282 research outputs found
Hybrid Monte-Carlo simulation of interacting tight-binding model of graphene
In this work, results are presented of Hybrid-Monte-Carlo simulations of the
tight-binding Hamiltonian of graphene, coupled to an instantaneous long-range
two-body potential which is modeled by a Hubbard-Stratonovich auxiliary field.
We present an investigation of the spontaneous breaking of the sublattice
symmetry, which corresponds to a phase transition from a conducting to an
insulating phase and which occurs when the effective fine-structure constant
of the system crosses above a certain threshold .
Qualitative comparisons to earlier works on the subject (which used larger
system sizes and higher statistics) are made and it is established that
is of a plausible magnitude in our simulations. Also, we discuss
differences between simulations using compact and non-compact variants of the
Hubbard field and present a quantitative comparison of distinct discretization
schemes of the Euclidean time-like dimension in the Fermion operator.Comment: 7 pages, 1 figure, presented at the 31st International Symposium on
Lattice Field Theory (Lattice 2013), 29 July - 3 August 2013, Mainz, German
Spectrum of QCD at Finite Isospin Density
We study the phase diagram of QCD at finite isospin density using two flavors
of staggered quarks. We investigate the low temperature region of the phase
diagram where we find a pion condensation phase at high chemical potential. We
started a basic analysis of the spectrum at finite isospin density. In
particular, we measured pion, rho and nucleon masses inside and outside of the
pion condensation phase. In agreement with previous studies in two-color QCD at
finite baryon density we find that the Polyakov loop does not depend on the
density in the staggered formulation.Comment: 8 pages, 7 figures, proceedings of Lattice2017, Granada, Spai
Effective potential for SU(2) Polyakov loops and Wilson loop eigenvalues
We simulate SU(2) gauge theory at temperatures ranging from slightly below
to roughly for two different values of the gauge coupling. Using a
histogram method, we extract the effective potential for the Polyakov loop and
for the phases of the eigenvalues of the thermal Wilson loop, in both the
fundamental and adjoint representations. We show that the classical potential
of the fundamental loop can be parametrized within a simple model which
includes a Vandermonde potential and terms linear and quadratic in the Polyakov
loop. We discuss how parametrizations for the other cases can be obtained from
this model.Comment: 16 pages, 39 figure
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