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A. Laser

Publications and source records attributed to A. Laser.

7 recordsLinked to original sources
arXiv1998

Nonperturbative Contributions to the Hot Electroweak Potential and the Crossover

We discuss nonperturbative contributions to the 3-dimensional one-loop effective potential of the electroweak theory at high temperatures in the framework of the stochastic vacuum model. It assumes a gauge-field background with Gaussian correlations which leads to confinement. The instability of =0 in Yang-Mills theory appears for small Higgs expectation value <ϕ^2> in an IR regularized form. The gauge boson propagator obtains a positive momentum-dependent ``diamagnetic'' effective (mass)^2 due to confinement effects and a negative one due to ``paramagnetic'' spin-spin interactions which are related to the =0 instability. Numerical evaluation of an approximate effective potential containing these masses shows qualitatively the fading away of the first-order phase transition with increasing Higgs mass which was observed in lattice calculations. The crossover point can be roughly determined postulating that the effective ϕ^4 and ϕ^2 terms vanish there.

hep-ph↗
arXiv1996

Non-perturbative correlation masses in the hot electroweak phase

The effective action describing the long range fluctuations in the high temperature phase of the electroweak standard theory is a strongly coupled SU(2)-Higgs-model in three dimensions. We outline in detail a model in which the spatial correlation scales in this phase are calculated as inverse relativistic bound state masses. Selection rules for these states are derived. The correlation masses are calculated by evaluating the bound state Green's function. The scalar-scalar-potential and its influence on the masses is investigated. The predictions for the correlation masses agree very well with the lattice data available now.

hep-ph↗
arXiv1995

Perturbative Contributions to the Electroweak Interface Tension

The main perturbative contribution to the free energy of an electroweak interface is due to the effective potential and the tree level kinetic term. The derivative corrections are investigated with one-loop perturbation theory. The action is treated in derivative, in heat kernel, and in a multi local expansion. The massive contributions turn out to be well described by the Z-factor. The massless mode, plagued by infrared problems, is numerically less important. Its perturbatively reliable part can by calculated in derivative expansion as well. A self consistent way to include the Z-factor in the formula for the interface tension is presented.

hep-ph↗
arXiv1995

Bound States in the Hot Electroweak Phase

The high temperature phase of the electroweak standard theory is described by a strongly coupled SU(2)-Higgs-model in three dimensions. As in the Abbott-Farhi-model Higgs and W-boson are low lying bound states. Using a method by Simonov based on the Feynman-Schwinger representation of correlators we calculate the masses of these states. Our results are compared with lattice masses.

hep-ph↗
arXiv1994

Critical Bubbles and Fluctuations at the Electroweak Phase Transition

We discuss the critical bubbles of the electroweak phase transition using an effective high-temperature 3-dimensional action for the Higgs field $φ$. The separate integration of gauge and Goldstone boson degrees of freedom is conveniently described in the 't Hooft-Feynman covariant background gauge. The effective dimensionless gauge coupling $g_3(T)^2$ in the broken phase is well behaved throughout the phase transition. However, the behavior of the one-loop $Z(φ)$ factors of the Higgs and gauge kinetic terms signalizes the breakdown of the derivative expansion and of the perturbative expansion for a range of small $φ$ values increasing with the Higgs mass $m_H$. Taking a functional $S_z[φ]$ with constant $Z(φ)=z$ instead of the full non-local effective action in some neighborhood of the saddlepoint we are calculating the critical bubbles for several temperatures. The fluctuation determinant is calculated to high accuracy using a variant of the heat kernel method. It gives a strong suppression of the transition rate compared to previous estimates.

hep-ph↗