TY  - JOUR
AU  - Papathanasiou, Georgios
AU  - Weinzierl, Stefan
AU  - Wu, Konglong
AU  - Zhang, Yang
TI  - Rationalisation of multiple square roots in Feynman integrals
JO  - Journal of high energy physics
VL  - 05
IS  - 5
SN  - 1126-6708
CY  - Heidelberg
PB  - Springer
M1  - PUBDB-2025-04375
M1  - arXiv:2501.07490
M1  - DESY-25-001
M1  - MITP-25-004
M1  - USTC-ICTS/PCFT-24-28
SP  - =78
PY  - 2025
N1  - 26 pages
AB  - Feynman integrals are very often computed from their differential equations. It is not uncommon that the ε-factorised differential equation contains only dlog-forms with algebraic arguments, where the algebraic part is given by (multiple) square roots. It is well-known that if all square roots are simultaneously rationalisable, the Feynman integrals can be expressed in terms of multiple polylogarithms. This is a sufficient, but not a necessary criterium. In this paper we investigate weaker requirements. We discuss under which conditions we may use different rationalisations in different parts of the calculation. In particular we show that we may use different rationalisations if they correspond to different parameterisations of the same integration path. We present a non-trivial example — the one-loop pentagon function with three adjacent massive external legs involving seven square roots — where this technique can be used to express the result in terms of multiple polylogarithms.
KW  - Electroweak Precision Physics (autogen)
KW  - Higher-Order Perturbative Calculations (autogen)
LB  - PUB:(DE-HGF)16
DO  - DOI:10.1007/JHEP05(2025)078
UR  - https://bib-pubdb1.desy.de/record/639274
ER  -