188 citations · 519 across the 8 of their papers we have counts for
10 papers
Four-quark states from functional methods
Joshua Hoffer, Christian S. Fischer
The discovery of four-quark states attracted a lot of attention from the theoretical as well as the experimental side. To study their properties from QCD we use a functional framew…
Four-quark states from functional methods
Gernot Eichmann, Christian S. Fischer, Walter Heupel +2
In this feature article we summarise and highlight aspects of the treatment of four-quark states with functional methods. Model approaches to those exotic mesons almost inevitably…
Light mesons in QCD and unquenching effects from the 3PI effective action
Richard Williams, Christian S. Fischer, Walter Heupel
We investigate the impact of unquenching effects on QCD Green's functions, in the form of quark-loop contributions to both the gluon propagator and three-gluon vertex, in a three-l…
The light scalar mesons as tetraquarks
Gernot Eichmann, Christian S. Fischer, Walter Heupel
We present a numerical solution of the four-quark Bethe-Salpeter equation for ground-state scalar tetraquarks with J^PC = 0^++. We find that the four-body equation dynamically gene…
Tetraquarks from the Bethe-Salpeter equation
Gernot Eichmann, Christian S. Fischer, Walter Heupel
We present a numerical solution of the four-quark Bethe-Salpeter equation for a scalar tetraquark. We find that the four-body equation dynamically generates pseudoscalar poles in t…
Four-point functions and the permutation group S4
Gernot Eichmann, Christian S. Fischer, Walter Heupel
Four-point functions are at the heart of many interesting physical processes. A prime example is the light-by-light scattering amplitude, which plays an important role in the calcu…
The muon g-2: Dyson-Schwinger status on hadronic light-by-light scattering
Gernot Eichmann, Christian S. Fischer, Walter Heupel +1
We give a status report on the hadronic light-by-light scattering contribution to the muon's anomalous magnetic moment from the Dyson-Schwinger approach. We discuss novel, model-in…
Beyond Rainbow-Ladder in bound state equations
Walter Heupel, Tobias Goecke, Christian S. Fischer
In this work we devise a new method to study quark anti-quark interactions beyond simple ladder-exchange that yield massless pions in the chiral limit. The method is based on the r…
The role of pions as virtual constituents of light bound states
Walter Heupel, Stanislav Kubrak, Gernot Eichmann +1
We summarize recent results for the spectrum and properties of light pseudoscalar and scalar hadrons in a functional approach to QCD using Dyson-Schwinger and Bethe-Salpeter equati…
Tetraquark bound states in a Bethe-Salpeter approach
Walter Heupel, Gernot Eichmann, Christian S. Fischer
We determine the mass of tetraquark bound states from a coupled system of covariant Bethe-Salpeter equations. Similar in spirit to the quark-diquark model of the nucleon, we approx…