arXiv subjects

B. Allés

Publications and source records attributed to B. Allés.

9 recordsLinked to original sources

arXiv2026

The Fredenhagen-Marcu operator in the gauge-Higgs Z(2) LGT at finite temperature

We explore the possibility to use the Fredenhagen-Marcu operator as a candidate order parameter of the deconfinement phase transition in gauge matter systems at finite temperature. Concretely, we compute by numerical simulations this operator in the (2+1)-dimensional Z(2) lattice gauge theory (LGT) with Z(2) gauge fields coupled to Z(2)-valued Higgs fields. While we cannot provide an unambiguous evidence, we present some hints that the Fredenhagen-Marcu operator is capable of distinguishing the deconfinement phase from the Higgs and confinement phases of the theory.

hep-lat↗

arXiv2025

Confinement-Higgs and deconfinement-Higgs transitions in four-dimensional SU(2) LGT at finite temperature

We re-examine by numerical simulation the phase structure of the (3+1)-dimensional SU(2) lattice gauge theory (LGT) with gauge fields coupled to Higgs fields at finite temperature. Concretely, we explore two different order parameters which are able to distinguish the three phases of the theory: (i) the Fredenhagen-Marcu operator used to discriminate between deconfinement and confinement/Higgs phases and (ii) the Greensite-Matsuyama overlap operator proposed recently to distinguish confinement and Higgs phases.

hep-lat↗

arXiv2025

Confinement-Higgs and deconfinement-Higgs transitions in three-dimensional $Z(2)$ LGT

We re-examine by numerical simulation the phase structure of the three-dimensional Abelian lattice gauge theory (LGT) with $Z(2)$ gauge fields coupled to $Z(2)$-valued Higgs fields. Concretely, we explore two different order parameters which are able to distinguish the three phases of the theory: (i) the Fredenhagen-Marcu operator used to discriminate between deconfinement and confinement/Higgs phases and (ii) the Greensite-Matsuyama overlap operator proposed recently to distinguish confinement and Higgs phases. The latter operator is an analog of the overlap Edwards-Anderson order parameter for spin-glasses. According to it, the Higgs phase is realized as a glassy phase of the gauge system. For this reason standard tricks for simulations of spin-glass phases are utilized in this work, namely tempered Monte Carlo and averaging over replicas. In addition, we also present results for a certain definition of distance between Higgs field configurations. Finally, we calculate various gauge-invariant correlation functions in order to extract the corresponding masses.

hep-lat↗

arXiv2023

Lattice gauge theories in the strong coupling and static limits as a sign-problem-free Ising model

The effective action of the SU(N) Polyakov loop model in the strong coupling region and in the static limit for the quark determinant can be mapped onto the Ising model in any dimensions, with the Ising variables attached on the links of the lattice. We use this reformulation to study the finite temperature SU(2) lattice gauge theory at finite baryon density.

hep-lat↗

arXiv2013

A new approach to the two-dimensional $σ$-model with a topological charge

Based on character decomposition, a dual transformation is introduced leading to two formulations of the theory which should allow for a removal/softening of the sign problem in the original version. Very preliminar numerical results are commented and remaining problems discussed.

hep-lat↗

arXiv2010

Monte Carlo study of the two-dimensional site-diluted dipolar Ising model

By tempered Monte Carlo simulations, we study 2D site-diluted dipolar Ising systems. Dipoles are randomly placed on a fraction x of all L^2 sites in a square lattice, and point along a common crystalline axis. For x_c< x<=1, where x_c = 0.79(5), we find an antiferromagnetic phase below a temperature which vanishes as x approaches x_c from above. At lower values of x, we study (i) distributions of the spin--glass (SG) overlap q, (ii) their relative mean square deviation Delta_q^2 and kurtosis and (iii) xi_L/L, where xi_L is a SG correlation length. From their variation with temperature and system size, we find that the paramagnetic phase covers the entire T>0 range. Our results enable us to obtain an estimate of the critical exponent associated to the correlation length at T=0, 1/nu=0.35(10).

cond-mat.dis-nn↗

arXiv2004

Topological susceptibility at zero and finite $T$ in SU(3) Yang-Mills theory

We determine the topological susceptibility $χ$ at T=0 in pure SU(3) gauge theory and its behaviour at finite $T$ across the deconfining transition. We use an improved topological charge density operator. $χ$ drops sharply by one order of magnitude at the deconfining temperature $T_c$.

hep-lat↗

arXiv1996

Hybrid Monte Carlo and topological modes of full QCD

We investigate the performance of the hybrid Monte Carlo algorithm, the standard algorithm used for lattice QCD simulations involving fermions, in updating non-trivial global topological structures. We find that the hybrid Monte Carlo algorithm has serious problems decorrelating the global topological charge at the values of $β$ and $m$ currently simulated, where continuum physics should be approximately realized. This represents a warning which must be seriously considered when simulating full QCD by hybrid Monte Carlo.

hep-lat↗

arXiv1996

Decorrelating the topology in full QCD

We investigate the performance of the hybrid Monte Carlo algorithm in updating non-trivial global topological structures. We find that the hybrid Monte Carlo algorithm has serious problems decorrelating the global topological charge. This represents a warning which must be seriously considered when simulating full QCD, regardless of the number and type of fermions, with this or any similar algorithm. Simulated tempering is examined as a means of accelerating the decorrelation.

hep-lat↗