Power-law cosmological solution derived from DGP brane with a brane tachyon field

By studying a tachyon field on the DGP brane model, in order to embed the 4D standard Friedmann equation with a brane tachyon field in 5D bulk, the metric of the 5D spacetime is presented. Then, adopting the inverse square potential of tachyon field, we obtain an expanding universe with power-law on the brane and an exact 5D solution.Comment: 8 pages, 1 figure, accepted by IJMP

Orbital magnetization and its effect in antiferromagnets on the distorted fcc lattice

We study the intrinsic orbital magnetization (OM) in antiferromagnets on the distorted face-centered-cubic lattice. The combined lattice distortion and spin frustration induce nontrivial $k$-space Chern invariant, which turns to result in profound effects on the OM properties. We derive a specific relation between the OM and the Hall conductivity, according to which it is found that the intrinsic OM vanishes when the electron chemical potential lies in the Mott gap. The distinct behavior of the intrinsic OM in the metallic and insulating regions is shown. The Berry phase effects on the thermoelectric transport is also discussed.Comment: 18 pages, 6 figure

Competition policy under laissez-faireism : market power and its treatment in Hong Kong

The paper describes the current competition policy framework in Hong Kong: how it came into existence, what business practices are prohibited, and how the enforcement system works. Recent cases in the telecommunications industry are used to illustrate the sectoral approach, the unique feature of Hong Kong’s competition policy. The paper argues that a sectoral approach faces two fundamental drawbacks. First, due to having different “rules of the game” for different sectors, the allocation of resources may be distorted in the long run. Second, since the relevant regulatory agencies perform dual roles both as competition policy enforcer and as traditional regulator of natural monopolies, the impartiality of their competition decisions may not be credibly conveyed to the general public. We also address other specific problems associated with the current sectoral approach, such as the exclusion of structural issues, narrow coverage of sectors, and the lack of public enforcement. An overall competition law can better promote competition and economic efficiency in Hong Kong

Period halving of Persistent Currents in Mesoscopic Mobius ladders

We investigate the period halving of persistent currents(PCs) of non-interacting electrons in isolated mesoscopic M\"{o}bius ladders without disorder, pierced by Aharonov-Bhom flux. The mechanisms of the period halving effect depend on the parity of the number of electrons as well as on the interchain hopping. Although the data of PCs in mesoscopic systems are sample-specific, some simple rules are found in the canonical ensemble average, such as all the odd harmonics of the PCs disappear, and the signals of even harmonics are non-negative. {PACS number(s): 73.23.Ra, 73.23.-b, 68.65.-k}Comment: 6 Pages with 3 EPS figure

Dynamical study of the light scalar mesons below 1 GeV in a flux-tube model

The light scalar mesons below 1 GeV as tetraquark states are studied in the framework of the flux-tube model, the multi-body confinement instead of the additive two-body confinement is used. From the calculated results, we find that the light scalar mesons, $\sigma$, $\kappa$ could be well accommodated in the diquark-antidiquark tetraquark picture in the flux-tube model and they could be color confinement resonances. The mass of the first radial excited state of $[ud][\bar{u}\bar{d}]$ is 1019 MeV, which is close to the mass of $f_0(980)$. Whereas $a_0(980)$ can not be fitted in this interpretation.Comment: 11 pages, 1 figur

Suppression of ferromagnetic spin fluctuations in the filled skutterudite superconductor SrOs4 As12 revealed by 75As NMR-NQR measurements

Motivated by the recent observation of ferromagnetic spin correlations in the filled skutterudite SrFe4As12 [Q.-P. Ding et al., Phys. Rev. B 98, 155149 (2018)], we have carried out As-75 nuclear magnetic resonance (NMR) and nuclear quadrupole resonance (NQR) measurements to investigate the role of magnetic fluctuations in the newly discovered isostructural superconductor SrOs4As12 with a superconducting transition temperature of T-c similar to 4.8 K. Knight shift K determined by the NQR spectrum under a small magnetic field (\u3c= 0.5 T) is nearly independent of temperature, consistent with the temperature dependence of the magnetic susceptibility. The nuclear spin-lattice relaxation rate divided by temperature, 1/T1T, is nearly independent of temperature above similar to 50 K and increases slightly with decreasing temperature below the temperature. The temperature dependence is reasonably explained by a simple model where a flat band structure with a small ledge near the Fermi energy is assumed. By comparing the present NMR data with those in SrFe4As12, we found that the values of vertical bar K vertical bar and 1/T1T in SrOs4As12 are smaller than those in SrFe4As12, indicating no obvious ferromagnetic spin correlations in SrOs4As12. From the temperature dependence of 1/T-1 in the superconducting state, an s-wave superconductivity is realized