Diagrammatic approach to soft non-Abelian dynamics at high temperature

The dynamics of soft ($|\vec{p}|\sim g^2 T$) non-Abelian gauge fields at finite temperature is non-perturbative. The effective theory for the soft scale is determined by diagrams with external momenta p_0\lsim g^2 T, $|\vec{p}|\sim g^2 T$ and loop momenta larger than $g^2 T$. We consider the polarization tensor beyond the hard thermal loop approximation, which accounts for loop momenta of order $T$. There are higher loop diagrams, involving also the scale $gT$, which are as important as the hard thermal loops. These higher loop contributions are characteristic for non-Abelian gauge theories and their calculation is simplified by using the hard thermal loop effective theory. Remarkably, the effective one-loop polarization tensor is found to be gauge fixing independent and transverse at leading order in $g$. The transversality indicates that this approach leads to a gauge invariant effective theory.Comment: 23 pages, latex, 4 figures, uses axodraw.sty; discussion of higher loop contributions and of their relation to the Boltzmann equation (Sect. 5) added, several references added, to appear in Nucl. Phys.

Finite baryon density effects on gauge field dynamics

We discuss the effective action for QCD gauge fields at finite temperatures and densities, obtained after integrating out the hardest momentum scales from the system. We show that a non-vanishing baryon density induces a charge conjugation (C) odd operator to the gauge field action, proportional to the chemical potential. Even though it is parametrically smaller than the leading C even operator, it could have an important effect on C odd observables. The same operator appears to be produced by classical kinetic theory, allowing in principle for a non-perturbative study of such processes.Comment: 20 page

Effective Theories for Hot Non-Abelian Dynamics

The dynamics of soft ($|\vec{p}|\sim g^2 T$) non-Abelian gauge fields at finite temperature is non-perturbative. The effective theory for the soft fields can be obtained by first integrating out the momentum scale T, which yields the well known hard thermal loop effective theory. Then the latter is used to integrate out the scale gT. One obtains a Boltzmann equation, which can be solved in a leading logarithmic approximation. The resulting effective theory for the soft fields is described by a Langevin equation, and it is well suited for non-perturbative lattice simulations.Comment: 11 pages, 3 figures; plenary talk given at Conference on Strong and Electroweak Matter (SEWM 98), Copenhagen, Denmark, 2-5 Dec 199

Plasmon properties in classical lattice gauge theory

In order to investigate the features of the classical approximation at high temperatures for real time correlation functions, the plasmon frequencies and damping rates were recently computed numerically in the SU(2)+Higgs model and in the pure SU(2) theory. We compare the lattice results with leading order hard thermal loop resummed perturbation theory. In the broken phase of the SU(2)+Higgs model, we show that the lattice results can be reproduced and that the lattices used are too coarse to observe some important plasmon effects. In the symmetric phase, the main qualitative features of the lattice results can also be understood. In the pure SU(2) theory, on the other hand, there are discrepancies which might point to larger Landau and plasmon damping effects than indicated by perturbation theory.Comment: 17 pages, 5 figures. A few points written more clearly (e.g., in the abstract). A note added concerning two recent papers. Conclusions unchanged. To appear in Phys.Lett.

Equilibration of right-handed electrons

We study the equilibration of right-handed electrons in the symmetric phase of the Standard Model. Due to the smallness of the electron Yukawa coupling, it happens relatively late in the history of the Universe. We compute the equilibration rate at leading order in the Standard Model couplings, by including gauge interactions, the top Yukawa- and the Higgs self-interaction. The dominant contribution is due to $2 \to 2$ particle scattering, even though the rate of (inverse) Higgs decays is strongly enhanced by multiple soft scattering which is included by Landau-Pomeranchuk-Migdal (LPM) resummation. Our numerical result is substantially larger than approximations presented in previous literature.Comment: 31 pages, 5 figures. v2: Added appendix estimating the conversion of right-handed electron number into hypermagnetic fields through the chiral anomaly. References added, minor errors corrected, results and conclusions unchanged, published versio

Changes in the polar vortex: Effects on Antarctic total ozone observations at various stations

October mean total column ozone data from four Antarctic stations form the basis for understanding the evolution of the ozone hole since 1960. While these stations show similar emergence of the ozone hole from 1960 to 1980, the records are divergent in the last two decades. The effects of long-term changes in vortex shape and location are considered by gridding the measurements by equivalent latitude. A clear eastward shift of the mean position of the vortex in October with time is revealed, which changes the fraction of ozone measurements taken inside/outside the vortex for stations in the vortex collar region. After including only those measurements made inside the vortex, ozone behavior in the last two decades at the four stations is very similar. This suggests that dynamical influence must be considered when interpreting and intercomparing ozone measurements from Antarctic stations for detecting ozone recovery and ozone-related changes in Antarctic climate

MSSM Electroweak Baryogenesis and Flavour Mixing in Transport Equations

We make use of the formalism developed in Ref. [1], and calculate the chargino mediated baryogenesis in the Minimal Supersymmetric Standard Model. The formalism makes use of a gradient expansion of the Kadanoff-Baym equations for mixing fermions. For illustrative purposes, we first discuss the semiclassical transport equations for mixing bosons in a space-time dependent Higgs background. To calculate the baryon asymmetry, we solve a standard set of diffusion equations, according to which the chargino asymmetry is transported to the top sector, where it biases sphaleron transitions. At the end we make a qualitative and quantitative comparison of our results with the existing work. We find that the production of the baryon asymmetry of the Universe by CP-violating currents in the chargino sector is strongly constrained by measurements of electric dipole moments.Comment: 30 pages, 6 figures; minor changes, published versio

Trends and variability in stratospheric mixing: 1979–2005

Changes in climate are likely to drive changes in stratospheric mixing with associated implications for changes in transport of ozone from tropical source regions to higher latitudes, transport of water vapour and source gas degradation products from the tropical tropopause layer into the mid-latitude lower stratosphere, and changes in the meridional distribution of long-lived trace gases. To diagnose long-term changes in stratospheric mixing, global monthly fields of Lyapunov exponents were calculated on the 450 K, 550 K, and 650 K isentropic surfaces by applying a trajectory model to wind fields from NCEP/NCAR reanalyses over the period 1979 to 2005. Potential underlying geophysical drivers of trends and variability in these mixing fields were investigated by applying a least squares regression model, which included basis functions for a mean annual cycle, seasonally dependent linear trends, the quasi-biennial oscillation (QBO), the solar cycle, and the El Niño Southern Oscillation (ENSO), to zonal mean time series of the Lyapunov exponents. <br><br> Long-term positive trends in mixing are apparent over southern middle to high latitudes at 450 K through most of the year, while negative trends over southern high latitudes are apparent at 650 K from May to August. Wintertime negative trends in mixing over northern mid-latitudes are apparent at 550 K and 650 K. Over low latitudes, within 40° of the equator, the QBO exerts a strong influence on mixing at all three analysis levels. This QBO influence is strongly modulated by the annual cycle and shows a phase shift across the subtropical mixing barrier. Solar cycle and ENSO influences on mixing are generally not significant. The diagnosed long-term changes in mixing should aid the interpretation of trends in stratospheric trace gases

Design of a Low Cost Short Takeoff-vertical Landing Export Fighter/attack Aircraft

The design of a supersonic short takeoff and vertical landing (STOVL) aircraft is presented that is suitable for export. An advanced four poster, low bypass turbofan engine is to be used for propulsion. Preliminary aerodynamic analysis is presented covering a determination of CD versus CL, CD versus Mach number, as well as best cruise Mach number and altitude. Component locations are presented and center of gravity determined. Cost minimization is achieved through the use of developed subsystems and standard fabrication techniques using nonexotic materials. Conclusions regarding the viability of the STOVL design are presented

Dark Matter Abundance and Electroweak Baryogenesis in the CMSSM

The Minimal Supersymmetric Standard Model has a candidate dark matter particle in its spectrum and may be able to generate the baryon asymmetry of the Universe (BAU) at the electroweak phase transition. In the Constrained MSSM, we find the area of parameter space which is allowed by accelerator and precision tests, which produces a relic dark matter abundance in the observationally favored window 0.1<Omega h^2<0.3, and where baryon plus lepton number violating processes are out of equilibrium after the electroweak phase transition.Comment: 14 pages in LaTeX, including 7 encapsulated postscript figure