arXiv subjects

Simone Devoto

Publications and source records attributed to Simone Devoto.

At least 19 recordsLinked to original sources

arXiv2026

Towards the two-loop electroweak corrections to the Drell-Yan process: the complete fermionic contributions

We discuss the production of a lepton pair in quark-antiquark annihilation in the electroweak Standard Model. We present the ultraviolet-renormalised and infrared-subtracted finite contribution of the complete set of second-order virtual corrections with a closed fermionic loop, to the cross section of the process $u\bar u\to \mu^+\mu^-$. The evaluation of these contributions is based on an automated methodology, whose validity is discussed with explicit tests. These corrections are one of the building blocks necessary for the simulation of the inclusive lepton-pair production cross section at next-to-next-to-leading order in the electroweak interaction.

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arXiv2025

Towards the two-loop electroweak corrections to the Drell-Yan process: the infrared structure

We discuss the lepton-pair production process in Quantum Electrodynamics. We present the ultraviolet-renormalised and infrared-subtracted finite contribution of the second-order virtual corrections to the inclusive lepton-pair production cross section $u\bar u\to e^+e^-$. The results are obtained within a new computational framework, OCEANN, developed in view of the evaluation of the exact two-loop electroweak virtual corrections to high-energy scattering processes. One of the key methodological features in this approach is the representation of the scattering amplitude with arbitrary precision at every stage of the calculation. The analysis in QED allows us to address the treatment of the infrared structure of the process and it can be easily extended to the complete electroweak Standard Model case. The perfect agreement with the literature, for this subset of corrections, provides a non trivial validation of the general framework.

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arXiv2025

Soft contributions to heavy quark production in arbitrary kinematics

We present the computation of the soft-parton contribution at low transverse momentum for the production of a heavy quark pair in association with a colour singlet at the next-to-next-to-leading order (NNLO) in the QCD coupling. This paper extends to arbitrary kinematics previous results obtained under the assumption of a back-to-back configuration for the final-state emitters. These new results take into account the production of an additional colour singlet system, thus allowing for the evaluation of the resummation formula for associated heavy-quark pair production at NNLO, and the implementation of the qT subtraction formalism for this class of processes. We provide the results in the form of a code for their on-the-fly evaluation.

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arXiv2025

State-of-the-art cross sections for ttH: NNLO predictions matched with NNLL resummation and EW corrections

We present new, state-of-the-art predictions for the associated production of the SM Higgs boson with top quarks, computed in accordance with the recommendations of the LHC Higgs Working Group. The NNLO QCD predictions, derived through suitable approximations of the two-loop virtual contribution, are supplemented with soft-gluon resummation up to NNLL accuracy. Two distinct resummation frameworks are employed - one based on direct QCD and the other on soft-collinear effective theory - and their features are compared in detail. These results are further combined with the complete-NLO corrections, yielding the most precise SM predictions for this process to date. The relevant sources of theoretical uncertainties are thoroughly estimated and discussed.

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arXiv2024

Mixed QCD-EW corrections to the neutral-current Drell-Yan process

We report on the complete computation of the mixed QCD-electroweak corrections to the neutral-current Drell-Yan process. Our calculation holds in the entire range of dilepton invariant masses. We present phenomenological results for several kinematical distributions in the case of bare muons both in the resonant region and for high invariant masses. We also consider the forward-backward asymmetry, which is a key observable to measure the weak mixing angle. We finally extend our calculation to dressed leptons and compare our results in the massless limit to those available in the literature.

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arXiv2024

Precise predictions for $t \bar t H$ production at the LHC: inclusive cross section and differential distributions

We present the first fully differential next-to-next-to-leading order (NNLO) QCD calculation for the production of a top-antitop quark pair in association with a Higgs boson ($t \bar t H$) at hadron colliders. The computation is exact, except for the finite part of the two-loop virtual contribution, which we estimate using two different methods that yield consistent results within their respective uncertainties. The first method relies on a soft-Higgs factorisation formula that we develop up to the three-loop order. The second is based on a high-energy expansion in the small top-mass limit. Combining the newly computed corrections with the complete set of next-to-leading order (NLO) QCD+EW results provides the most advanced perturbative prediction currently available at the LHC for both inclusive and differential $t \bar t H$ cross sections. The uncertainties due to the missing exact two-loop contribution are conservatively estimated to be at the percent level, both for the total cross section and for most of the differential distributions, and therefore subleading compared to the residual perturbative uncertainties.

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arXiv2024

Two-loop mixed QCD-EW corrections to charged current Drell-Yan

We present the two-loop mixed strong-electroweak virtual corrections to the charged current Drell-Yan process. The final-state collinear singularities are regularised by the lepton mass. The evaluation of all the relevant Feynman integrals, including those with up to two different internal massive lines, has been worked out relying on semi-analytical techniques, using complex-valued masses. We can provide, at any arbitrary phase-space point, the solution as a power series in the $W$-boson mass, around a reference value. Starting from these expansions, we can prepare a numerical grid for any value of the $W$-boson mass within their radius of convergence in a negligible amount of time.

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arXiv2023

$t\bar tH$ production in NNLO QCD

In this contribution we present our recent computation of the NNLO QCD corrections to the production of a Higgs boson associated with a top-antitop quark pair. This process is of great importance since it allows for a direct measurement of the top-quark Yukawa coupling, and the inclusion of NNLO corrections is crucial in order to provide theory predictions with an uncertainty competitive with the projected accuracy of the experimental measurements at the end of the high-luminosity phase of the LHC.

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arXiv2023

Soft-gluon effective coupling: perturbative results and the large-nF limit to all orders

We consider extensions of the soft-gluon effective coupling that generalize the Catani--Marchesini--Webber (CMW) coupling in the context of soft-gluon resummation beyond the next-to-leading logarithmic accuracy. Starting from the probability density of correlated soft emission in d dimensions we introduce a class of soft couplings relevant for resummed QCD calculations of hard-scattering observables. We show that at the conformal point, where the d-dimensional QCD $\beta$ function vanishes, all these effective couplings are equal and they are also equal to the cusp anomalous dimension. We present explicit results in d dimensions for the soft-emission probability density and the soft couplings at the second-order in the QCD coupling $\alpha_s$. In d=4 dimensions we obtain the explicit relation between the soft couplings at ${\cal O}(\alpha_s^3).$ Finally, we study the structure of the soft coupling in the large-$n_F$ limit and we present explicit expressions to all orders in perturbation theory. We also check that, at the conformal point, our large-$n_F$ results agree with the known result of the cusp anomalous dimension.

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arXiv2023

Precise predictions for the associated production of a $W$ boson with a top-antitop quark pair at the LHC

The production of a top-antitop quark pair in association with a $W$ boson ($t\bar tW$) is one of the heaviest signatures currently probed at the Large Hadron Collider (LHC). Since the first observation reported in 2015 the corresponding rates have been found to be consistently higher than the Standard Model predictions, which are based on next-to-leading order~(NLO) calculations in the QCD and electroweak (EW) interactions. We present the first next-to-next-to-leading order (NNLO) QCD computation of $t\bar tW$ production at hadron colliders. The calculation is exact, except for the finite part of the two-loop virtual corrections, which is estimated using two different approaches that lead to consistent results within their uncertainties. We combine the newly computed NNLO QCD corrections with the complete NLO QCD+EW results, thus obtaining the most advanced perturbative prediction available to date for the \ttW inclusive cross section. The tension with the latest ATLAS and CMS results remains at the $1\sigma-2\sigma$ level.

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arXiv2023

Soft-parton contributions to heavy-quark production at low transverse momentum

We consider QCD radiative corrections to the production of a heavy-quark pair in hadronic collisions. We present the computation of the soft-parton contributions at low transverse momentum of the heavy-quark pair up to second order in the QCD coupling $\alpha_s$. These results complete the evaluation at the next-to-next-to-leading order (NNLO) of the transverse-momentum resummation formula for this process. Moreover, they give all the ingredients that are needed for the NNLO implementation of the qT subtraction formalism for heavy-quark production. We discuss the details of the computation and we provide a code that can be used to obtain the relevant results in numerical form.

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arXiv2022

Associated production of a $W$ boson and massive bottom quarks at next-to-next-to-leading order in QCD

We present the first calculation for the hadroproduction of a $W$ boson in association with a massive bottom ($b$) quark-antiquark pair at next-to-next-to-leading order (NNLO) in QCD perturbation theory. We exploit the hierarchy between the $b$ quark mass and the characteristic energy scale of the process to obtain a reliable analytic expression for the two-loop virtual amplitude with three massive legs, starting from the corresponding result available for massless bottom quarks. The use of massive $b$ quarks avoids the ambiguities associated with the correct flavour assignment in massless calculations, paving the way to a more realistic comparison with experimental data. We present phenomenological results considering proton-proton collisions at centre-of-mass energy $\sqrt{s}=13.6$ TeV for inclusive $Wb \bar b$ production and within a fiducial region relevant for the associated production of a $W$ boson and a Higgs boson decaying into a $b \bar b$ pair, for which $Wb \bar b$ production represents one of the most relevant backgrounds. We find that the NNLO corrections are substantial and that their inclusion is mandatory to obtain reliable predictions.

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arXiv2022

Higgs boson production in association with a top-antitop quark pair in next-to-next-to leading order QCD

The associated production of a Higgs boson with a top-antitop quark pair is a crucial process at the LHC since it allows for a direct measurement of the top-quark Yukawa coupling. We present the computation of the radiative corrections to this process at the next-to-next-to-leading order (NNLO) in QCD perturbation theory. This is the very first computation for a $2 \to 3$ process with massive coloured particles at this perturbative order. We develop a soft Higgs boson approximation for loop amplitudes, which enables us to reliably quantify the impact of the yet unknown two-loop contribution. At the centre-of-mass energy $\sqrt{s}=13$ TeV the NNLO corrections increase the next-to-leading order result for the total cross section by about 4% and lead to a significant reduction of perturbative uncertainties.

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arXiv2022

Two-loop mixed QCD-EW corrections to neutral current Drell-Yan

We present the mixed QCD-EW two-loop virtual amplitudes for the neutral current Drell-Yan production, one of the bottlenecks for the complete calculation of the NNLO mixed QCD-EW corrections. We present the computational details and the first steps towards their automation. We describe the evaluation of all the relevant two-loop Feynman integrals using analytical and semi-analytical methods, the subtraction of the universal infrared singularities and present the numerical evaluation of the finite remainder.

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arXiv2022

Heavy-quark production at NNLO

We present the calculation of QCD radiative corrections to heavy-quark production at NNLO. The calculation is implemented in an updated version of \textsc{Matrix}, which allows us to obtain multidifferential predictions for stable top quarks. We also report on the NNLO calculation for $b{\bar b}$ production and comment on the inclusion of top-quark decays and of the extension of our results to $t\bar tH$.

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arXiv2022

Evaluation of Feynman integrals with arbitrary complex masses via series expansions

We present an algorithm to evaluate multiloop Feynman integrals with an arbitrary number of internal massive lines, with the masses being in general complex-valued, and its implementation in the \textsc{Mathematica} package \textsc{SeaSyde}. The implementation solves by series expansions the system of differential equations satisfied by the Master Integrals. At variance with respect to other existing codes, the analytical continuation of the solution is performed in the complex plane associated to each kinematical invariant. We present the results of the evaluation of the Master Integrals relevant for the NNLO QCD-EW corrections to the neutral-current Drell-Yan processes.

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arXiv2022

False vacuum decay: an introductory review

We review the description of tunnelling phenomena in the semi-classical approximation in ordinary quantum mechanics and in quantum field theory. In particular, we describe in detail the calculation, up to the first quantum corrections, of the decay probability per unit time of a metastable ground state. We apply the relevant formalism to the case of the standard model of electroweak interactions, whose ground state is metastable for sufficiently large values of the top quark mass. Finally, we discuss the impact of gravitational interactions on the calculation of the tunnelling rate.

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arXiv2022

Two-loop mixed QCD-EW corrections to neutral current Drell-Yan

We present the two-loop mixed strong-electroweak virtual corrections to the neutral current Drell-Yan process and we provide, in ancillary files, the explicit formulae of the infrared-subtracted finite remainder. The final state collinear singularities are regularised by the lepton mass. The evaluation of all the relevant Feynman integrals, including those with up to two internal massive lines, has been worked out relying on analytical and semi-analytical techniques, in the case of complex-valued masses.

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