A5033101193- Quantum Chromodynamics and Particle Interactions
- Particle physics theoretical and experimental studies
- High-Energy Particle Collisions Research
- Black Holes and Theoretical Physics
- Cold Atom Physics and Bose-Einstein Condensates
- Theoretical and Computational Physics
- Cosmology and Gravitation Theories
- Physics of Superconductivity and Magnetism
- Noncommutative and Quantum Gravity Theories
- Quantum many-body systems
- Quantum, superfluid, helium dynamics
- Atomic and Subatomic Physics Research
- Quantum chaos and dynamical systems
- Pulsars and Gravitational Waves Research
- Topological Materials and Phenomena
- Markov Chains and Monte Carlo Methods
- Algebraic structures and combinatorial models
- Topological and Geometric Data Analysis
- Dark Matter and Cosmic Phenomena
- Quantum Mechanics and Applications
- Numerical methods for differential equations
- Advanced NMR Techniques and Applications
- Advanced Topics in Algebra
- Advanced Thermodynamics and Statistical Mechanics
- Nonlinear Waves and Solitons
Heidelberg University
2016-2025
GSI Helmholtz Centre for Heavy Ion Research
2014-2024
Heidelberg Institute for Theoretical Studies
2012-2024
Instituto de Física Teórica
2024
Laboratoire d'Informatique de l'École Polytechnique
2024
Centre National de la Recherche Scientifique
2024
TU Wien
2024
Max Planck Institute for Nuclear Physics
2023
Bielefeld University
2020
Psykiatrien i Region Syddanmark
2020
The relation between the deconfinement and chiral phase transition is explored in framework of a Polyakov-loop-extended two-flavor quark-meson (PQM) model. In this model Polyakov loop dynamics represented by background temporal gauge field which also couples to quarks. As novelty an explicit quark chemical potential ${N}_{f}$-dependence proposed using renormalization group arguments. behavior as well condensate function temperature obtained minimizing grand canonical thermodynamic system....
We relate quark confinement, as measured by the Polyakov-loop order parameter, to colour described Kugo–Ojima/Gribov–Zwanziger scenario. identify a simple criterion for confinement based on IR behaviour of ghost and gluon propagators, compute order-parameter potential from knowledge Landau-gauge correlation functions with aid functional RG. Our approach predicts deconfinement transition in quenched QCD be first SU(3) second SU(2) – agreement general expectations. As an estimate critical...
We discuss the phase structure of QCD for ${N}_{f}=2$ and ${N}_{f}=2+1$ dynamical quark flavors at finite temperature baryon chemical potential. It emerges dynamically from underlying fundamental interactions between quarks gluons in our work. To this end, starting perturbative high-energy regime, we systematically integrate out quantum fluctuations toward low energies by using functional renormalization group. By hadronizing dominant interaction channels responsible formation light mesons...
The Polyakov-extended quark–meson model (PQM) is investigated beyond mean-field. This represents an important step towards a fully dynamical QCD computation. Both the quantum fluctuations to matter sector and back-reaction of Yang–Mills are included. Results on chiral confinement–deconfinement crossover/phase transition lines location possible critical endpoint presented. Moreover, thermodynamic quantities such as pressure quark density discussed.
We present a quantitative analysis of chiral symmetry breaking in two-flavor continuum QCD the quenched limit. The theory is set up at perturbative momenta, where asymptotic freedom leads to precise results. evolution towards hadronic phase achieved by means dynamical hadronization nonperturbative functional renormalization group approach. use vertex expansion scheme based on gauge-invariant operators and discuss its convergence properties remaining systematic errors. In particular, we...
We investigate Landau gauge $SU(3)$ Yang-Mills theory in a systematic vertex expansion scheme for the effective action with functional renormalization group. Particular focus is put on dynamical creation of gluon mass gap at nonperturbative momenta and consistent treatment quadratic divergences. The ghost transverse propagators as well momentum-dependent ghost-gluon, three-gluon four-gluon vertices are calculated self-consistently classical only input. apparent convergence discussed within...
We present nonperturbative first-principle results for quark, gluon, and meson 1PI correlation functions of two-flavor Landau-gauge QCD in the vacuum. These carry full information about theory. They are obtained by solving their functional renormalization group equations a systematic vertex expansion, aiming at apparent convergence. This work represents crucial prerequisite quantitative studies phase diagram hadron spectrum within this framework. In particular, we have computed ghost,...
Asymptotic safety is a theoretical proposal for the ultraviolet completion of quantum field theories, in particular gravity. Significant progress on this program has led to first characterization Reuter fixed point. Further advancement our understanding nature spacetime requires addressing number open questions and challenges. Here, we aim at providing critical reflection state art asymptotic program, specifying elaborating both technical conceptual nature. We also point out systematic...
We reconstruct the Lorentzian graviton propagator in asymptotically safe quantum gravity from Euclidean data. The reconstruction is applied to both dynamical fluctuation and background propagator. prove that spectral function of latter necessarily has negative parts similar to, for same reasons, as gluon function. In turn, positive. argue enters cross sections other observables gravity. Hence, its positivity may hint at unitarity
We present the first direct and nonperturbative computation of graviton spectral function in quantum gravity. This is achieved with help a novel Lorentzian renormalization group approach, combined representation correlation functions. find positive function, showing massless one-graviton peak multigraviton continuum an asymptotically safe scaling for large values. also study impact cosmological constant. Further steps to investigate scattering processes unitarity gravity are indicated.
We investigate the infrared behaviour of gluon and ghost propagators in Landau gauge QCD by means an exact renormalisation group equation. explain how, general, momentum structure Green functions can be extracted within this approach. An optimisation procedure is devised to remove residual regulator dependences. In framework used determine leading terms propagators. The results support Kugo-Ojima confinement scenario. Possible extensions are discussed.
We study the phase diagram of QCD with help order parameters for chiral symmetry breaking and quark confinement. also introduce a new parameter confinement transition, which is related to density. It easily accessible by different theoretical approaches, such as functional approaches or lattice simulations. Its relation Polyakov loop expectation value discussed analysed. Our results suggest close between transition.
We present an analysis of the dynamics two-flavor QCD in vacuum. Special attention is paid to transition from high-energy quark-gluon regime low-energy governed by hadron dynamics. This done within a functional renormalization group approach amended dynamical hadronization techniques. These techniques allow us describe conveniently perturbative nonperturbative limit without suffering fine-tuning model parameters. In work, we apply these with physical quark masses and show how dominant...
The phase diagram of four-dimensional Einstein–Hilbert gravity is studied using Wilson's renormalization group. Smooth trajectories connecting the ultraviolet fixed point at short distances with attractive infrared points long are derived from non-perturbative graviton propagator. Implications for asymptotic safety conjecture and further results discussed.
We study the ultraviolet stability of gravity-matter systems for general numbers minimally coupled scalars and fermions. This is done within functional renormalization group setup put forward in [N. Christiansen, B. Knorr, J. Meibohm, M. Pawlowski, Reichert, Phys. Rev. D 92, 121501 (2015).] pure gravity. It includes full dynamical propagators a genuine Newton's coupling, which extracted from graviton three-point function. find gravity-fermion systems. Gravity-scalar are also found to be...
We investigate the ultraviolet behavior of quantum gravity within a functional renormalization group approach. The present setup includes full ghost and graviton propagators and, for first time, dynamical three-point function. latter gives access to coupling gravitons makes system minimally self-consistent. resulting phase diagram confirms asymptotic safety scenario in with nontrivial UV fixed point. A well-defined Wilsonian block spinning requires locality flow momentum space. This property...
We study four-dimensional quantum gravity using nonperturbative renormalization group methods. solve the corresponding equations for fully momentum-dependent propagator, Newtons coupling and cosmological constant. For first time, we obtain a global phase diagram where non-Gaussian ultraviolet fixed point of asymptotic safety is connected via smooth trajectories to classical infrared point. The theory therefore complete deforms smoothly into as limit approached.
We investigate the effects of strong magnetic fields on QCD phase structure at vanishing density by solving gluon and quark gap equations, studying dynamics scattering with four-Fermi coupling. The chiral crossover temperature as well condensate are computed. For asymptotically large we find catalysis, while inverse catalysis for intermediate fields. Moreover, transition massless quarks turns into a crossover. underlying mechanisms then investigated analytically within few simplifications...
We present a shortened and simplified version of our proof [C. S. Fischer J. M. Pawlowski, Phys. Rev. D 75, 025012 (2007).] the uniqueness scaling solution for infrared asymptotics Green functions in Landau gauge Yang-Mills theory. The simplification relates to new renormalization group--invariant arrangement applicable general theories. As before relies on necessary consistency between Dyson-Schwinger equations functional group equations. also demonstrate existence specific both, equations,...
The asymptotic safety scenario in gravity is accessed within the systematic vertex expansion scheme for functional renormalisation group flows put forward Christiansen et al. (Phys Lett B 728:114, 2014), (Phy Rev D 93:044036, 2016), and implemented 92:121501, 2015) propagators three-point functions. In present work this extended to dynamical graviton four-point function. For first time, provides us with a closed flow equation propagator: all vertices involved are computed from their own...