Seminars

• Wolfgang Bietenholz (UNAM, Mexico):
  Topological Lattice Actions
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  A variety of lattice discretizations of continuum actions
  has been considered in the literature, usually requiring the correct classical continuum limit. Here we discuss “weird” lattice formulation without that property, namely lattice actions that are invariant under small deformations of the field configuration. It turns out that universality is powerful enough to still provide the correct quantum continuum limit, despite the absence of any classical limit, or a perturbative expansion. We demonstrate this for a set of non-linear sigma-models. Amazingly, such “weird” lattice actions even have practical benefits, in particular an excellent scaling behavior.
  
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• Kazuyuki Kanaya (University of Tsukuba, Japan):
  Finite density QCD with a histogram method
  show abstract
  After a short review of the motivations and the methods to study finite density QCD, I introduce a histogram method, combined with the reweighting technique, to explore the phase structure of QCD at finite temperatures and densities.
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• Gastão Krein (IFT-UNESP, São Paulo, Brazil):
  Low energy charm in matter: where pieces of insight from the lattice would be most welcome
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• Arthur Maciel (CBPF, Rio de Janeiro, Brazil):
  Searches for the Standard Model Higgs Boson in Hadron Colliders
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  The existence of a Higgs boson is the remaining fundamental ingredient of the Standard Model of particle interactions that has yet to be confirmed. A massive experimental search effort to determine or rule out its existence has spanned four generations of large colliders. The discovery of a scalar boson at CERN, announced in July 4th 2012, has brought a widespread belief that the search has finally met with spectacular success.
  A brief review of the relevance of the Higgs boson in the Standard Model is followed by a survey of the various experimental search strategies, and the tools and methods used. The LHC results from last July are presented, and confronted with the available progress since then. To conclude, a general discussion will consider the main aspects of the future experimental program associated with this new scalar boson, and evaluate the current status of the Standard Model.
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• Jorge Noronha (University of São Paulo, Brazil):
  Quark-Gluon Plasma: The Hottest (and Tiniest) Perfect Fluid Ever Made
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  In this talk I will review the major experimental signatures that have led to the conclusion that a strongly coupled system, called the quark-gluon plasma, has been formed in ultrarelativistic heavy ion collisions. I will also comment on the exciting new connection that has appeared between string theory and nuclear collisions and how the mathematical methods developed in string theory have shed some light on the perfect fluid nature of the quark-gluon plasma.
  
• Elisabetta Pallante (University of Groningen, Netherlands):
  Emergent Conformality in Gauge Theory slides
• André Walker-Loud (Berkeley Lab, USA):
  QCD and Big Bang Nucleosynthesis
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  I will describe efforts to make quantitative connections between our understanding of the nucleosynthesis of light elements during the big bang and QCD, the fundamental theory of strong interactions. The single most important quantity for determining the abundance of helium and other light elements formed in the early universe is the proton-neutron mass splitting. There are two sources of isospin breaking in the Standard Model which contribute, the electromagnetic coupling of the quarks and the down-quark up-quark mass splitting. I will describe our current understanding of both of these contributions to mn – mp and their relation of Big Bang Nucleosynthesis.
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  Tutorial: A Poor Man’s Advanced Fitting Techniques
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  I will describe in a pragmatic way a few techniques that can improve one’s ability to extract information from correlation functions described by a sum of exponentials. These techniques are particularly useful for correlation functions that are not positive-definite (if you did not have the computing resources to compute sink operators which are conjugate to the source operators, and thus utilize the Generalized Eigenvalue Solvers). The techniques I will discuss are know to me as: Variational Projection (VarPro), Input-parameter-free multi-exponential fitting, Generalized Pencil of Function (GPOF) and Matrix Prony.
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• Jacek Wosiek (Jagiellonian University, Poland):
  Two-dimensional gauge theory
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  In the first part of the talk a pedagogical review of the analytic methods in Lattice Field Theory will be given. Topics to be covered are: euclidean partition function, character expansion, gauge fixing, transfer matrix, continuum limit, Feynman kernel, etc. These methods will then be applied to calculate analytically, partition function, and various observables in the two-dimensional pure gauge theory. Effect of boundary conditions, and emergence of the topological charge, will be also illustrated by explicit calculations. Exact Coulomb gauge will be constructed on the lattice and the effective, one degree of freedom, Manton’s hamiltonian rederived from the lattice approach. Generalization for the system with external charges will be also given. In particular, Manton’s  parameter will be explicitly calculated in this case. Finally, if time permits, some less orthodox issues, like description of non-integer, external charges will be introduced.
  
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• James Zanotti (University of Adelaide, Australia)):
  Hadron Structure from Lattice QCD
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  Lattice QCD has the ability to probe the internal structure of hadrons through the computation of lattice three-point functions. The quantities that are receiving the most recent attention are the nucleon electromagnetic form factors, axial charge and quark momentum fraction. I will introduce these concepts as examples of how lattice simulations can probe the structure of hadrons and review some of the technical difficulties that such calculations have to deal with.
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