20 research outputs found
Applications of Jarzynski's relation in lattice gauge theories
Jarzynski's equality is a well-known result in statistical mechanics,
relating free-energy differences between equilibrium ensembles with
fluctuations in the work performed during non-equilibrium transformations from
one ensemble to the other. In this work, an extension of this relation to
lattice gauge theory will be presented, along with numerical results for the
gauge model in three dimensions and for the equation of state in
Yang-Mills theory in four dimensions. Then, further
applications will be discussed, in particular for the Schr\"odinger functional
and for the study of QCD in strong magnetic fields.Comment: 7 pages, 2 figures, presented at the 34th International Symposium on
Lattice Field Theory (Lattice 2016), 24-30 July 2016, Southampton, U
Jarzynski’s theorem for lattice gauge theory
Jarzynski's theorem is a well-known equality in statistical mechanics, which
relates fluctuations in the work performed during a non-equilibrium
transformation of a system, to the free-energy difference between two
equilibrium ensembles. In this article, we apply Jarzynski's theorem in lattice
gauge theory, for two examples of challenging computational problems, namely
the calculation of interface free energies and the determination of the
equation of state. We conclude with a discussion of further applications of
interest in QCD and in other strongly coupled gauge theories, in particular for
the Schroedinger functional and for simulations at finite density using
reweighting techniques.Comment: 1+29 pages, 2 pdf figures1+29 pages, 2 pdf figures; v2: 1+34 pages, 2
pdf figures: presentation of the theorem proof in section 2 improved with
additional details, discussion in sections 3 and 4 expanded, misprints
corrected; matches the journal versio
Critical dynamics in trapped particle systems
We discuss the effects of a trapping space-dependent potential on the
critical dynamics of lattice gas models. Scaling arguments provide a dynamic
trap-size scaling framework to describe how critical dynamics develops in the
large trap-size limit. We present numerical results for the relaxational
dynamics of a two-dimensional lattice gas (Ising) model in the presence of a
harmonic trap, which support the dynamic trap-size scaling scenario.Comment: 7 page
Experimental and Numerical Study of the Effect of Surface Patterning on the Frictional Properties of Polymer Surfaces
We describe benchmark experiments to evaluate the frictional properties of
laser patterned low-density polyethylene as a function of sliding velocity,
normal force and humidity. The pattern is a square lattice of square cavities
with sub-mm spacing. We find that dynamic friction decreases compared to
non-patterned surfaces, since stress concentrations lead to anticipated
detachment, and that stick-slip behavior is also affected. Friction increases
with humidity, and the onset of stick-slip events occurs in the high humidity
regime. Experimental results are compared with numerical simulations of a
simplified 2-D spring-block model. A good qualitative agreement can be obtained
by introducing a deviation from the linear behavior of the Amontons-Coulomb law
with the load, due to a saturation in the effective contact area with pressure.
This also leads also to the improvement of the quantitative results of the
spring-block model by reducing the discrepancy with the experimental results,
indicating the robustness of the adopted simplified approach, which could be
adopted to design patterned surfaces with controlled friction properties
Tuning friction with composite hierarchical surfaces
N.M.P. is supported by the European Research Council PoC 2015 “Silkene” No. 693670, by the European Commission H2020 under the Graphene Flagship Core 1 No. 696656 (WP14 “Polymer Nanocomposites”) and FET Proactive “Neurofibres” grant No. 732344. G.C. and F.B. are supported by H2020 FET Proactive “Neurofibres” grant No. 732344
Static and dynamic friction of hierarchical surfaces
N.M.P. was supported by the European Research Council
(ERC StG Ideas BIHSNAM Grant No. 279985 and ERC
PoC SILKENE Grant No. 693670) and by the European
Commission under the Graphene Flagship (WP14 “Polymer
nanocomposites”, Grant No. 696656). G.C. and F.B. were
supported by BIHSNAM