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Andreas von Manteuffel

Publications and source records attributed to Andreas von Manteuffel.

At least 37 records · Page 2Linked to original sources
arXiv2022

Renormalization of twist-two operators in QCD and its application to singlet splitting functions

Splitting functions govern the scale evolution of parton distribution functions. Through a Mellin transformation, they are related to anomalous dimensions of twist-two operators in the operator product expansion. We study off-shell operator matrix element, where the physical operators mix under renormalization with other gauge-variant operators of the same quantum numbers. We devise a new method to systematically extract the Feynman rules resulting from those operators without knowing the operators themselves. As a first application of the new approach, we independently reproduce the well-known three-loop singlet splitting functions obtained from computations of on-shell quantities.

hep-ph↗
arXiv2022

Three-loop helicity amplitudes for quark-gluon scattering in QCD

We compute the three-loop helicity amplitudes for $q\bar{q} \to gg$ and its crossed partonic channels, in massless QCD. Our analytical results provide a non-trivial check of the color quadrupole contribution to the infrared poles for external states in different color representations. At high energies, the $qg \to qg$ amplitude shows the predicted factorized form from Regge theory and confirms previous results for the gluon Regge trajectory extracted from $qq' \to qq'$ and $gg \to gg$ scattering.

hep-ph↗
arXiv2022

Computational challenges for multi-loop collider phenomenology

Precision measurements at the LHC and future colliders require theory predictions with uncertainties at the percent level for many observables. Theory uncertainties due to the perturbative truncation are particularly relevant and must be reduced to fully exploit the physics potential of collider experiments. In recent years the theoretical high energy physics community has made tremendous analytical and numerical advances to address this challenge. In this white paper, we survey state-of-the-art calculations in perturbative quantum field theory for collider phenomenology with a particular focus on the computational requirements at high perturbative orders. We show that these calculations can have specific high-performance-computing (HPC) profiles that should to be taken into account in future HPC resource planning.

hep-ph↗
arXiv2022

The $Hb\bar{b}$ vertex at four loops and hard matching coefficients in SCET for various currents

We compute the four-loop corrections to the Higgs-bottom vertex within massless QCD and present analytic results for all color structures. The infrared poles of the renormalized form factor agree with the predicted four-loop pattern. Furthermore, we use the results for the Higgs-bottom, photon-quark, and Higgs-gluon form factors to provide hard matching coefficients in soft-collinear effective theory up to four-loop accuracy.

hep-ph↗
arXiv2022

Three-loop helicity amplitudes for diphoton production in gluon fusion

We present a calculation of the helicity amplitudes for the process $gg\toγγ$ in three-loop massless QCD. We employ a recently proposed method to calculate scattering amplitudes in the 't Hooft-Veltman scheme that reduces the amount of spurious non-physical information needed at intermediate stages of the computation. Our analytic results for the three-loop helicity amplitudes are remarkably compact, and can be efficiently evaluated numerically. This calculation provides the last missing building block for the computation of NNLO QCD corrections to diphoton production in gluon fusion.

hep-ph↗
arXiv2022

Mixed QCD-electroweak corrections to dilepton production at the LHC in the high invariant mass region

We compute mixed QCD-electroweak corrections to the neutral-current Drell-Yan production of a pair of massless leptons in the high invariant mass region. Our computation is fully differential with respect to the final state particles. At relatively low values of the dilepton invariant mass, $m_{\ell \ell} \sim 200$ GeV, we find unexpectedly large mixed QCD-electroweak corrections at the level of -1%. At higher invariant masses, $m_{\ell \ell} \sim 1$ TeV, we observe that these corrections can be well approximated by the product of QCD and electroweak corrections. Hence, thanks to the well-known Sudakov enhancement of the latter, they increase at large invariant mass and reach e.g. -3% at $m_{\ell \ell} = 3$ TeV. Finally, we note that the inclusion of mixed corrections reduces the theoretical uncertainty related to the choice of electroweak input parameters to below the percent level.

hep-ph↗
arXiv2022

Quark and gluon form factors in four-loop QCD

We compute the photon-quark and Higgs-gluon form factors to four-loop order within massless perturbative Quantum Chromodynamics. Our results constitute ready-to-use building blocks for N${}^4$LO cross sections for Drell-Yan processes and gluon-fusion Higgs boson production at the LHC. We present complete analytic expressions for both form factors and show several of the most complicated master integrals.

hep-ph↗
arXiv2021

The Four-Loop $\mathcal{N}=4$ SYM Sudakov Form Factor

We present the Sudakov form factor in full color $\mathcal{N}=4$ supersymmetric Yang-Mills theory to four loop order and provide uniformly transcendental results for the relevant master integrals through to weight eight.

hep-th↗
arXiv2021

Fermionic corrections to quark and gluon form factors in four-loop QCD

We analytically compute all four-loop QCD corrections to the photon-quark and Higgs-gluon form factors involving a closed massless fermion loop. Our calculation of non-planar vertex integrals confirms a previous conjecture for the analytical form of the non-fermionic contributions to the collinear anomalous dimensions of quarks and gluons.

hep-ph↗
arXiv2021

Two-loop helicity amplitudes for diphoton plus jet production in full color

We present the complete two-loop corrections in massless QCD for the production of two photons and a jet, taking into account all color structures. In particular, we analytically compute all two-loop helicity amplitudes for the quark-antiquark, quark-gluon, and antiquark-gluon channel, and check them with an independent calculation of the polarization-summed interference with the tree amplitude. This is the first time that two-loop QCD corrections to a five-point scattering process have been computed beyond the leading-color approximation for all helicity configurations.

hep-ph↗
arXiv2021

Two-loop helicity amplitudes for $gg \to ZZ$ with full top-quark mass effects

We calculate the two-loop QCD corrections to $gg \to ZZ$ involving a closed top-quark loop. We present a new method to systematically construct linear combinations of Feynman integrals with a convergent parametric representation, where we also allow for irreducible numerators, higher powers of propagators, dimensionally shifted integrals, and subsector integrals. The amplitude is expressed in terms of such finite integrals by employing syzygies derived with linear algebra and finite field techniques. Evaluating the amplitude using numerical integration, we find agreement with previous expansions in asymptotic limits and provide ab initio results also for intermediate partonic energies and non-central scattering at higher energies.

hep-ph↗
arXiv2021

Two-loop leading colour QCD corrections to $q \bar{q} \to γγg$ and $q g \to γγq$

We present the leading colour and light fermionic planar two-loop corrections for the production of two photons and a jet in the quark-antiquark and quark-gluon channels. In particular, we compute the interference of the two-loop amplitudes with the corresponding tree level ones, summed over colours and polarisations. Our calculation uses the latest advancements in the algorithms for integration-by-parts reduction and multivariate partial fraction decomposition to produce compact and easy-to-use results. We have implemented our results in an efficient C++ numerical code. We also provide their analytic expressions in Mathematica format.

hep-ph↗
arXiv2021

MultivariateApart: Generalized Partial Fractions

We present a package to perform partial fraction decompositions of multivariate rational functions. The algorithm allows to systematically avoid spurious denominator factors and is capable of producing unique results also when being applied to terms of a sum separately. The package is designed to work in Mathematica, but also provides interfaces to the Form and Singular computer algebra systems.

cs.SC↗
arXiv2020

Mixed EW-QCD two-loop amplitudes for $q\bar{q} \to \ell^+\ell^-$ and $γ_5$ scheme independence of multi-loop corrections

We perform a dedicated study of the $q \bar{q}$-initiated two-loop electroweak-QCD Drell-Yan scattering amplitude in dimensional regularization schemes for vanishing light quark and lepton masses. For the relative order $α$ and $α_s$ one-loop Standard Model corrections, details of our comparison to the original literature are given. The infrared pole terms of the mixed two-loop amplitude are governed by a known generalization of the dipole formula and we show explicitly that exactly the same two-loop polarized hard scattering functions are obtained in both the standard 't Hooft-Veltman-Breitenlohner-Maison $γ_5$ scheme and Kreimer's anticommuting $γ_5$ scheme.

hep-ph↗
arXiv2020

Di-photon amplitudes in three-loop Quantum Chromodynamics

We consider the three-loop scattering amplitudes for the production of a pair of photons in quark-antiquark annihilation in Quantum Chromodynamics (QCD). We use suitably defined projectors to efficiently calculate all helicity amplitudes. We obtain relatively compact analytic results, that we write in terms of harmonic polylogarithms or, alternatively, multiple polylogarithms of up to depth three. This is the first calculation of a three-loop four-point scattering amplitude in full QCD.

hep-ph↗
arXiv2020

Multiple polylogarithms with algebraic arguments and the two-loop EW-QCD Drell-Yan master integrals

We consider Feynman integrals with algebraic leading singularities and total differentials in $ε\,\mathrm{d}\ln$ form. We show for the first time that it is possible to evaluate integrals with singularities involving unrationalizable roots in terms of conventional multiple polylogarithms, by either parametric integration or matching the symbol. As our main application, we evaluate the two-loop master integrals relevant to the $αα_s$ corrections to Drell-Yan lepton pair production at hadron colliders. We optimize our functional basis to allow for fast and stable numerical evaluations in the physical region of phase space.

hep-th↗
arXiv2020

Cusp and collinear anomalous dimensions in four-loop QCD from form factors

We calculate the complete quark and gluon cusp anomalous dimensions in four-loop massless QCD analytically from first principles. In addition, we determine the complete matter dependence of the quark and gluon collinear anomalous dimensions. Our approach is to Laurent expand four-loop quark and gluon form factors in the parameter of dimensional regularization. We employ finite field and syzygy techniques to reduce the relevant Feynman integrals to a basis of finite integrals, and subsequently evaluate the basis integrals directly from their standard parametric representations.

hep-ph↗