Energy Spectrum and Phase Transition of Superfluid Fermi Gas of Atoms on Noncommutative Space

Based on the Bogoliubov non-ideal gas model, we discuss the energy spectrum and phase transition of the superfluid Fermi gas of atoms with a weak attractive interaction on the canonical noncommutative space. Because the interaction of a BCS-type superfluid Fermi gas originates from a pair of Fermionic quasi-particles with opposite momenta and spins, the Hamiltonian of the Fermi gas on the noncommutative space can be described in terms of the ordinary creation and annihilation operators related to the commutative space, while the noncommutative effect appears only in the coefficients of the interacting Hamiltonian. As a result, we can rigorously solve the energy spectrum of the Fermi gas on the noncommutative space exactly following the way adopted on the commutative space without the use of perturbation theory. In particular, different from the previous results on the noncommutative degenerate electron gas and superconductor where only the first order corrections of the ground state energy level and energy gap were derived, we obtain the nonperturbative energy spectrum for the noncommutative superfluid Fermi gas, and find that each energy level contains a corrected factor of cosine function of noncommutative parameters. In addition, our result shows that the energy gap becomes narrow and the critical temperature of phase transition from a superfluid state to an ordinary fluid state decreases when compared with that in the commutative case

Transport Exponents of Sturmian Hamiltonians

We consider discrete Schr\"odinger operators with Sturmian potentials and study the transport exponents associated with them. Under suitable assumptions on the frequency, we establish upper and lower bounds for the upper transport exponents. As an application of these bounds, we identify the large coupling asymptotics of the upper transport exponents for frequencies of constant type. We also bound the large coupling asymptotics uniformly from above for Lebesgue-typical frequency. A particular consequence of these results is that for most frequencies of constant type, transport is faster than for Lebesgue almost every frequency. We also show quasi-ballistic transport for all coupling constants, generic frequencies, and suitable phases.Comment: 30 page

Asteroseismology of DAV white dwarf stars and G29-38

Asteroseismology is a powerful tool to detect the inner structure of stars. It is also widely used to study white dwarfs. In this paper, we discuss the asteroseismology work of DAV stars. The detailed period to period fitting method is fully discussed, including the reliability to detect the inner structure of DAV stars. If we assume that all observed modes of some DAV star are the $l$ = 1 ones, the errors of model fitting will be always great. If we assume that the observed modes are composed of $l$ = 1 and 2 modes, the errors of model fitting will be small. However, there will be modes identified as $l$ = 2 without quintuplets observed. G29-38 has been observed spectroscopically and photometrically for many years. Thompson et al. (2008) made $l$ identifications for the star through limb darkening effect. With eleven known $l$ modes, we also do the asteroseismology work for G29-38, which reduces the blind $l$ fittings and is a fair choice. Unfortunately, our two best-fitting models are not in line with the previous atmospheric results. Based on factors of only a few modes observed, stability and identification of eigenmodes, identification of spherical degrees, construction of physical and realistic models and so on, detecting the inner structure of DAV stars by asteroseismology needs further development.Comment: 7pages, 1figur

The 3G standard setting strategy and indigenous innovation policy in China is TD-SCDMA a flagship?

In the time of “network economy”, industries and the public have stressed several “battles for dominance” between two or more rival technologies, often involving well-known firms operating in highly visible industries. In this paper, we are going to focus on the Chinese self-developed standard TD-SCDMA to perceive the implication and target of the nation’s policy and strategy. The motivation of the research starts from the interesting fact we observed: TD-SCDMA is named as the Chinese made standard, however the Chinese hold core patent technology is still about 7%, while most of the rest part is still taken by other foreign companies. The “faultage” between the small share reality and a self made standard sweet dream implies a well plotted strategy. In order to understand it, we firstly raise the question of why the Chinese government postpones the 3G decision again and again. Then we go further to probe why the standard-setting of TD-SCDMA has aroused wide attention as a strategic tool to fulfill “indigenous innovation”, and finally becomes part of national science and technology policy to increase international competitiveness? We are going to use economics theories to understand the essence of the creation of TD-SCDMA, and its relation to China’s interests.3G, standard, innovation, China

Radially Excited States of ηc\eta_c

In the framework of chiral quark model, the mass spectrum of $\eta_c(ns) (n=1,...,6)$ is studied with Gaussian expansion method. With the wave functions obtained in the study of mass spectrum, the open flavor two-body strong decay widths are calculated by using $^3P_0$ model. The results show that the masses of $\eta_c(1S)$ and $\eta_c(2S)$ are consistent with the experimental data. The explanation of X(3940) as $\eta_c(3S)$ is disfavored for X(3940) is a narrow state, $\Gamma=37^{+26}_{-15} \pm 8$ MeV, while the open flavor two-body strong decay width of $\eta_c(3S)$ is about 200 MeV in our calculation. Although the mass of X(4160) is about 100 MeV less than that of $\eta_c(4S)$, the assignment of X(4160) as $\eta_c(4S)$ can not be excluded because the open flavor two-body strong decay width of $\eta_c(4S)$ is consistent with the experimental value of X(4160) and the branching ratios of $\eta_c(4S)$ are compatible with that of X(4160), and the mass of $\eta_c(4S)$ can be shifted downwards by taking into account the coupling effect of the open charm channels. There are still no good candidates to $\eta_c(5S)$ and $\eta_c(6S)$.Comment: 5 page