arXiv subjects
Publications and source records attributed to Gudrun Heinrich.
We study the effects of renormalisation group running for the Wilson coefficients of dimension-6 operators contributing to Higgs boson pair production in gluon fusion within Standard Model Effective Field Theory (SMEFT). The running of these Wilson coefficients has been implemented in the NLO QCD code ggHH_SMEFT, which is publicly available within the Powheg-Box-V2 framework.
The calculation of contributions from the chromomagnetic and four-top-quark-operators within Standard Model Effective Field Theory (SMEFT) to Higgs boson pair production in gluon fusion is presented, in combination with NLO QCD corrections. Here we focus on the $γ_5$-scheme dependence introduced by the four-top-quark-operators and the interplay with other operators contributing to this process in SMEFT.
We present the calculation of the contribtuions from the chromomagnetic and four-top-quark-operators within Standard Model Effective Field Theory (SMEFT) to Higgs boson pair production in gluon fusion, combined with full NLO QCD corrections. We study the effects of these operators on the total cross section and the invariant mass distribution of the Higgs-boson pair, at $\sqrt{s}=13.6$ TeV. These subleading operators are implemented in the generator ggHH_SMEFT, in the same Powheg-Box-V2 framework as the leading operators, such that their effects can be easily studied in a unified setup.
We present numerical results for the two-loop virtual amplitude entering the NNLO corrections to Higgs boson production in association with a top quark pair at the LHC, focusing, as a proof of concept of our method, on the part of the quark-initiated channel containing loops of massless or massive quarks. Results for the UV renormalised and IR subtracted two-loop amplitude for each colour structure are given at selected phase-space points and visualised in terms of surfaces as a function of two-dimensional slices of the full phase space.
We calculate the four-top quark operator contributions to Higgs production via gluon fusion in the Standard Model Effective Field Theory. The four-top operators enter for the first time via two-loop diagrams. Due to their chiral structure they contain $γ_5$, so special care needs to be taken when using dimensional regularisation for the loop integrals. We use two different schemes for the continuation of $γ_5$ to $D$ space-time dimensions in our calculations and present a mapping for the parameters in the two schemes. This generically leads to an interplay of different operators, such as four-top operators, chromomagnetic operators or Yukawa-type operators at the loop level. We validate our results by examples of matching onto UV models.
We discuss the combination of NLO QCD corrections with operators of canonical dimension six within Standard Model Effective Field Theory (SMEFT), as well as within non-linear Effective Field Theory (HEFT) for Higgs-boson pair production in gluon fusion. Particular emphasis will be put on the identification of leading and subleading operators contributing to this process.
We present a calculation of the NLO QCD corrections for Higgs-boson pair production in gluon fusion including effects of anomalous couplings within Standard Model Effective Field Theory (SMEFT). We study effects of different truncation options of the EFT expansion in $1/Λ$ and of double operator insertions, both at total cross-section level as well as for the distribution of the invariant mass of the Higgs-boson pair, at $\sqrt{s}=13$ TeV. The NLO corrections are implemented in the generator $\texttt{ggHH_SMEFT}$ in the $\texttt{Powheg-Box-V2}$ framework.
We present an update of the Universal FeynRules Output model format, commonly known as the UFO format, that is used by several automated matrix-element generators and high-energy physics software. We detail different features that have been proposed as extensions of the initial format during the last ten years, and collect them in the current second version of the model format that we coin the Universal Feynman Output format. Following the initial philosophy of the UFO, they consist of flexible and modular additions to address particle decays, custom propagators, form factors, the renormalisation group running of parameters and masses, and higher-order quantum corrections.
Numerical evaluations of Feynman integrals often proceed via a deformation of the integration contour into the complex plane. While valid contours are easy to construct, the numerical precision for a multi-loop integral can depend critically on the chosen contour. We present methods to optimize this contour using a combination of optimized, global complex shifts and a normalizing flow. They can lead to a significant gain in precision.
First-principle simulations are at the heart of the high-energy physics research program. They link the vast data output of multi-purpose detectors with fundamental theory predictions and interpretation. This review illustrates a wide range of applications of modern machine learning to event generation and simulation-based inference, including conceptional developments driven by the specific requirements of particle physics. New ideas and tools developed at the interface of particle physics and machine learning will improve the speed and precision of forward simulations, handle the complexity of collision data, and enhance inference as an inverse simulation problem.
This paper presents a comprehensive review of both the theory and experimental successes of Quantum Chromodynamics, starting with its emergence as a well defined theory in 1972-73 and following developments and results up to the present day. Topics include a review of the earliest theoretical and experimental foundations; the fundamental constants of QCD; an introductory discussion of lattice QCD, the only known method for obtaining exact predictions from QCD; methods for approximating QCD, with special focus on effective field theories; QCD under extreme conditions; measurements and predictions of meson and baryon states; a special discussion of the structure of the nucleon; techniques for study of QCD at high energy, including treatment of jets and showers; measurements at colliders; weak decays and quark mixing; and a section on the future, which discusses new experimental facilities or upgrades currently funded. The paper is intended to provide a broad background for Ph.D. students and postdocs starting their career. Some contributions include personal accounts of how the ideas or experiments were developed.
We present results for Higgs boson pair production in gluon fusion at next-to-leading order in QCD, including effects of anomalous couplings within Standard Model Effective Field Theory (SMEFT). In particular, we investigate truncation effects of the SMEFT series, comparing different ways to treat powers of dimension-six operators and double operator insertions.
We discuss recent progress in Standard Model predictions related to Higgs boson physics at the LHC and comment on the combination of higher order corrections with potential effects of heavy New Physics parametrised by Effective Field Theories.
We present the NLO (two-loop) QCD corrections to Higgs boson pair production in gluon fusion within Standard Model Effective Theory (SMEFT), including also squared dimension-6 operators and double insertions of operators. The different options to truncate the EFT expansion are contrasted to a non-linear EFT approach (HEFT) and their effects are illustrated by several phenomenological examples.
We present fully differential next-to-leading order results for Higgs production in association with a $Z$ boson in gluon fusion. Our two-loop virtual contributions are evaluated numerically using sector decomposition, including full top-quark mass effects, and supplemented at high $p_T$ by an analytic high-energy expansion to order ($m_Z^4, m_H^4, m_t^{32}$). Using the expanded results we also present a study of the top-quark mass scheme uncertainty at large $p_T$.
We combine NLO predictions with full top-quark mass dependence with approximate NNLO predictions for Higgs-boson pair production in gluon fusion, including the possibility to vary coupling parameters within a non-linear Effective Field Theory framework containing five anomalous couplings for this process. We study the impact of the anomalous couplings on various observables, and present Higgs-pair invariant-mass distributions at seven benchmark points characterising different $m_{hh}$ shape types. We also provide numerical coefficients for the approximate NNLO cross section as a function of the anomalous couplings at $\sqrt{s}=14$ TeV.
The precision frontier in collider physics is being pushed at impressive speed, from both the experimental and the theoretical side. The aim of this review is to give an overview of recent developments in precision calculations within the Standard Model of particle physics, in particular in the Higgs sector. While the first part focuses on phenomenological results, the second part reviews some of the techniques which allowed the rapid progress in the field of precision calculations. The focus is on analytic and semi-numerical techniques for multi-loop amplitudes, however fully numerical methods as well as subtraction schemes for infrared divergent real radiation beyond NLO are also briefly described.
We present results for the two-loop helicity amplitudes entering the NLO QCD corrections to the production of a Higgs boson in association with a $Z$-boson in gluon fusion. The two-loop integrals, involving massive top quarks, are calculated numerically. Results for the interference of the finite part of the two-loop amplitudes with the Born amplitude are shown as a function of the two kinematic invariants on which the amplitudes depend.