arXiv subjects

Tobias Theil

Publications and source records attributed to Tobias Theil.

4 recordsLinked to original sources

arXiv2025

Infrared Anomalous Dimensions at Three-Loop in the SM from Conserved Currents

We study the infrared structure of the Standard Model (SM) restricted to the first generation of fermions, including the full SM gauge group, up to three-loop order, and determine the resulting cusp and collinear anomalous dimensions for all gauge groups and particles of the theory. We observe that starting from three loops, the resulting cusp anomalous dimensions include terms involving two distinct couplings, contrary to previous claims in the literature. We give a detailed explanation of this observation and explore the origin of these terms. We provide a supplementary file where all infrared anomalous dimensions calculated in this work are collected. Our results are consistent with the existing literature wherever comparisons are possible.

hep-ph↗

arXiv2023

Two-Loop Infrared Renormalization with On-shell Methods

Within the framework proposed by Caron-Huot and Wilhelm, we give a recipe for computing infrared anomalous dimensions purely on-shell, efficiently up to two loops in any massless theory. After introducing the general formalism and reviewing the one-loop recipe, we extract a practical formula that relates two-loop infrared anomalous dimensions to certain two- and three-particle phase space integrals with tree-level form factors of conserved operators. We then provide several examples of the use of the two-loop formula and comment on some of its formal aspects, especially the cancellation of 'one-loop squared' spurious terms. The present version of the paper is augmented with a detailed treatment of the structure of infrared divergences in massless theories of scalars and fermions up to two loops. In the calculation we encounter divergent phase space integrals and show in detail how these cancel among each other as required by the finiteness of the anomalous dimension. As a non-trivial check of the method, we also perform the computation with a standard diagrammatic approach, finding perfect agreement.

hep-th↗

arXiv2023

Electric dipole moments at one-loop in the dimension-6 SMEFT

In this paper we present the complete expressions of the lepton and neutron electric dipole moments (EDMs) in the Standard Model Effective Field Theory (SMEFT), up to 1-loop and dimension-6 level and including both RG running contributions and finite corrections. The latter play a fundamental role in the cases of operators that do not renormalize the dipoles, but there are also classes of operators for which they provide an important fraction, $10-20\%$, of the total 1-loop contribution, if the new physics scale is around $Λ=5$ TeV. We present the full set of bounds on each individual Wilson coefficient contributing to the EDMs using both the current experimental constraints, as well as those from future experiments, which are expected to improve by at least an order of magnitude.

hep-ph↗

arXiv2021

The Present and Future of Four Top Operators

We study the phenomenology of a strongly-interacting top quark at future hadron and lepton colliders, showing that the characteristic four-top contact operators give rise to the most significant effects. We demonstrate the extraordinary potential of a 100 TeV proton-proton collider to directly test such non-standard interactions in four-top production, a process that we thoroughly analyze in the same-sign dilepton and trilepton channels, and explore in the fully hadronic channel. Furthermore, high-energy electron-positron colliders, such as CLIC or the ILC, are shown to exhibit an indirect yet remarkable sensitivity to four-top operators, since these constitute, via renormalization group evolution, the leading new-physics deformations in top-quark pair production. We investigate the impact of our results on the parameter space of composite Higgs models with a strongly-coupled (right-handed) top quark, finding that four-top probes provide the best sensitivity on the compositeness scale at the future energy frontier. In addition, we investigate mild yet persisting LHC excesses in multilepton plus jets final states, showing that they can be consistently described in the effective field theory of such a new-physics scenario.

hep-ph↗