arXiv subjects

Marco Vitti

Publications and source records attributed to Marco Vitti.

13 recordsLinked to original sources

arXiv2026

Higgs Boson Pair Production via Gluon Fusion: Higher-Order Corrections and Theoretical Uncertainties

In this contribution, the higher-order QCD and electroweak corrections to Standard Model Higgs boson pair production via the gluon-fusion mechanism, $gg\to hh$, are summarized and the different sources of theoretical uncertainty are assessed. The discussion includes finite top quark mass effects, matching to parton showers, approximate NNLO and N$^3$LO QCD corrections, NLO electroweak effects, and uncertainties associated with the top quark mass scheme and perturbative scale choices. In addition, we provide an updated state-of-the-art recommendation for the inclusive gluon-fusion Higgs boson pair production cross section and the corresponding Higgs boson pair invariant-mass distribution.

hep-ph↗

arXiv2026

Infra-red enhanced loops in quadratic gravity

It has been suggested that logarithmically enhanced infra-red loop corrections arising in theories with four derivatives correspond to a physical running of couplings, rendering quadratic gravity asymptotically free. We find that these effects depend on the gauge and on the field parameterisation. We compute physical on-shell amplitudes and find genuine infra-red log-enhanced loop corrections, that are process-dependent and cannot be absorbed into running couplings. As a byproduct, we derive the effective action of quadratic gravity at tree level, showing that its ghost does not contribute to effective operators and thereby does not violate positivity bounds.

hep-th↗

arXiv2025

$gg \to ZH$ : updated predictions at NLO QCD

We present state-of-the-art predictions for the inclusive cross section of gluon-initiated $ZH$ production, following the recommendations of the LHC Higgs Working Group. In particular, we include NLO QCD corrections, where the virtual corrections are obtained from the combination of a forward expansion and a high-energy expansion, and the real corrections are exact. The expanded results for the virtual corrections are compared in detail to full numerical results. The updated predictions show a reduction of the scale uncertainties to the level of 15%, and they include an estimate of the top-mass-scheme uncertainty.

hep-ph↗

arXiv2025

Two-loop QCD corrections to $ZH$ and off-shell $Z$ boson pair production in gluon fusion

We compute two-loop corrections to the associated production of a Higgs boson with a $Z$ boson and to off-shell $Z$ boson pair production in the gluon fusion channel, mediated by a heavy quark. We perform deep expansions in the high-energy region and around the forward limit and show that their combination covers the whole phase space. Our results constitute the next-to-leading order virtual corrections to these processes. Their numerical evaluation is fast and the dependence on all parameters is maintained, thus a change of parameter values or renormalization scheme is straightforward. As a by-product of our calculation, we also obtain the two-loop heavy quark mediated virtual corrections to the processes of off-shell di-photon and photon-$Z$ production.

hep-ph↗

arXiv2025

Constraining four-heavy-quark operators with top-quark, Higgs, and electroweak precision data

We establish constraints on the dimension-six four-heavy-quark operators in the Standard Model Effective Field Theory (SMEFT) by synthesising LHC measurements of top-quark and single-Higgs production with electroweak precision observables. We scrutinise the choice of the $\gamma_5$ scheme in single-Higgs calculations, demonstrating its non-negligible impact on SMEFT fits.

hep-ph↗

arXiv2024

Subleading operators and gamma5-scheme dependence in SMEFT for Higgs boson pair production

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.

hep-ph↗

arXiv2024

Three-loop corrections to Higgs boson pair production: reducible contribution

We compute three-loop corrections to the process $gg\to HH$ originating from one-particle reducible diagrams. This requires the computation of two-loop corrections to the gluon-gluon-Higgs vertex with an off-shell gluon. We describe in detail our approach to obtain semi-analytic results for the vertex form factors and present results for the two form factors contributing to Higgs boson pair production.

hep-ph↗

arXiv2024

Virtual QCD corrections to $gg \to ZZ$: top-quark loops from a transverse-momentum expansion

We present the virtual corrections due to the top-quark loops for the process $gg \to ZZ$ at next-to-leading order in QCD. The associated two-loop box diagrams are computed using a small-transverse-momentum expansion. Our results are then merged with those available in the complementary energy region, obtained via a high-energy expansion, in order to provide an analytic result that is valid in the whole phase space. The results presented allow for an efficient modelling of the signal--background interference as well as the irreducible background in off-shell Higgs production.

hep-ph↗

arXiv2024

On $γ_5$ schemes and the interplay of SMEFT operators in the Higgs-gluon coupling

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.

hep-ph↗

arXiv2023

Light-quark Yukawa couplings from off-shell Higgs production

Yukawa couplings of the first quark generation are notoriously difficult to constrain due to their small values within the Standard Model. Here we propose Higgs off-shell production, with the Higgs boson decaying to four leptons, as a probe of the up- and down-quark Yukawa couplings. Using kinematic discriminants similar to the ones employed in the Higgs width measurements we find that the down (up) Yukawa coupling can be constrained to a factor of 156 (260) times its Standard Model value at the high-luminosity LHC assuming only experimental systematic uncertainties. Off-shell Higgs production hence provides better sensitivity to the first-generation quark Yukawa couplings with respect to other probes such as Higgs+jet or Higgs pair production.

hep-ph↗

arXiv2022

On the NLO QCD Corrections to Gluon-Initiated ZH Production

We compute the QCD corrections at next-to-leading order for the process $gg \rightarrow ZH$, including both the virtual two-loop terms and real-emission contributions. The two-loop box diagrams in the virtual corrections are approximated analytically over the complete phase space, combining the results of an expansion in the limit of small transverse momentum and an expansion in the regime of high energy. We obtain both inclusive and differential results for the cross section. We find that the NLO QCD corrections are of the same size as the LO contribution up to $ZH$ invariant masses close to 1 TeV, but they increase significantly when higher energies are considered, due to a class of real-emission diagrams in which the $Z$ boson is radiated from an open quark line. Finally, we estimate the uncertainty due to the renormalization scheme used for the top-quark mass both on the total and differential cross section.

hep-ph↗

arXiv2022

Gluon Fusion Production at NLO: Merging the Transverse Momentum and the High-Energy Expansions

The virtual corrections to $gg\to HH$ and $gg\to ZH$ are analytically evaluated combining an expansion in the small transverse momentum of the final particles with an expansion valid at high energies. The two expansion methods describe complementary regions of the phase space and we merge their results, extending the range of validity of both expansions using Padé approximants. We show that this approach can reproduce the available numerical results retaining the exact top quark mass dependence with an accuracy well below the 1% level. Our results allow a fast and flexible evaluation of the virtual corrections of the considered processes. Furthermore, they are available in different renormalisation schemes of the top quark mass.

hep-ph↗

arXiv2021

Virtual corrections to $gg\to ZH$ via a transverse momentum expansion

We compute the next-to-leading virtual QCD corrections to the partonic cross section of the production of a Higgs boson in association with a $Z$ boson in gluon fusion. The calculation is based on the recently introduced method of evaluating the amplitude via an expansion in terms of a small transverse momentum. We generalize the method to the case of different masses in the final state and of a process not symmetric in the forward-backward direction exchange. Our analytic approach gives a very good approximation (better than percent) of the partonic cross section in the center of mass energy region up to $\sim 750 \,\textrm{GeV}$, where at the LHC $\sim 98\%$ of the total hadronic cross section is concentrated.

hep-ph↗