Conveners
Tuesday AM: 1
- Paulo Bedaque (University of Maryland)
Tuesday AM: 2
- Szabolcs Borsanyi (University of Wuppertal)
Prof.
Biagio Lucini
(Swansea University)
02/08/2016, 09:00
Quantum Field Theories of dense, cold matter
Talk
Most of the successes of lattice QCD are strictly connected with advances in numerical methods. In particular, importance sampling Monte Carlo methods have underpinned lattice QCD calculations since the early days of the field. However, it is well known that importance sampling methods fail in cases when one has to sample over configurations whose occurrence is suppressed by the Monte Carlo...
Dr
Philippe de Forcrand
(ETH Zurich & CERN)
02/08/2016, 09:45
Quantum Field Theories of dense, cold matter
Talk
Above the Curie temperature, the Ising model partition function can
vanish under the effect of an imaginary magnetic field, as first
shown by Lee and Yang. This system has a severe sign problem.
We study it numerically, using the density of states method.
In particular, we consider how the computer effort scales with
the system size.
Helvio Vairinhos
(ETH Zurich)
02/08/2016, 10:10
Quantum Field Theories of dense, cold matter
Talk
With the help of auxiliary fields, it is possible to integrate out analytically the link variables in lattice gauge theory with staggered fermions, for arbitrary values of the lattice coupling. In the case of N_f=1 QED, the subsequent Grassmann integration yields a dual representation of the partition function, which traces over an ensemble of monomers, dimers, and electron loops coupled to...
Dr
Yuya Tanizaki
(RIKEN BNL Research Center)
02/08/2016, 11:05
Quantum Field Theories of dense, cold matter
Talk
If the classical action takes complex values, the path integral formulation of quantum field theories suffers from the sign problem, and some artifice becomes necessary in order to study their nonperturbative properties. The idea to complexify field variables is a candidate for such tricks, and there are two methods belonging into this category: Lefschetz-thimble path integral and complex...
Prof.
Paulo Bedaque
(University of Maryland)
02/08/2016, 11:50
Quantum Field Theories of dense, cold matter
Talk
We discuss an approach to solve the sign problem based on deforming the region of integration in the path integral from real fields to a manifold in complex space. It generalizes the"Lefschetz thimble" approach that received much attention lately. We discuss principles through a simple geometrical picture, discuss algorithm features required to make the idea work and present examples in simple...
Dr
Francesco Di Renzo
(University of Parma and INFN)
02/08/2016, 12:15
Quantum Field Theories of dense, cold matter
Talk
In the context of the chiral random matrix model we introduced a way to compute lattice quantum field theories on Lefschetz thimbles by taking into account the contributions to the functional integral which come from complete flow lines. The latter are the steepest ascent paths attached to critical points, i.e. the basic building blocks of thimbles. While the thimble regularization was...
