Nicolas Wink
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View article: Physics of the gluon mass gap
Physics of the gluon mass gap Open
It has long been known that the gluon propagator in Landau-gauge QCD exhibits a mass gap; and its emergence has been ascribed to the action of the Schwinger mechanism in the gauge sector of QCD. In the present work, we relate this property…
View article: On the complex structure of Yang-Mills theory
On the complex structure of Yang-Mills theory Open
We consider the coupled set of spectral Dyson-Schwinger equations in Yang-Mills theory for ghost and gluon propagators. Within this set-up, we perform a systematic analytic evaluation of the constraints on generalised spectral representati…
View article: Toward quantitative precision for QCD at large densities
Toward quantitative precision for QCD at large densities Open
QCD at large density reveals a rich phase structure, ranging from a potential critical end point and inhomogeneous phases or moat regimes to color superconducting ones with competing order effects. Resolving this region in the phase diagra…
View article: Lattice QCD estimates of thermal photon production from the QGP
Lattice QCD estimates of thermal photon production from the QGP Open
Thermal photons produced in heavy-ion collision experiments are an important observable for understanding quark-gluon plasma (QGP). The thermal photon rate from the QGP at a given temperature can be calculated from the spectral function of…
View article: Scalar spectral functions from the spectral functional renormalization group
Scalar spectral functions from the spectral functional renormalization group Open
We compute spectral functions in a scalar ϕ4-theory in three spacetime dimensions via the spectral functional renormalization group. This approach allows for the direct, manifestly Lorentz covariant computation of correlation functions in …
View article: Towards quantitative precision in functional QCD I
Towards quantitative precision in functional QCD I Open
Functional approaches are the only first principle QCD setup that allow for direct computations at finite density. Predictive power and quantitative reliability of the respective results can only be obtained within a systematic expansion s…
View article: Bound states from the spectral Bethe-Salpeter equation
Bound states from the spectral Bethe-Salpeter equation Open
We compute the bound state properties of three-dimensional scalar ϕ4 theory in the broken phase. To this end, we extend the recently developed technique of spectral Dyson-Schwinger equations to solve the Bethe-Salpeter equation and determi…
View article: Local discontinuous Galerkin for the functional renormalisation group
Local discontinuous Galerkin for the functional renormalisation group Open
We apply a Local Discontinuous Galerkin discretisation to flow equations of the O(N)-model in the Local Potential Approximation. The improved stability is directly observed by solving the flow equation for various N and space-time dimensio…
View article: Dissipation dynamics of a scalar field
Dissipation dynamics of a scalar field Open
We investigate the dissipation rate of a scalar field in the vicinity of the phase transition and the ordered phase, specifically within the universality class of model A. This dissipation rate holds significant physical relevance, particu…
View article: Yang-Mills glueball masses from spectral reconstruction
Yang-Mills glueball masses from spectral reconstruction Open
We compute masses of the two lightest glueballs from spectral reconstructions of timelike interaction channels of the four-gluon vertex in Landau gauge Yang-Mills theory. The Euclidean spacelike dressings of the vertex are calculated with …
View article: Bound states from the spectral Bethe-Salpeter equation
Bound states from the spectral Bethe-Salpeter equation Open
We compute the bound state properties of three-dimensional scalar $ϕ^4$ theory in the broken phase. To this end, we extend the recently developed technique of spectral Dyson-Schwinger equations to solve the Bethe-Salpeter equation and dete…
View article: Resolving phase transitions with discontinuous Galerkin methods
Resolving phase transitions with discontinuous Galerkin methods Open
We demonstrate the applicability and advantages of Discontinuous Galerkin (DG) schemes in the context of the Functional Renormalization Group (fRG). We investigate the O(N) -model in the large N limit. It is shown that the flow eq…
View article: On the quark spectral function in QCD
On the quark spectral function in QCD Open
We calculate the spectral function of light quark flavours in 2+1 flavour vacuum QCD in the isospin-symmetric approximation. We employ spectral Dyson-Schwinger equations and compute the non-perturbative quark propagator directly in real-ti…
View article: Towards quantitative precision for QCD at large densities
Towards quantitative precision for QCD at large densities Open
QCD at large density reveals a rich phase structure, ranging from a potential critical end point and inhomogeneous phases or moat regimes to color superconducting ones with competing order effects. Resolving this region in the phase diagra…
View article: Dissipation dynamics of a scalar field
Dissipation dynamics of a scalar field Open
We investigate the dissipation rate of a scalar field in the vicinity of the phase transition and the ordered phase, specifically within the universality class of model A. This dissipation rate holds significant physical relevance, particu…
View article: Renormalised spectral flows
Renormalised spectral flows Open
We derive renormalised finite functional flow equations for quantum field theories in real and imaginary time that incorporate scale transformations of the renormalisation conditions, hence implementing a flowing renormalisation. The flows…
View article: The nuclear liquid-gas transition in QCD
The nuclear liquid-gas transition in QCD Open
We estimate the nuclear saturation density and the binding energy in a nuclear liquid from precision data on the coupling of the four-quark scattering vertex in the vector channel, computed within functional QCD. We show that this coupling…
View article: Report on scipost_202307_00019v1
Report on scipost_202307_00019v1 Open
We calculate the spectral function of light quark flavours in 2+1 flavour vacuum QCD in the isospin-symmetric approximation.We employ spectral Dyson-Schwinger equations and compute the non-perturbative quark propagator directly in real-tim…
View article: Report on 1903.09503v4
Report on 1903.09503v4 Open
We demonstrate the applicability and advantages of Discontinuous Galerkin (DG) schemes in the context of the Functional Renormalization Group (fRG).We investigate the O(N )-model in the large N limit.It is shown that the flow equation for …
View article: Numerical RG-time integration of the effective potential: Analysis and benchmark
Numerical RG-time integration of the effective potential: Analysis and benchmark Open
We investigate the renormalization group (RG)-time integration of the effective potential in the functional renormalization group in the presence of spontaneous symmetry breaking and its subsequent convexity restoration on the example of a…
View article: Report on 2210.07597v1
Report on 2210.07597v1 Open
We calculate the spectral function of light quark flavours in 2+1 flavour vacuum QCD in the isospin-symmetric approximation.We employ spectral Dyson-Schwinger equations and compute the non-perturbative quark propagator directly in real-tim…
View article: Nonperturbative strong coupling at timelike momenta
Nonperturbative strong coupling at timelike momenta Open
We compute the strong coupling constant of Landau gauge QCD in the full complex momentum plane, both directly and via spectral reconstruction. In particular, we consider the Taylor coupling given by the product of ghost and gluon dressing …
View article: Scalar spectral functions from the spectral fRG
Scalar spectral functions from the spectral fRG Open
We compute non-perturbative spectral functions in a scalar $ϕ^4$-theory in three spacetime dimensions via the spectral functional renormalisation group. This approach allows for the direct, manifestly Lorentz covariant computation of corre…
View article: Numerical RG-time integration of the effective potential: Analysis and Benchmark
Numerical RG-time integration of the effective potential: Analysis and Benchmark Open
We investigate the RG-time integration of the effective potential in the functional renormalization group in the presence of spontaneous symmetry breaking and its subsequent convexity restoration on the example of a scalar theory in $d=3$.…
View article: Non-perturbative strong coupling at timelike momenta
Non-perturbative strong coupling at timelike momenta Open
We compute the strong coupling constant of Landau gauge QCD in the full complex momentum plane, both directly and via spectral reconstruction. In particular, we consider the Taylor coupling given by the product of ghost and gluon dressing …
View article: Report on 2206.10232v2
Report on 2206.10232v2 Open
We derive renormalised finite functional flow equations for quantum field theories in real and imaginary time that incorporate scale transformations of the renormalisation conditions, hence implementing a flowing renormalisation.The flows …
View article: Yang-Mills glueball masses from spectral reconstruction
Yang-Mills glueball masses from spectral reconstruction Open
We compute masses of the two lightest glueballs from spectral reconstructions of timelike interaction channels of the four-gluon vertex in Landau gauge Yang-Mills theory. The Euclidean spacelike dressings of the vertex are calculated with …
View article: On the quark spectral function in QCD
On the quark spectral function in QCD Open
We calculate the spectral function of light quark flavours in 2+1 flavour vacuum QCD in the isospin-symmetric approximation. We employ spectral Dyson-Schwinger equations and compute the non-perturbative quark propagator directly in real-ti…
View article: Numerical fluid dynamics for FRG flow equations: Zero-dimensional QFTs as numerical test cases. II. Entropy production and irreversibility of RG flows
Numerical fluid dynamics for FRG flow equations: Zero-dimensional QFTs as numerical test cases. II. Entropy production and irreversibility of RG flows Open
We demonstrate that the reformulation of renormalization group (RG) flow equations as nonlinear heat equations has severe implications on the understanding of RG flows in general. We demonstrate by explicitly constructing an entropy functi…