Oscar Akerlund

U(1) lattice gauge theory with a topological action

A bstractWe investigate the phase diagram of the compact U(1) lattice gauge theory in four dimensions using a non-standard action which is invariant under continuous de-formations of the plaquette angles. Just as for the Wilson action, we find a weakly first order transition, separating a confining phase where magnetic monopoles condense, and a Coulomb phase where monopoles are dilute. We also find a third phase where monopoles are completely absent. However, since the monopoles do not influence the long-distance prop-erties of the Coulomb phase, the physics is smooth across the singularity in the monopole density. The topological action offers an algorithmic advantage for the computation of the free energy.

Sampling of General Correlators in Worm-Algorithm Based Simulations

Abstract Using the complex ϕ 4 -model as a prototype for a system which is simulated by a worm algorithm, we show that not only the charged correlator 〈 ϕ ⁎ ( x ) ϕ ( y ) 〉 , but also more general correlators such as 〈 | ϕ ( x ) | | ϕ ( y ) | 〉 or 〈 arg ⁡ ( ϕ ( x ) ) arg ⁡ ( ϕ ( y ) ) 〉 , as well as condensates like 〈 | ϕ | 〉 , can be measured at every step of the Monte Carlo evolution of the worm instead of on closed-worm configurations only. The method generalizes straightforwardly to other systems simulated by worms, such as spin or sigma models.

Oscillating propagators in heavy-dense QCD

A bstractUsing Monte Carlo simulations and extended mean field theory calculations we show that the 3-dimensional ℤ3 spin model with complex external fields has non-monotonic spatial correlators in some regions of its parameter space. This model serves as a proxy for heavy-dense QCD in (3 + 1) dimensions. Non-monotonic spatial correlators are intrinsically related to a complex mass spectrum and a liquid-like (or crystalline) behavior. A liquid phase could have implications for heavy-ion experiments, where it could leave detectable signals in the spatial correlations of baryons.

Higgs-Yukawa model with higher dimension operators via extended mean field theory

Using extended mean field theory (EMFT) on the lattice, we study properties of the Higgs-Yukawa model as an approximation of the standard model Higgs sector, and the effect of higher dimension operators. We note that the discussion of vacuum stability is completely modified in the presence of a

Effects of higher dimension operators on the Standard Model Higgs sector

\phi^6

Gauge-invariant signatures of spontaneous gauge symmetry breaking by the Hosotani mechanism

term, and that the Higgs mass no longer appears fine tuned. We also study the finite temperature transition. Without higher dimension operators the transition is found to be second order (crossover with gauge fields) for the experimental value of the Higgs mass

Dynamical mean field approximation applied to quantum field theory

M_h=125

Mean distribution approach to spin and gauge theories

GeV. By taking a

The Higgs-Yukawa model with higher dimension operators via EMFT

\phi^6

Extended Mean Field study of complex

interaction in the Higgs potential as a proxy for a UV completion of the standard model, the transition becomes stronger and turns first order if the scale of new physics, i.e. the mass of the lightest mediator particle, is around