Electric Dipole Moments in the Generic Supersymmetric Standard Model

The generic supersymmetric standard model is a model built from a supersymmetrized standard model field spectrum the gauge symmetries only. The popular minimal supersymmetric standard model differs from the generic version in having R-parity imposed by hand. We review an efficient formulation of the model and some of the recently obtained interesting phenomenological features, focusing on one-loop contributions to fermion electric dipole moments.Comment: 1+7 pages Revtex 3 figures incoporated; talk at NANP'0

In an Attempt to Introduce Long-range Interactions into Small-world Networks

Distinguishing the long-range bonds with the regular ones, the critical temperature of the spin-lattice Guassian model built on two typical Small-world Networks (SWNs) is studied. The results show much difference from the classical case, and thus may induce some more accurate discussion on the critical properties of the spin-lattice systems combined with the SWNs.Comment: 4 pages, 3 figures, 18 referenc

On the afterglow from the receding jet of gamma-ray burst

According to popular progenitor models of gamma-ray bursts, twin jets should be launched by the central engine, with a forward jet moving toward the observer and a receding jet (or the counter jet) moving backwardly. However, in calculating the afterglows, usually only the emission from the forward jet is considered. Here we present a detailed numerical study on the afterglow from the receding jet. Our calculation is based on a generic dynamical description, and includes some delicate ingredients such as the effect of the equal arrival time surface. It is found that the emission from the receding jet is generally rather weak. In radio bands, it usually peaks at a time of $t \geq 1000$ d, with the peak flux nearly 4 orders of magnitude lower than the peak flux of the forward jet. Also, it usually manifests as a short plateau in the total afterglow light curve, but not as an obvious rebrightening as once expected. In optical bands, the contribution from the receding jet is even weaker, with the peak flux being $\sim 8$ orders of magnitude lower than the peak flux of the forward jet. We thus argue that the emission from the receding jet is very difficult to detect. However, in some special cases, i.e., when the circum-burst medium density is very high, or if the parameters of the receding jet is quite different from those of the forward jet, the emission from the receding jet can be significantly enhanced and may still emerge as a marked rebrightening. We suggest that the search for receding jet emission should mostly concentrate on nearby gamma-ray bursts, and the observation campaign should last for at least several hundred days for each event.Comment: A few citations added, together with a few minor revisions, main conclusions unchanged, accepted for publication in A&A, 7 figures, 10 Page

Phase diagrams of XXZ model on depleted square lattice

Using quantum Monte Carlo (QMC) simulations and a mean field (MF) theory, we investigate the spin-1/2 XXZ model with nearest neighbor interactions on a periodic depleted square lattice. In particular, we present results for 1/4 depleted lattice in an applied magnetic field and investigate the effect of depletion on the ground state. The ground state phase diagram is found to include an antiferromagnetic (AF) phase of magnetization $m_{z}=\pm 1/6$ and an in-plane ferromagnetic (FM) phase with finite spin stiffness. The agreement between the QMC simulations and the mean field theory based on resonating trimers suggests the AF phase and in-plane FM phase can be interpreted as a Mott insulator and superfluid of trimer states respectively. While the thermal transitions of the in-plane FM phase are well described by the Kosterlitz-Thouless transition, the quantum phase transition from the AF phase to in-plane FM phase undergo a direct second order insulator-superfluid transition upon increasing magnetic field.Comment: 7 pages, 8 figures. Revised version, accepted by PRB