=\ifmmode\pm\else\textpm\fi{}0.002\mathrm{K})$ in the local present absolute CMB temperature imposes intrinsic limits on the use of such CMB temperature measurements as a cosmological probe. At best, anisotropies at intermediate redshift could only be constrained at a level of $\ensuremath{\gtrsim}0.1%$ and peculiar motions could only be determined to an uncertainty of $\ensuremath{\gtrsim}311{\mathrm{km}\mathrm{}\mathrm{}\mathrm{s}}^{\ensuremath{-}1}.$ If the high z CMB temperature can only be measured with a precision comparable to the uncertainty of the local interstellar CMB temperature, then peculiar motions could be determined to an uncertainty of ${1101(1+z)}^{\ensuremath{-}1}[\ensuremath{\Delta}{T}_{\mathrm{CMB}}(z)/0.01\mathrm{K}]{\mathrm{km}\mathrm{}\mathrm{s}}^{\ensuremath{-}1}.$