TY - JOUR
T1 - Numerical renormalization-group-based approach to secular perturbation theory
AU - Gálvez Ghersi, José T.
AU - Stein, Leo C.
N1 - Publisher Copyright:
© 2021 American Physical Society
PY - 2021/9
Y1 - 2021/9
N2 - Perturbation theory is a crucial tool for many physical systems, when exact solutions are not available, or nonperturbative numerical solutions are intractable. Naive perturbation theory often fails on long timescales, leading to secularly growing solutions. These divergences have been treated with a variety of techniques, including the powerful dynamical renormalization group (DRG). Most of the existing DRG approaches rely on having analytic solutions up to some order in perturbation theory. However, sometimes the equations can only be solved numerically. We reformulate the DRG in the language of differential geometry, which allows us to apply it to numerical solutions of the background and perturbation equations. This formulation also enables us to use the DRG in systems with background parameter flows and, therefore, extend our results to any order in perturbation theory. As an example, we apply this method to calculate the soliton-like solutions of the Korteweg-de Vries equation deformed by adding a small damping term. We numerically construct DRG solutions which are valid on secular timescales, long after naive perturbation theory has broken down.
AB - Perturbation theory is a crucial tool for many physical systems, when exact solutions are not available, or nonperturbative numerical solutions are intractable. Naive perturbation theory often fails on long timescales, leading to secularly growing solutions. These divergences have been treated with a variety of techniques, including the powerful dynamical renormalization group (DRG). Most of the existing DRG approaches rely on having analytic solutions up to some order in perturbation theory. However, sometimes the equations can only be solved numerically. We reformulate the DRG in the language of differential geometry, which allows us to apply it to numerical solutions of the background and perturbation equations. This formulation also enables us to use the DRG in systems with background parameter flows and, therefore, extend our results to any order in perturbation theory. As an example, we apply this method to calculate the soliton-like solutions of the Korteweg-de Vries equation deformed by adding a small damping term. We numerically construct DRG solutions which are valid on secular timescales, long after naive perturbation theory has broken down.
UR - http://www.scopus.com/inward/record.url?scp=85116506668&partnerID=8YFLogxK
U2 - 10.1103/PhysRevE.104.034219
DO - 10.1103/PhysRevE.104.034219
M3 - Article
C2 - 34654117
AN - SCOPUS:85116506668
SN - 2470-0045
VL - 104
JO - Physical Review E
JF - Physical Review E
IS - 3
M1 - 034219
ER -