arXiv subjects

Gábor Somogyi

Publications and source records attributed to Gábor Somogyi.

At least 19 recordsLinked to original sources

arXiv2026

NNLOCAL: Fully Local Subtractions for Precision Predictions in Hadron Collisions

This work extends the CoLoRFulNNLO subtraction method to address soft and collinear divergences in the computation of higher-order corrections for hadronic collisions. By utilizing universal local counterterms which can be integrated analytically over the unresolved phase space, we achieve numerically stable, fully-differential predictions. Our publicly available NNLOCAL code serves as a proof-of-concept implementation, validated by calculating the NNLO cross-section for Higgs boson production in gluon-gluon fusion with no light quarks.

hep-ph↗

arXiv2026

NNLOCAL: Completely Local Subtractions

The computation of higher-order corrections to cross sections relevant at LHC involves the evaluation of phase-space integrals that exhibit soft and collinear divergences. The subtraction of these divergences is a key ingredient to obtain fully-differential predictions for physical observables. We discuss a subtraction method to handle these divergences based on the construction of universal local counterterms. The integration of the counterterms is carried out analytically, giving a strong control on the numerical stability of our predictions. We implement our method in a numerical program, that we dub NNLOCAL, and validate it by computing the fully-differential NNLO cross-section for Higgs boson production in gluon-gluon fusion.

hep-ph↗

arXiv2025

CoLoRFulNNLO for hadron collisions: regularizing initial-state double real emissions

We present the extension of the completely local subtraction scheme CoLoRFulNNLO to color-singlet production in hadron collisions. We provide explicit momentum mappings and the complete set of double-real counterterms required for this class of processes. The counterterms are systematically derived from the known infrared limit formulae of QCD matrix elements, and particular care has been taken to ensure their analytic integrability. The resulting construction involves a relatively small number of counter-events, preserving the locality and efficiency of the scheme. All formulae have been implemented within the publicly available NNLOCAL Monte Carlo program, and we explicitly validate all IR limits using arbitrary-precision computer algebra and present representative results. The counterterms presented here constitute a self-contained subset applicable to general hadronic processes within the CoLoRFulNNLO approach.

hep-ph↗

arXiv2024

LinApart: optimizing the univariate partial fraction decomposition

We present LinApart, a routine designed for efficiently performing the univariate partial fraction decomposition of large symbolic expressions. Our method is based on an explicit closed formula for the decomposition of rational functions with fully factorized denominators. We provide implementations in both the Wolfram Mathematica and C languages, made available at https://github.com/fekeshazy/LinApart . The routine can provide very significant performance gains over available tools such as the Apart command in Mathematica.

cs.SC↗

arXiv2021

Determination of $α_{S}$ beyond $NNLO$ using the event shape averages

In this proceedings we discuss a prescription to extract the QCD strong coupling constant at $N^{3}LO$ precision in perturbative QCD using a combination of ${\cal{O}}(α_{S}^{3})$ calculations in pQCD and estimations of the ${\cal{O}}(α_{S}^{4})$ corrections from the data. The method is applied to a set of event shape averages measured in experiments at the LEP, PETRA, PEP and TRISTAN colliders. In our analysis we account for hadronization effects with models from modern Monte Carlo event generators and analytic hadronization models. We conclude that the precision of the $α_{S}$ extraction cannot be improved significantly only with pQCD predictions of higher orders, and further progress in these studies requires a significant advances in the studies and modeling of hadronization process.

hep-ph↗

arXiv2021

Determination of $α_{S}$ beyond NNLO using event shape averages

We consider a method for determining the QCD strong coupling constant using fits of perturbative predictions for event shape averages to data collected at the LEP, PETRA, PEP and TRISTAN colliders. To obtain highest accuracy predictions we use a combination of perturbative ${\cal{O}}(α_{S}^{3})$ calculations and estimations of the ${\cal{O}}(α_{S}^{4})$ perturbative coefficients from data. We account for non-perturbative effects using modern Monte Carlo event generators and analytic hadronization models. The obtained results show that the total precision of the $α_{S}$ determination cannot be improved significantly with the higher order perturbative QCD corrections alone, but primarily requires a deeper understanding of the non-perturbative effects.

hep-ph↗

arXiv2020

Fully exclusive heavy quark-antiquark pair production from a colourless initial state at NNLO in QCD

We present a local subtraction scheme for computing next-to-next-to-leading order QCD corrections to the production of a massive quark-antiquark pair from a colourless initial state. The subtraction terms are built following the CoLoRFulNNLO method and refined in such a way that their integration gives rise to compact, fully analytic expressions. All ingredients necessary for a numerical implementation of our subtraction scheme are provided in detail. As an example, we calculate the fully differential decay rate of the Standard Model Higgs boson to massive bottom quarks at next-to-next-to-leading order accuracy in perturbative QCD.

hep-ph↗

arXiv2019

High precision determination of $α_s$ from a global fit of jet rates

We present state-of-the-art extractions of the strong coupling based on N$^3$LO+NNLL accurate predictions for the two-jet rate in the Durham clustering algorithm at $e^+e^-$ collisions, as well as a simultaneous fit of the two- and three-jet rates taking into account correlations between the two observables. The fits are performed on a large range of data sets collected at LEP and PETRA colliders, with energies spanning from $35$ GeV to $207$ GeV. Owing to the high accuracy of the predictions used, the perturbative uncertainty is considerably smaller than that due to hadronization. Our best determination at the $Z$ mass is $α_s(M_Z) = 0.11881 \pm 0.00063(exp.) \pm 0.00101(hadr.) \pm 0.00045(ren.) \pm 0.00034(res.)$, which is in agreement with the latest world average and has a comparable total uncertainty.

hep-ph↗

arXiv2018

Soft-drop event shapes in electron-positron annihilation at next-to-next-to-leading order accuracy

We present predictions for soft-drop event shapes of hadronic final states in electron-positron annihilation at next-to-next-to-leading order accuracy in perturbation theory obtained using the CoLoRFulNNLO subtraction method. We study the impact of the soft drop on the convergence of the perturbative expansion for the distributions of three event shape variables, the soft-drop thrust, the hemisphere jet and narrow jet invariant masses. We find that grooming generally improves perturbative convergence for these event shapes. This better perturbative stability, in conjunction with a reduced sensitivity to non-perturbative hadronization corrections makes soft-drop event shapes promising observables for the precise determination of the strong coupling at lepton colliders.

hep-ph↗

arXiv2018

CoLoRFulNNLO for LHC processes

In my talk I gave a status update on the extension of the CoLoRFulNNLO subtraction method for computing QCD jet cross sections with hadrons in the initial state. The scheme has been fully worked out previously for electron-positron collisions and recently important steps have been made towards generalizing it to be able to deliver corrections of the same order for LHC processes as well. In particular, the important bottleneck of regularizing multiple real emissions has been addressed. We demonstrate the numerical stability of the CoLoRFulNNLO method by computing the doubly real contribution for Higgs-boson production in gluon-gluon fusion and for W production.

hep-ph↗

arXiv2018

Associated production of a Higgs boson decaying into bottom quarks at the LHC in full NNLO QCD

We consider the production of a Standard Model Higgs boson decaying to bottom quarks in association with a vector boson W/Z in hadron collisions. We present a fully exclusive calculation of QCD radiative corrections both for the production cross section and for the Higgs boson decay rate up to next-to-next-to-leading order (NNLO) accuracy. Our calculation also includes the leptonic decay of the vector boson with finite-width effects and spin correlations. We consider typical kinematical cuts applied in the experimental analyses at the Large Hadron Collider (LHC) and we find that the full NNLO QCD corrections significantly decrease the accepted cross section and have a substantial impact on the shape of distributions. We point out that these additional effects are essential to obtain precise theoretical predictions to be compared with the LHC data.

hep-ph↗

arXiv2017

Energy-energy correlation in electron-positron annihilation at NNLL+NNLO accuracy

We present the computation of energy-energy correlation in $e^+e^-$ collisions in the back-to-back region at next-to-next-to-leading logarithmic accuracy matched with the next-to-next-to-leading order perturbative prediction. We study the effect of the fixed higher order corrections in a comparison of our results to LEP and SLC data. The next-to-next-to-leading order correction has a sizable impact on the extracted value of $α_{\mathrm S}(M_Z)$, hence its inclusion is mandatory for a precise measurement of the strong coupling using energy-energy correlation.

hep-ph↗

arXiv2017

Higher order corrections in the CoLoRFulNNLO framework

We discuss the CoLoRFulNNLO method for computing higher order radiative corrections to jet cross sections in perturbative QCD. We apply our method to the calculation of event shapes and jet rates in three-jet production in electron-positron annihilation. We validate our code by comparing our predictions to previous results in the literature and present the jet cone energy fraction distribution at NNLO accuracy. We also present preliminary NNLO results for the three-jet rate using the Durham jet clustering algorithm matched to resummed predictions at NLL accuracy, and a comparison to LEP data.

hep-ph↗

arXiv2016

Jet production in the CoLoRFulNNLO method: event shapes in electron-positron collisions

We present the CoLoRFulNNLO method to compute higher order radiative corrections to jet cross sections in perturbative QCD. We apply our method to the computation of event shape observables in electron-positron collisions at NNLO accuracy and validate our code by comparing our predictions to previous results in the literature. We also calculate for the first time jet cone energy fraction at NNLO.

hep-ph↗

arXiv2016

Three-jet production in electron-positron collisions using the CoLoRFulNNLO method

We introduce a subtraction method for jet cross sections at next-to-next-to-leading order (NNLO) accuracy in the strong coupling and use it to compute event shapes in three-jet production in electron-positron collisions. We validate our method on two event shapes, thrust and C-parameter, which are already known in the literature at NNLO accuracy and compute for the first time oblateness and the energy-energy correlation at the same accuracy.

hep-ph↗

arXiv2010

NNLO jet cross sections by subtraction

We report on the computation of a class of integrals that appear when integrating the so-called iterated singly-unresolved approximate cross section of the NNLO subtraction scheme of [1-4], over the factorised phase space of unresolved partons. The integrated approximate cross section itself can be written as the product of an insertion operator (in colour space) times the Born cross section. We give selected results for the insertion operator for processes with two and three hard partons in the final state.

hep-ph↗

arXiv2008

A subtraction scheme for computing QCD jet cross sections at NNLO: integrating the subtraction terms I

In previous articles we outlined a subtraction scheme for regularizing doubly-real emission and real-virtual emission in next-to-next-to-leading order (NNLO) calculations of jet cross sections in electron-positron annihilation. In order to find the NNLO correction these subtraction terms have to be integrated over the factorized unresolved phase space and combined with the two-loop corrections. In this paper we perform the integration of all one-parton unresolved subtraction terms.

hep-ph↗

arXiv2008

Analytic integration of real-virtual counterterms in NNLO jet cross sections I

We present analytic evaluations of some integrals needed to give explicitly the integrated real-virtual integrated counterterms, based on a recently proposed subtraction scheme for next-to-next-to-leading order (NNLO) jet cross sections. After an algebraic reduction of the integrals, integration-by-parts identities are used for the reduction to master integrals and for the computation of the master integrals themselves by means of differential equations. The results are written in terms of one- and two-dimensional harmonic polylogarithms, once an extension of the standard basis is made. We expect that the techniques described here will be useful in computing other integrals emerging in calculations in perturbative quantum field theories.

hep-ph↗