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M. Muller-Preussker

Publications and source records attributed to M. Muller-Preussker.

31 records · Page 2Linked to original sources
arXiv2007

Modified SO(3) Lattice Gauge Theory at non zero T with Parallel Tempering: Monopole and Vortex Condensation

The deconfinement transition is studied close to the continuum limit of SO(3) lattice gauge theory. High barriers for tunnelling among different twist sectors causing loss of ergodicity for local update algorithms are circumvented by means of parallel tempering. We compute monopole and center vortex free energies both within the confining phase and through the deconfinement transition. We discuss in detail the general problem of defining order parameters for adjoint actions.

hep-lat↗
arXiv2006

Vortex free energy and deconfinement in center-blind discretizations of Yang-Mills theories

Maximal 't Hooft loops are studied in SO(3) lattice gauge theory at finite temperature T. Tunneling barriers among twist sectors causing loss of ergodicity for local update algorithms are overcome through parallel tempering, enabling us to measure the vortex free energy F and to identify a deconfinement transition at some $β_A^{crit}$. The behavior of F below $β_A^{crit}$ shows however striking differences with what is expected from discretizations in the fundamental representation.

hep-th↗
arXiv2003

Extracting physics from an unphysical situation: light mesons in a small box

Quantum Chromo Dynamics is considered in a setup where the light mesons are squeezed into unphysically small boxes. We show how such a situation can be used to determine the couplings of the low energy chiral Lagrangian from lattice simulations, applying chirally invariant formulations of lattice fermions.

physics.comp-ph↗
arXiv2002

SO(3) Yang-Mills theory on the lattice

We numerically investigate the phase structure of pure SO(3) LGT at zero and non-zero temperature in the presence of a Z2 blind monopole chemical potential. The physical meaning of the different phases, a possible symmetry breaking mechanism as well as the existence of an order parameter for the finite temperature phase transition are discussed.

hep-lat↗
arXiv2002

Parallel tempering in full QCD with Wilson fermions

We study the performance of QCD simulations with dynamical Wilson fermions by combining the Hybrid Monte Carlo algorithm with parallel tempering on $10^4$ and $12^4$ lattices. In order to compare tempered with standard simulations, covariance matrices between sub-ensembles have to be formulated and evaluated using the general properties of autocorrelations of the parallel tempering algorithm. We find that rendering the hopping parameter $κ$ dynamical does not lead to an essential improvement. We point out possible reasons for this observation and discuss more suitable ways of applying parallel tempering to QCD.

hep-lat↗
arXiv2001

Continuum limit in abelian projected SU(2) lattice gauge theory

We study the continuum limit of the abelian string tension and the density of abelian monopoles calculated after carefully fixing the maximal abelian gauge by employing the simulated annealing algorithm. We present the evidence that the abelian string tension converges to the nonabelian one in the continuum limit. For the monopole density we confirm earlier findings that the density of the properly defined infrared monopoles has correct scaling while the total density seems divergent in the continuum limit due to ultraviolate contributions. We also compare with results obtained with the usual iterative gauge fixing algorithm.

hep-lat↗
arXiv2001

Finite temperature phase transition, adjoint Polyakov loop and topology in SU(2) LGT

We investigate the phase structure of pure SU(2) LGT at finite temperature in the mixed fundamental and adjoint representation modified with a Z2 monopole chemical potential. The decoupling of the finite temperature phase transition from unphysical zero temperature bulk phase transitions is analyzed with special emphasis on the continuum limit. The possible relation of the adjoint Polyakov loop to an order parameter for the finite temperature phase transition and to the topological structure of the theory is discussed.

hep-lat↗
arXiv2000

Lorentz gauge fixing and lattice QED

The Gribov ambiguity problem is studied for compact lattice QED within the Lorentz gauge. In the Coulomb phase, Gribov copies are mainly caused by double Dirac sheets and zero-momentum modes of the gauge fields. Removing them by (non-) periodic gauge transformations allows to reach the absolute extremum of the Lorentz gauge functional. For standard Lorentz gauge fixing the Wilson fermion correlator turns out to be strongly effected by the zero-momentum modes. A reliable fermion mass estimate requires the proper treatment of these modes.

hep-lat↗
arXiv2000

Half-integer topological charges below and above the deconfinement transition?

For pure SU(2) lattice gauge theory at finite T, by the help of the cooling method, we search for classical (approximate) solutions having non-trivial holonomy at the spatial boundary. We identify various typical objects and provide their relative frequency of occurence for the confinement and deconfinement phases. Among the configurations obtained we see also the dissociated BPS monopole pairs recently discussed by van Baal and collaborators.

hep-lat↗
arXiv2000

Field strength correlators in the instanton gas: The importance of the two-instanton contribution

The field strength correlators at zero temperature are semi-classically evaluated fitting the random instanton liquid model to lattice data for quenched SU(3) lattice gauge theory. We restrict ourselves to the lowest order in an instanton density expansion necessary to explain the difference between transverse and longitudinal correlation functions. In the instanton-instanton and instanton-antiinstanton contributions the Schwinger line factors neglected in a previous analysis are numerically taken into account in a weighted Monte Carlo evaluation. This leads to different estimates for instanton size and density. A reasonable description of the correlators within the intermediate range from 0.4 fm to 1 fm is obtained.

hep-ph↗