Vacuum expectation value renormalization in the standard model and beyond

We show how the renormalization constant of the Higgs vacuum expectation value fixed by a tadpole condition is responsible for gauge dependences in various definitions of parameters in the R$_{E}$ -gauge. Then we show the relationship of this renormalization constant to the Fleischer-Jegerlehner (FJ) scheme, which is used to avoid these gauge dependences. In this way, we also present a viewpoint on the FJ scheme complementary to the ones already existing in the literature. Additionally, we compare and discuss different approaches to the renormalization of tadpoles by identifying the similarities and relations between them. The relationship to the Higgs background-field renormalization is also discussed

Renormalization of the multi-Higgs-doublet Standard Model and one-loop lepton mass corrections

Motivated by models for neutrino masses and lepton mixing, we consider the renormalization of the lepton sector of a general multi-Higgs-doublet Standard Model with an arbitrary number of right-handed neutrino singlets. We propose to make the theory finite by \overline{\mbox{MS}} renormalization of the parameters of the unbroken theory. However, using a general $R_\xi$ gauge, in the explicit one-loop computations of one-point and two-point functions it becomes clear that---in addition---a renormalization of the vacuum expectation values (VEVs) is necessary. Moreover, in order to ensure vanishing one-point functions of the physical scalar mass eigenfields, finite shifts of the tree-level VEVs, induced by the finite parts of the tadpole diagrams, are required. As a consequence of our renormalization scheme, physical masses are functions of the renormalized parameters and VEVs and thus derived quantities. Applying our scheme to one-loop corrections of lepton masses, we perform a thorough discussion of finiteness and $\xi$-independence. In the latter context, the tadpole contributions figure prominently.Comment: 50 pages. Minor typos corrected. Matches version in JHE

Vacuum expectation value renormalization in the Standard Model and beyond

We show how the renormalization constant of the Higgs vacuum expectation value, fixed by a tadpole condition, is responsible for gauge dependences in various definitions of parameters in the $R_{\xi}$-gauge. Then we show the relationship of this renormalization constant to the Fleischer-Jegerlehner (FJ) scheme, which is used to avoid these gauge dependences. In this way, we also present a viewpoint on the FJ-scheme complementary to the ones already existing in the literature. Additionally, we compare and discuss different approaches to the renormalization of tadpoles by identifying the similarities and relations between them. The relationship to the Higgs background field renormalization is also discussed.Comment: 16 pages; accepted for publication in pr

Leaks of CP violation in the real two-Higgs doublet model

We discuss the $Z_2$ symmetric two Higgs doublet model with a real soft breaking term (real 2HDM). We explain in detail why it is not tenable to assume CP conservation in the scalar sector to keep the dimension two term real, while CP is violated by the dimension four Yukawa couplings. We propose the calculation of the infinite tadpole of the (would-be) pseudoscalar neutral scalar. We construct a simple toy model with the same flaws, where the unrenormalizable infinity is easier to calculate. We then turn our attention to the same tadpole in the real 2HDM. We spearhead this effort focusing on diagrams involving solely bare quantities. This involves hundreds of Feynman three-loop diagrams that could feed the CP violation from the quark into the scalar sector, and is only possible with state of the art automatic computation tools. Remarkably, some intermediate results agree when using three independent derivations, including the peculiar cancellation of the leading pole divergence due to a subtle interplay between masses and the Jarlskog invariant, which we calculate analytically. The calculation is not complete however, since the full two-loop renormalization of the real 2HDM is not yet available in the literature. Still, we argue convincingly that there is an irremovable infinity.Comment: 12 pages, matches published versio

Leaks of CP violation in the real two-Higgs-doublet model

We discuss the Z$_{2}$ symmetric two-Higgs-doublet model with a real soft-breaking term (real 2HDM). We explain in detail why it is not tenable to assume CP conservation in the scalar sector to keep the dimension two term real, while CP is violated by the dimension four Yukawa couplings. We propose the calculation of the infinite tadpole of the (would-be) pseudoscalar neutral scalar. We construct a simple toy model with the same flaws, where the unrenormalizable infinity is easier to calculate. We then consider the same tadpole in the real 2HDM. We spearhead this effort focusing on diagrams involving solely bare quantities. This involves hundreds of Feynman three-loop diagrams that could feed the CP violation from the quark into the scalar sector, and is only possible with state of the art automatic computation tools. Remarkably, some intermediate results agree when using three independent derivations, including the peculiar cancellation of the leading pole divergence due to a subtle interplay between masses and the Jarlskog invariant, which we calculate analytically. The calculation is not complete however, since the full two-loop renormalization of the real 2HDM is not yet available in the literature. Still, we argue convincingly that there is an irremovable infinity

New developments on the WHIZARD event generator

We give a status report on new developments in the WHIZARD event generator, including NLO electroweak automation for $e^+e^-$ colliders, loop-induced processes, POWHEG matching, new features in the UFO interface and the current development for matching between exclusive photon radiation and fixed-order LO/NLO electroweak (EW) corrections. We report on several bug fixes relevant for certain aspects of the ILC250 Monte Carlo (MC) mass production, especially on the normalization of matching EPA samples with full-matrix element samples. Finally, we mention some ongoing work on efficiency improvements regarding parallelization of matrix elements and phase space sampling, as well as plans to revive the top threshold simulation.Comment: Talk presented at the International Workshop on Future Linear Colliders (LCWS 2023), 15-19 May 2023. C23-05-15.

Multi-Emission Kernels for Parton Branching Algorithms

We introduce a general framework to construct multi-emission kernels for parton branching algorithms at the amplitude level and across different soft and collinear limits. We highlight the connection of kinematic parameterizations and recoil schemes to the underlying power counting, and discuss in detail how soft radiation can be partitioned in between different collinear configurations beyond the single-emission picture underpinning the traditional dipole and angular ordering approaches. Our work is a vital cornerstone to build parton branching algorithms which include multiply-unresolved emissions in a fully differential way, and our construction can also be used to obtain splitting functions for probabilistic algorithms or other cross-section level objects such as subtraction terms

Renormalization and one-loop corrections of lepton masses

Eine Vielzahl physikalischer Modelle, die versuchen, die experimentell bekannten Muster in Leptonmassen und Mischungswinkeln zu erklären, wurde im Laufe der letzten zwei Jahrzehnte erschaffen—viele davon inspiriert durch die reiche Phänomenologie des Neutrino-Sektors. In vielen Fällen sind radiative Korrekturen zu den Vorhersagen auf Baumgraphen-Niveau für Observablen nicht bekannt oder systematisch diskutiert. Aus diesem Grund haben wir ein vielseitig einsetzbares Werkzeug entwickelt um die störungstheoretische Stabilität solcher Vorhersagen in einer Vielzahl von Modellen untersuchen zu können. Alle für uns relevanten Modelle enthalten einen erweiterten skalaren Sektor und in vielen Fällen zusätzlich Majorana-Neutrinos. Deshalb haben wir unsere Untersuchungen im Rahmen des Multi-Higgs Doublet Standard Modells mit beliebiger Anzahl an Higgs-Doublets und rechtshändigen Majorana-Neutrinos durchgeführt. Unsere Arbeit besteht aus eingehenden Diskussionen der MSquer-Renormierung jenes allgemeinen Modells, der Behandlung von sog. Tadpole-Beiträgen im Zusammenhang mit Eichparameterabhängigkeiten, der Renormierung von Vakuumerwartungswerten und einer Präsentation der vollständigen analytischen Ein-Schleifen-Ergebnisse der Korrekturen zu den Leptonmassen. Zusätzlich sind unsere früheren Arbeiten gezeigt, in denen die Methoden entwickelt wurden, um zu besagten Resultaten zu gelangen. Diese Arbeiten enthalten eine neuartige Art sog. on-shell-Renormierungsbedingungen in einer allgemein gefassten Theorie herzuleiten, sowie die Diskussion eines Spielzeugmodells, das bereits viele der auszeichnenden Merkmale des zuletzt studierten realistischen Modells aufzeigt.An abundance of models trying to explain the patterns in lepton masses and mixings has been created over the past few decades—many of them inspired by the rich phenomenology of the neutrino sector. In many cases, radiative corrections to the tree-level predictions for observables in such models are unknown or have not been studied systematically so far. Therefore, we have developed a generally applicable setup for studying radiative corrections in a variety of models in order to check the perturbative stability of their predictions. All of the models referred to inherit an extended scalar sector and oftentimes Majorana neutrinos. Therefore, we performed our studies in the Multi-Higgs Standard Model with an arbitrary number of Higgs doublets and right-handed Majorana neutrinos. Our work consists of exhaustive discussions on the MS-renormalization of this general model, the treatment of tadpole contributions in terms of gauge-parameter dependencies, the renormalization of vacuum expectation values and a presentation of the complete analytic one-loop results for lepton mass corrections. Additionally, we present our earlier works in which we developed the methods for acquiring the mentioned results. These works contain a novel way of deriving on-shell renormalization conditions in a general setup and the discussion of a toy model which already exhibits some of the important features of our main study

Investigations on the Potential of 5G for the Detection of Wear in Industrial Roller-Burnishing Processes

Roller burnishing represents an economical alternative to conventional surface-finishing processes, such as fine turning or honing. In contrast to the well-known wear mechanisms of chip-forming processes, the wear behavior in roller-burnishing is strongly based on the experience of the machine operators. The nature of the finishing process makes roller-burnishing very sensitive to surface defects, as it is often not possible to rework the last step in a process chain. In the present work, a prototype for a smart roller-burnishing tool with 5G communication is presented, which serves as an inline-monitoring tool to detect tool wear. A suitable metric to monitor the tool wear of the manufacturing roll is suggested, and the potentials of 5G communication for the described use-case are evaluated. Based on the signal-to-noise ratio of the process-force, a metric is found that distinguishes new rolls from worn rolls with very small defects on the micrometer scale. Using the presented approach, it was possible to distinguish the signal-to-noise ratio of a roll with very small wear marks by 3.8% on average. In the case of stronger wear marks, on the order of 20 µm, the difference increased to up to 15.6%

Investigations on the Potential of 5G for the Detection of Wear in Industrial Roller-Burnishing Processes

Roller burnishing represents an economical alternative to conventional surface-finishing processes, such as fine turning or honing. In contrast to the well-known wear mechanisms of chip-forming processes, the wear behavior in roller-burnishing is strongly based on the experience of the machine operators. The nature of the finishing process makes roller-burnishing very sensitive to surface defects, as it is often not possible to rework the last step in a process chain. In the present work, a prototype for a smart roller-burnishing tool with 5G communication is presented, which serves as an inline-monitoring tool to detect tool wear. A suitable metric to monitor the tool wear of the manufacturing roll is suggested, and the potentials of 5G communication for the described use-case are evaluated. Based on the signal-to-noise ratio of the process-force, a metric is found that distinguishes new rolls from worn rolls with very small defects on the micrometer scale. Using the presented approach, it was possible to distinguish the signal-to-noise ratio of a roll with very small wear marks by 3.8% on average. In the case of stronger wear marks, on the order of 20 µm, the difference increased to up to 15.6%