The Ising model universality of the electroweak theory

Lattice simulations have shown that the first order electroweak phase transition turns into a regular cross-over at a critical Higgs mass m_{H,c}. We have developed a method which enables us to make a detailed investigation of the critical properties of the electroweak theory at m_{H,c}. We find that the transition falls into the 3d Ising universality class. The continuum limit extrapolation of the critical Higgs mass is m_{H,c} = 72(2) GeV, which implies that there is no electroweak phase transition in the Standard Model.Comment: 3 pages, contribution to LATTICE98(electroweak

Critical behaviour of the Ginzburg-Landau model in the type II region

We study the critical behaviour of the three-dimensional U(1) gauge+Higgs theory (Ginzburg-Landau model) at large scalar self-coupling \lambda (``type II region'') by measuring various correlation lengths as well as the Abrikosov-Nielsen-Olesen vortex tension. We identify different scaling regions as the transition is approached from below, and carry out detailed comparisons with the criticality of the 3d O(2) symmetric scalar theory.Comment: Lattice2001(higgssusy), 3 page

Results from 3D Electroweak Phase Transition Simulations

We study the phase transition in SU(2)-Higgs model on the lattice using the 3D dimensionally reduced formalism. The 3D formalism enables us to obtain highly accurate Monte Carlo results, which we extrapolate both to the infinite volume and to the continuum limit. Our formalism also provides for a well-determined and unique way to relate the results to the perturbation theory. We measure the critical temperature, latent heat and interface tension for Higgs masses up to 70 GeV.Comment: 4 pages uuencoded postscript, contribution to LATTICE 9

Gauge-invariant strings in the 3d U(1)+Higgs theory

We describe how the strings, which are classical solutions of the continuum three-dimensional U(1)+Higgs theory, can be studied on the lattice. The effect of an external magnetic field is also discussed and the first results on the string free energy are presented. It is shown that the string free energy can be used as an order parameter when the scalar self-coupling is large and the transition is continuous.Comment: LATTICE98(higgs); missing author added, no changes to tex

Four-loop logarithms in 3d gauge + Higgs theory

We discuss the logarithmic contributions to the vacuum energy density of the three-dimensional SU(3) + adjoint Higgs theory in its symmetric phase, and relate them to numerical Monte Carlo simulations. We also comment on the implications of these results for perturbative and non-perturbative determinations of the pressure of finite-temperature QCD.Comment: 3 pages, Lattice2002(nonzerot

Baryon-to-entropy ratio in very high energy nuclear collisions

We compute as a function of rapidity $y$ the baryon number carried by quarks and antiquarks with $p_T > p_0 \approx$ 2 GeV produced in Pb+Pb collisions at TeV energies. The computation is carried out in lowest order QCD perturbation theory using structure functions compatible with HERA results. At $p_0=2$ GeV the initial gluon density is both transversally saturated and thermalised in the sense that the energy/gluon equals to that of an ideal gas with the same energy density. Even at these high energies the initial net baryon number density at $y=0$ at $\tau=0.1$ fm will be more than the normal nuclear matter density but the baryon-to-entropy ratio is only $(B-\bar B)/S\sim 1/5000$. Further evolution of the system is discussed and the final baryon-to-entropy ratio is estimated.Comment: 19 pages, including 10 ps-figure

Measuring infrared contributions to the QCD pressure

For the pressure (or free energy) of QCD, four-dimensional (4d) lattice data is available at zero baryon density up to a few times the critical temperature $T_c$. Perturbation theory, on the other hand, has serious convergence problems even at very high temperatures. In a combined analytical and three-dimensional (3d) lattice method, we show that it is possible to compute the QCD pressure from about $2 T_c$ to infinity. The numerical accuracy is good enough to resolve in principle, e.g., logarithmic contributions related to 4-loop perturbation theory.Comment: 3 pages; talk by Y. Schroder at Lattice2001(hightemp