Thermal fluctuations of gauge fields and first order phase transitions in color superconductivity

We study the effects of thermal fluctuations of gluons and the diquark pairing field on the superconducting-to-normal state phase transition in a three-flavor color superconductor, using the Ginzburg-Landau free energy. At high baryon densities, where the system is a type I superconductor, gluonic fluctuations, which dominate over diquark fluctuations, induce a cubic term in the Ginzburg-Landau free energy, as well as large corrections to quadratic and quartic terms of the order parameter. The cubic term leads to a relatively strong first order transition, in contrast with the very weak first order transitions in metallic type I superconductors. The strength of the first order transition decreases with increasing baryon density. In addition gluonic fluctuations lower the critical temperature of the first order transition. We derive explicit formulas for the critical temperature and the discontinuity of the order parameter at the critical point. The validity of the first order transition obtained in the one-loop approximation is also examined by estimating the size of the critical region.Comment: 12 pages, 4 figures, final version published in Phys. Rev.

Preheating of the nonminimally coupled inflaton field

We investigate preheating of an inflaton field $\phi$ coupled nonminimally to a spacetime curvature. In the case of a self-coupling inflaton potential $V(\phi)=\lambda \phi^4/4$, the dynamics of preheating changes by the effect of the negative $\xi$. We find that the nonminimal coupling works in two ways. First, since the initial value of inflaton field for reheating becomes smaller with the increase of $|\xi|$, the evolution of the inflaton quanta is delayed for fixed $\lambda$. Second, the oscillation of the inflaton field is modified and the nonadiabatic change around $\phi=0$ occurs significantly. That makes the resonant band of the fluctuation field wider. Especially for strong coupling regimes $|\xi| \gg 1$, the growth of the inflaton flutuation is dominated by the resonance due to the nonminimal coupling, which leads to the significant enhancement of low momentum modes. Although the final variance of the inflaton fluctuation does notchange significantly compared with the minimally coupled case, we have found that the energy transfer from the homogeneous inflaton to created particles efficiently occurs for $\xi<-60$.Comment: 13pages, 11figure

Resonant particle production with non-minimally coupled scalar fields in preheating after inflation

We investigate a resonant particle production of a scalar field $\chi$ coupled non-minimally to a spacetime curvature $R$ ($\xi R \chi^2$) as well as to an inflaton field $\phi$ ($g^2\phi^2\chi^2$). In the case of $g < 3 \times 10^{-4}$, $\xi$ effect assists $g$-resonance in certain parameter regimes. However, for $g > 3 \times 10^{-4}$, $g$-resonance is not enhanced by $\xi$ effect because of $\xi$ suppression effect as well as a back reaction effect. If $\xi \approx -4$, the maximal fluctuation of produced $\chi$-particle is $\sqrt{}_{max} \approx 2 \times 10^{17}$ GeV for $g < 1 \times 10^{-5}$, which is larger than the minimally coupled case with $g \approx 1 \times 10^{-3}$.Comment: 33pages, 12figures. to appear in Physical Review

Lithium Therapy Improves Neurological Function and Hippocampal Dendritic Arborization in a Spinocerebellar Ataxia Type 1 Mouse Model

Huda Zoghbi and colleagues show that lithium treatment initiated before or after disease onset improves multiple symptoms of neurodegeneration in a mouse model of spinocerebellar ataxia