2,507 research outputs found
Effective lattice Polyakov loop theory vs. full SU(3) Yang-Mills at finite temperature
A three-dimensional effective theory of Polyakov loops has recently been
derived from Wilson's Yang-Mills lattice action by means of a strong coupling
expansion. It is valid in the confined phase up to the deconfinement phase
transition, for which it predicts the correct order and gives quantitative
estimates for the critical coupling. In this work we study its predictive power
for further observables like correlation functions and the equation of state.
We find that the effective theory correctly reproduces qualitative features and
symmetries of the full theory as the continuum is approached. Regarding
quantitative predictions, we identify two classes of observables by numerical
comparison as well as analytic calculations: correlation functions and their
associated mass scales cannot be described accurately from a truncated
effective theory, due to its inherently non-local nature involving long-range
couplings. On the other hand, phase transitions and bulk thermodynamic
quantities are accurately reproduced by the leading local part of the effective
theory. In particular, the effective theory description is numerically superior
when computing the equation of state at low temperatures or the properties of
the phase transition.Comment: 18 pages, 5 figure
Numerical corrections to the strong coupling effective Polyakov-line action for finite T Yang-Mills theory
We consider a three-dimensional effective theory of Polyakov lines derived
previously from lattice Yang-Mills theory and QCD by means of a resummed strong
coupling expansion. The effective theory is useful for investigations of the
phase structure, with a sign problem mild enough to allow simulations also at
finite density. In this work we present a numerical method to determine
improved values for the effective couplings directly from correlators of the 4d
Yang-Mills theory. For values of the gauge coupling up to the vicinity of the
phase transition, the dominant short range effective coupling are well
described by their corresponding strong coupling series. We provide numerical
results also for the longer range interactions, Polyakov lines in higher
representations as well as four-point interactions, and discuss the growing
significance of non-local contributions as the lattice gets finer. Within this
approach the critical Yang-Mills coupling is reproduced to better
than one percent from a one-coupling effective theory on lattices
while up to five couplings are needed on for the same accuracy.Comment: 19 pages, 9 figure
Megasonic Enhanced Electrodeposition
A novel way of filling high aspect ratio vertical interconnection (microvias)
with an aspect ratio of >2:1 is presented. High frequency acoustic streaming at
megasonic frequencies enables the decrease of the Nernst-diffusion layer down
to the sub-micron range, allowing thereby conformal electrodeposition in deep
grooves. Higher throughput and better control over the deposition properties
are possible for the manufacturing of interconnections and metal-based MEMS.Comment: Submitted on behalf of EDA Publishing Association
(http://irevues.inist.fr/handle/2042/16838
Order-disorder transitions in a sheared many body system
Motivated by experiments on sheared suspensions that show a transition
between ordered and disordered phases, we here study the long-time behavior of
a sheared and overdamped 2-d system of particles interacting by repulsive
forces. As a function of interaction strength and shear rate we find
transitions between phases with vanishing and large single-particle diffusion.
In the phases with vanishing single-particle diffusion, the system evolves
towards regular lattices, usually on very slow time scales. Different lattices
can be approached, depending on interaction strength and forcing amplitude. The
disordered state appears in parameter regions where the regular lattices are
unstable. Correlation functions between the particles reveal the formation of
shear bands. In contrast to single particle densities, the spatially resolved
two-particle correlation functions vary with time and allow to determine the
phase within a period. As in the case of the suspensions, motion in the state
with low diffusivity is essentially reversible, whereas in the state with
strong diffusion it is not.Comment: 12 pages, 13 figures; Supplemental Movies:
https://youtu.be/oFcrWo9Vs6E, https://youtu.be/tcowb7o05JQ,
https://youtu.be/GkEUwycn7V4, https://youtu.be/k-XCo8CWFU
Dynamical treatment of Fermi motion in a microscopic description of heavy ion collisions
A quasiclassical Pauli potential is used to simulate the Fermi motion of nucleons in a molecular dynamical simulation of heavy ion collisions. The thermostatic properties of a Fermi gas with and without interactions are presented. The inclusion of this Pauli potential into the quantum molecular dynamics (QMD) approach yields a model with well defined fermionic ground states, which is therefore also able to give the excitation energies of the emitted fragments. The deexcitation mechanisms (particle evaporation and multifragmentation) of the new model are investigated. The dynamics of the QMD with Pauli potential is tested by a wide range of comparisons of calculated and experimental double-differential cross sections for inclusive p-induced reactions at incident energies of 80 to 160 MeV. Results at 256 and 800 MeV incident proton energy are presented as predictions for completed experiments which are as yet unpublished
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