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Orlando Oliveira10/09/2019, 09:10
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Pieter Maris10/09/2019, 09:20
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Fabio Siringo10/09/2019, 09:50
A purely analytical approach to non-perturbative QCD is discussed.
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The exact, gauge-fixed, Faddeev-Popov Lagrangian of Yang-Mills theory is studied by the screened massive expansion which emerges from a mere change of the expansion point of ordinary perturbation theory. The gluon propagator has gauge-invariant complex conjugated poles which might give a direct dynamical proof of gluon... -
Peter Lowdon10/09/2019, 11:00
Local formulations of QFT imply that gauge theory correlators can potentially contain generalised infrared poles. In this talk I will outline the theoretical significance of these components, and report on recent lattice fit results for the gluon propagator.
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Wayne Polyzou (University of Iowa)10/09/2019, 13:30
The inability to distinguish inertial coordinate systems by measuring
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quantum observables implies that equivalent states in different
inertial coordinate systems are related by a unitary representation of
the Poincar\'e group on the Hilbert space of the quantum theory.
These representations can be decomposed into a direct integral of
irreducible representations. This decomposition is... -
Prof. Gastao Krein (Instituto de Fisica Teorica, UNESP)10/09/2019, 14:20
I discuss results of a recent study on the analytic structure of the quark propagator in Minkowski space. The analytic structure of the quark propagator in Minkowski space is more complex than in Euclidean space due to the possible existence of poles and branch cuts at timelike momenta. Here I discuss a computational method based on the spectral representation of the propagator. The method...
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Prof. José Emílio Ribeiro10/09/2019, 15:30
Given any effective Hamiltonian possessing the mechanism of spontaneous chiral symmetry it can be mapped to an equivalent problem of several interacting spins, by means of a Bravyi-Kitaev transformation. Jordan-Wigner transformations are also discussed.
The resulting Hamiltonian is on a suitable form to be implemented on a digital quantum computer, where spins are mapped into qubits. We...
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Vladimir Sauli11/09/2019, 09:00
The definition and the way to extract Nakanishi representation for propagators and triple vertices in Gauge Theories will be presented during the talk. How they can be usefull for calculation of meson electromagnetic form factors in Minkowski space will be ilustrated in cases of the VHP and the pion TFF.
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Nicolas Wink11/09/2019, 09:50
We review some general aspects of calculations in Minkowski space-time with Functional Methods with a focus on the Functional Renormalization Group.
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In particular the implications of having an momentum dependent regulator present are discussed and results for a scalar theory are presented.
Insights from calculations are used to construct improved methods for spectral reconstructions,... -
Jon-Ivar Skullerud (National University of Ireland Maynooth)11/09/2019, 11:00
I will present an overview of results for gluon, ghost and quark propagators and veretices from lattice QCD, and discuss what this may tell us about their analytic structure.
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Attilio Cucchieri, Tereza Mendes11/09/2019, 13:30
We study the continuum limit of SU(2) Landau-gauge gluon and ghost propagators, obtained from numerical simulations performed on lattice volumes of up to $192^4$, in the scaling region.
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David Dudal11/09/2019, 14:20
We discuss how to extract from lattice data information about the (unphysical as gauge variant) spectral representation of gluons and ghosts using a regularized inversion strategy, compatible with the standard Källen-Lehmann spectral integral, whilst allowing generalizations thereof, namely with non-positive density and/or complex conjugate poles.
We also discuss how to introduce gauge...
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Alexandre Salas-Bernárdez11/09/2019, 16:30Posters
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Pablo Pais11/09/2019, 16:40Posters
A new topological invariant quantity, sensitive to the analytic structure of both fermionic and bosonic propagators, is proposed. A generalization compatible with the presence of complex poles is introduced and applied to the classification of propagators typically emerging from non-perturbative considerations. We present partial evidence that this topological number can be used to detect...
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Paulo Silva (Center for Physics, University of Coimbra)11/09/2019, 16:40Posters
We report on the computation of the quark propagator at finite temperature in the Landau gauge using quenched gauge configurations. The propagator form factors are computed for various temperatures, above and below the gluon deconfinement temperature $T_c$, and for all the Matsubara frequencies. Significant differences are found between the form factores below and above $T_c$, which suggest a...
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24. Nontrivial analytic structure of fermion propagators: Truncation Artefact or Confinement Signal?Pieter Maris (Iowa State University)11/09/2019, 16:40Posters
Dyson-Schwinger studies of the fermion propagator are typically performed in Euclidean metric, providing information on the nonperturbative behavior of the fermion propagator at spacelike momenta. It has been known for more than 40 years that an analytic continuation to the entire complex momentum plane can, and often does, reveal 'mass-like' singularities at complex-conjugate momenta, even...
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Dr João Pacheco de Melo ([1]~Laboratório de Física Teórica e Computacional - LFTC - Universidade Cruzeiro do Sul/Universidade Cidade de São Paulo,SP., Brazil)11/09/2019, 16:40Posters
The pion structure in Minkowski space is described in terms of an analytic model of the Bethe–Salpeter amplitude combined with Euclidean Lattice QCD results.
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The model is physically motivated to take into account the running quark mass, which is fitted to Lattice QCD data. In the present work, we extend the an previus work, with the present model utilized to calculated the pion... -
Wayne de Paula (Instituto Tecnologico de Aeronautica)11/09/2019, 16:40Posters
An important tool to deal with the formulation in Minkowski space is the Integral
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Representation (IR) proposed by Nakanishi.
In this work, we use the IR to obtain a solution of the Dyson-Schwinger equation directly in Minkowski space, and compare with a solution in a rotated axis from the Euclidean axis, what we call ``Un-Wick rotation''. To this end we must find the relation between the... -
Dr Markus Huber (Giessen University), Richard Williams (University of Giessen)11/09/2019, 16:50Posters
We show results for propagators and vertices in Yang-Mills theory and QCD obtained from the 3PI effective action. Their use in calculating bound-states and resonances requires access to complex momenta, necessitating special care. We perform appropriate deformations of the integration contour to avoid cuts and poles and present corresponding results for bound states as well as first results...
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11/09/2019, 19:30
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Teresa Peña12/09/2019, 09:00
Wait to be defined by the speaker.
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Giovanni Salme' (INFN - National Institute for Nuclear Physics)12/09/2019, 09:50
A survey of the challenges in solving the ladder Bethe-Salpeter equation with spin dof, within an approach able to be played directly in Minokowski space, is presented. The interesting features of the light-front distributions for both two-fermion and fermion-scalar bound systems are discussed in view of possible correlations with the underlying dynamical interaction.
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Prof. José Rodriguez Quintero (Universidad de Huelva)12/09/2019, 11:00
We shall report on the model building of the pion GPD, within the DGLAP kinematic region, through the overlap of light-front wave functions. The wave functions can be modelled on the basis of the so-called Nakanishi representation and brought to make contact with realistic solutions of the Bethe-Salpeter equation. Then, we will capitalise on a new type of process-independent QCD charge to...
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Dr Alexander Rothkopf (University of Stavanger)12/09/2019, 13:30
The extraction of spectral functions from Euclidean correlator data, simulated non-perturbatively at finite temperature, using first principles lattice QCD is a central challenge of modern high energy nuclear physics. In this talk I will first discuss different theoretical approaches, currently deployed to attack this problem, before showcasing recent progress and outstanding challenges in the...
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Gernot Eichmann (University of Lisbon)12/09/2019, 14:20
We calculate the onshell 2 → 2 scattering amplitude in a scalar model to exemplify the use of contour deformations when solving Lorentz-invariant integral equations. The integrals produce branch cuts in the complex plane of the integrand which prohibit a naive Euclidean integration path. By employing contour deformations, we can also access the kinematical regions associated with the...
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Ian C. Cloet12/09/2019, 15:30
The pion and kaon occupy a special place in QCD as they are bound-states of a dressed-quark and a dressed-antiquark, but would also be massless in the chiral-limit because of dynamical chiral symmetry breaking (DCSB) in QCD. The structure of these Nambu-Goldstone bosons is therefore intimately tied to key questions in QCD, such as, the origin of hadron masses and color confinement. This talk...
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Meijian Li (Iowa State University)Posters
Heavy quarkonium has been solved as a relativistic bound state using Basis Light-Front Quantization (BLFQ), a non-perturbative Hamiltonian approach. We aim to extend the formalism from the valence Fock sector $|q \bar{q}>$ to higher Fock space by including the $|q \bar{q} q \bar{q}>$ sector, in hopes of bringing new aspects into the QCD bound states.
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Pieter Maris (Iowa State University)
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Pieter Maris
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Pieter Maris
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Orlando Oliveira
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