Exactly solvable model of dissipative vortex tunneling

I consider the problem of vortex tunneling in a two-dimensional superconductor. The vortex dynamics is governed by the Magnus force and the Ohmic friction force. Under-barrier motion in the vicinity of the saddle point of the pinning potential leads to a model with quadratic Hamiltonian which can be analytically diagonalized. I find the dependence of the tunneling probability on the normal state quasiparticle relaxation time $\tau$ with a minimum at $\omega_0\tau\sim 1$, where $\omega_0$ is the level spacing of the quasiparticle bound states inside the vortex core. The results agree qualitatively with the available experimental data.Comment: RevTeX, 6 pages, 2 figures. Published versio

On Exactly Solvable Potentials

We investigate two methods of obtaining exactly solvable potentials with analytic forms.Comment: 13 pages, Latex, to appear in Chineses Journal of Physic

Exceptional hyperbolic 3-manifolds

We correct and complete a conjecture of D. Gabai, R. Meyerhoff and N. Thurston on the classification and properties of thin tubed closed hyperbolic 3-manifolds. We additionally show that if N is a closed hyperbolic 3-manifold, then either N=Vol3 or N contains a closed geodesic that is the core of an embedded tube of radius log(3)/2.Comment: 22 pages, 2 figure

Renormalization Group Study of the Minimal Majoronic Dark Radiation and Dark Matter Model

We study the 1-loop renormalization group equation running in the simplest singlet Majoron model constructed by us earlier to accommodate the dark radiation and dark matter content in the universe. A comprehensive numerical study was performed to explore the whole model parameter space. A smaller effective number of neutrinos $\triangle N_{eff}\sim 0.05$, or a Majoron decoupling temperature higher than the charm quark mass, is preferred. We found that a heavy scalar dark matter, $\rho$, of mass $1.5-4$ TeV is required by the stability of the scalar potential and an operational type-I see-saw mechanism for neutrino masses. A neutral scalar, $S$, of mass in the $10-100$ GeV range and its mixing with the standard model Higgs as large as $0.1$ is also predicted. The dominant decay modes are $S$ into $b\bar{b}$ and/or $\omega\omega$. A sensitive search will come from rare $Z$ decays via the chain $Z\rightarrow S+ f\bar{f}$, where $f$ is a Standard Model fermion, followed by $S$ into a pair of Majoron and/or b-quarks. The interesting consequences of dark matter bound state due to the sizable $S\rho \rho$-coupling are discussed as well. In particular, shower-like events with an apparent neutrino energy at $M_\rho$ could contribute to the observed effective neutrino flux in underground neutrino detectors such as IceCube.Comment: 33 pages,11 figures, published versio

Regulation of autoimmunity and donor cell engraftment by recipient Lyt-2+ cells during the graft-versus-host reaction.

When lymphocytes from DBA/2 mice are transferred to (C57BL X DBA/2)F1 (BDF1) mice, the ensuing graft-vs.-host reaction (GVHR) causes an autoimmune illness resembling human SLE. To examine the role of recipient T cells in this process, BDF1 mice were depleted of L3T4+ or Lyt-2+ cells by thymectomy followed by treatment with mAbs to L3T4 or Lyt-2. This produced sustained depletion of these T cell subsets. Subsequent grafting with parental DBA/2 lymphocytes produced autoimmune disease in mice depleted of L3T4+ cells and controls but not in mice depleted of Lyt-2+ cells. Analysis of blood lymphocytes 4 wk after donor cell transfer demonstrated that BDF1 recipients depleted of Lyt-2+ cells were virtually repopulated with donor T lymphocytes, compared with less than or equal to 35% donor cell engraftment in all other groups. Thus, recipient Lyt-2+ cells influence both host cell engraftment and autoimmunity during the parent-into-F1 GVHR