arXiv subjects

Nikolaos Kidonakis

Publications and source records attributed to Nikolaos Kidonakis.

At least 19 recordsLinked to original sources

arXiv2026

N$^3$LO soft-gluon corrections for $Z\gamma$ production

We calculate soft-gluon corrections for $Z\gamma$ production through next-to-next-to-next-to-leading-order (N$^3$LO) in one-particle-inclusive (1PI) kinematics. We use these results to produce approximate N$^3$LO (aN$^3$LO) QCD predictions for $Z\gamma$ production cross sections in proton-proton collisions at LHC energies. Differential cross sections in photon transverse momentum $p_T^\gamma$ and rapidity $y^\gamma$ are computed at 13 TeV and 13.6 TeV collider energies. Higher-order $K$-factors are examined systematically, and scale and PDF uncertainties are quantified at each perturbative order. Soft-gluon corrections are found to be significant in the high-$p_T$ region, with good perturbative convergence observed at aN$^3$LO.

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arXiv2026

$t\bar t$ production as a probe of dimension-6 SMEFT at higher orders

We study top-antitop pair production in proton-proton collisions within the Standard Model Effective Field Theory (SMEFT) at dimension 6. We focus on the top chromomagnetic operator $C_{tG}$ together with the four-quark operators relevant for unpolarized $t{\bar t}$ production. We analyze the top-quark single-differential transverse-momentum ($p_T$) and rapidity ($y$) distributions and the double-differential distributions in $p_T$ and $y$ ($p_T\times y$) at 13~TeV, and we present projections for 13.6~TeV using the same binning. Our highest-order setup combines next-to-next-to-leading-order (NNLO) Standard Model (SM) predictions with approximate NNLO (aNNLO) SM--SMEFT interference corrections. We find that higher-order QCD effects are essential for a stable SMEFT interpretation, yielding substantially more robust bounds and milder parameter degeneracies. The strongest sensitivity is obtained for $C_{tG}$. In the combined highest-order analysis of the 13-TeV results and 13.6-TeV projections, we obtain sensitivity to effective scales up to 3.9~TeV. Our results show that higher-order differential top-pair production provides a precise and theoretically controlled probe of the top chromomagnetic interaction.

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arXiv2026

Constraining dimension-6 SMEFT with higher-order predictions for $p p \to t W$

We study single-top production in association with a $W$ boson at the Large Hadron Collider (LHC) as a probe of dimension-6 Standard Model effective field theory (SMEFT) at leading order, next-to-leading order, and approximate next-to-next-to-leading order accuracy in quantum chromodynamics (QCD). The process is sensitive to operators that modify the top-quark weak and chromomagnetic dipole interactions, and we perform three-parameter linear and quadratic SMEFT fits using doubly differential top-quark distributions in transverse momentum and rapidity for the Run II and Run III configurations at the LHC. We provide a detailed account of the uncertainties and quantify the impact of the different uncertainty components across bins and perturbative orders. We find that effective scales up to 2 TeV can be probed in nonmarginalized fits, while in marginalized fits the corresponding scales are around 0.5 and 1.5 TeV for linear and quadratic fits, respectively.

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arXiv2025

Top-quark production cross sections at higher perturbative orders

I present calculations of higher-order corrections to top-quark production via three different processes: the production of a top-antitop pair and a $Z$ boson; single-top quark production in the $s$-channel; and top-antitop production with a Higgs boson. It is shown that the contributions from soft-gluon corrections are numerically dominant and large in all these processes. I present approximate NNLO (aNNLO) and approximate N$^3$LO (aN$^3$LO) cross sections that include soft-gluon corrections added to the exact NLO QCD results. Electroweak corrections through NLO are also included for $t{\bar t}Z$ and $t{\bar t}H$ production. The theoretical predictions are compared to LHC measurements of total cross sections for these processes.

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arXiv2025

Higher-order corrections for $t{\bar t}Z$ production

We present calculations of higher-order QCD and electroweak (EW) corrections to the associated production of a top-antitop quark pair and a $Z$ boson, i.e. $t{\bar t}Z$ production, in proton collisions. We find that the contributions from soft-gluon corrections are numerically dominant and large. We present approximate NNLO (aNNLO) and approximate N$^3$LO (aN$^3$LO) cross sections that include soft corrections on top of the exact NLO QCD result. We also add electroweak corrections through NLO. We compare our aN$^3$LO QCD + NLO EW theoretical results to measurements of total cross sections from the LHC, and we also calculate top-quark differential distributions in transverse momentum and rapidity.

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arXiv2025

Higher-order QCD and electroweak corrections for $t{\bar t}H$ production

We calculate higher-order soft-gluon corrections for the associated production of a top-antitop quark pair and a Higgs boson ($t{\bar t}H$ production) using resummation in one-particle-inclusive (1PI) kinematics. By adding these corrections to NLO QCD and NLO electroweak (EW) results, we present cross sections through approximate N$^3$LO (aN$^3$LO) in QCD and NLO in EW for $t{\bar t}H$ production at LHC energies. These aN$^3$LO QCD + NLO EW results provide significant enhancements over lower orders and a reduced scale dependence. Based on our results and current experimental data, we derive a constraint on the deviation of the top quark Yukawa coupling from the Standard Model value which is a probe of new physics beyond it. We also calculate top-quark differential distributions in transverse momentum and rapidity.

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arXiv2025

Higher-order soft and virtual corrections in $p p \to \gamma W$ production at the LHC

We study higher-order QCD corrections beyond NLO for the associated production of a photon with a $W$ boson ($\gamma W^+$ and $\gamma W^-$ production) at the Large Hadron Collider. We calculate the NNLO soft-plus-virtual QCD corrections as well as the N$^3$LO soft-gluon corrections to the total production cross section and the photon transverse-momentum distribution in single-particle-inclusive kinematics. The higher-order corrections provide a significant enhancement to the cross section. This is the first calculation of the complete soft-gluon corrections at N$^3$LO in single-particle-inclusive kinematics for a Standard Model process.

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arXiv2025

Resummation for $s$-channel single-top production

I present higher-order results for $s$-channel single-top-quark production that are derived from soft-gluon resummation. I show that the soft-gluon corrections provide the dominant contribution to the QCD corrections, and that they approximate very well the exact results through NNLO. Furthermore, approximate N$^3$LO corrections are computed by using the expansion of the resummed cross section to third order in the strong coupling. The calculation treats the final-state $b$-quarks as massless but I also show how to extend the formalism to the case of massive $b$-quarks. The higher-order corrections are large at LHC energies and they improve the theoretical accuracy.

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arXiv2024

Progress in top-quark pair production cross section calculations and impact on parton distribution functions of the proton

We discuss the impact of eligible top-quark pair production differential cross-section measurements at the LHC with a collision energy of 13 TeV on the parton distribution functions (PDFs) of the proton as well as the impact of approximate next-to-next-to-next-to-leading order (aN$^3$LO) QCD corrections combined with next-to-leading order (NLO) electroweak (EW) corrections on $t\bar t$ observables. We illustrate the effects on the gluon PDF at large $x$ from an optimal baseline selection of data in NNLO global fits, and show comparisons between the theory prediction for $t\bar t$ total and differential cross sections at aN$^3$LO QCD combined with NLO EW and recent measurements from the ATLAS and CMS collaborations at the LHC.

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arXiv2024

Higher-order soft-gluon corrections for $t{\bar t}Z$ cross sections

We calculate higher-order soft-gluon corrections for the associated production of a top-antitop quark pair and a $Z$ boson ($t{\bar t}Z$ production) in proton-proton collisions. We find that these corrections are numerically dominant and large. We present approximate NNLO (aNNLO) and approximate N$^3$LO (aN$^3$LO) cross sections that add, respectively, second-order and third-order soft-gluon corrections to the exact NLO QCD result. We also add electroweak (EW) corrections through NLO. We estimate uncertainties that arise from scale dependence, which are smaller at higher orders, and from parton distribution functions. We compare our aN$^3$LO QCD + NLO EW theoretical results to measurements of $t{\bar t}Z$ cross sections from the LHC and find good agreement. We also calculate single-particle-inclusive differential distributions in top-quark transverse momentum and rapidity.

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arXiv2024

Higher-order corrections to top-quark pair production in the SMEFT

We present theoretical results at approximate NNLO in QCD for top-quark pair-production total cross sections and top-quark differential distributions at the LHC in the SMEFT. In this work we consider effects of new physics parametrized by the chromomagnetic dipole operator. These approximate results are obtained by adding higher-order soft gluon corrections to the complete NLO calculations. The higher-order corrections are large, and they reduce the scale uncertainties. These improved theoretical predictions can be used to set stronger bounds on top-quark QCD anomalous couplings.

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arXiv2024

Theoretical results for top-pair and top+$W$ production

I present theoretical results for top-pair production as well as for the associated production of top quarks with $W$ bosons. Soft-gluon corrections from resummation are calculated through approximate N$^3$LO and added to fixed-order QCD results, and electroweak corrections are included at NLO. Top-quark transverse-momentum and rapidity distributions are also presented. In all cases the higher-order corrections are large, they reduce the scale dependence, and they improve agreement with recent data.

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arXiv2024

Theoretical predictions for $t{\bar t}W$ cross sections at approximate N$^3$LO

We present theoretical calculations of higher-order QCD and electroweak corrections for the associated production of a top-antitop quark pair and a $W$ boson ($t{\bar t}W$ production) at LHC energies. We show predictions for cross sections at approximate N$^3$LO (aN$^3$LO) which include second-order and third-order soft-gluon corrections added to the exact NLO QCD+electroweak result. We compare our results to recent measurements from the LHC, and we find that our predictions provide improved agreement with the data. We also calculate the top-quark transverse momentum and rapidity distributions in $t{\bar t}W$ production. We find significant enhancements from the higher-order corrections to the total and differential cross sections for this process.

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arXiv2024

SMEFT chromomagnetic dipole operator contributions to $t{\bar t}$ production at approximate NNLO in QCD

We study higher-order QCD corrections for the production of a top-antitop quark pair ($t{\bar t}$ production) at the Large Hadron Collider in the Standard Model Effective Field Theory. We consider effects of new physics parametrized by the top-quark chromomagnetic dipole operator. We calculate new physics contributions to the total cross section at approximate NNLO, with second-order soft-gluon corrections added to the complete NLO result, including uncertainties from scale dependence and from parton distributions. We also calculate new physics contributions at approximate NNLO for differential distributions in top-quark transverse momentum.

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arXiv2024

Soft-gluon corrections in $t{\bar t}W$ production

We study higher-order QCD corrections for the associated production of a top-antitop quark pair and a $W$ boson ($t{\bar t}W$ production) in proton-proton collisions. We calculate approximate NNLO (aNNLO) and approximate N$^3$LO (aN$^3$LO) cross sections, with second-order and third-order soft-gluon corrections added to the exact NLO QCD result, and we also include electroweak (EW) corrections through NLO. We calculate uncertainties from scale dependence, which are reduced at higher orders, and from parton distributions, and we also provide separate results for $t{\bar t}W^+$ and $t{\bar t}W^-$ production. We compare our results to recent measurements from the LHC, and we find that the aN$^3$LO QCD + NLO EW predictions provide improved agreement with the data. We also calculate differential distributions in top-quark transverse momentum and rapidity and find significant enhancements from the higher-order corrections. This is the first calculation of soft-gluon corrections in single-particle-inclusive kinematics for a $2 \to 3$ process where all final-state particles are massive.

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arXiv2024

N$^3$LO soft-gluon corrections in single-particle-inclusive kinematics and $H^+ H^-$ production

We calculate the complete soft-gluon corrections for the production of colorless final states through N$^3$LO in single-particle-inclusive kinematics. We present explicit analytical results and use them to study higher-order QCD corrections for the production of a heavy charged Higgs pair ($H^+ H^-$) via quark-antiquark annihilation in the Two-Higgs-Doublet Model at LHC energies. We calculate the NNLO soft-gluon and virtual QCD corrections as well as the N$^3$LO soft-gluon corrections to the total cross section and the charged-Higgs rapidity distribution. This is the first calculation of complete N$^3$LO soft-gluon corrections for a process in single-particle-inclusive kinematics, and the results can be applied to other processes with colorless final states.

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arXiv2023

Top-quark cross sections and distributions at aN$^3$LO

We present theoretical predictions for top-quark total cross sections and for differential distributions in top-quark transverse momentum and rapidity. Third-order soft gluon corrections are added to the complete NNLO quantities to provide approximate N$^3$LO (aN$^3$LO) results, and electroweak corrections at NLO are also included. We calculate the theoretical uncertainties from scale dependence and from parton distribution functions in the proton, and estimate their impact on the total and differential cross sections. The higher-order corrections are large and they reduce the scale uncertainties. The results presented in this work include the best current theoretical input and are in good agreement with recent data from the LHC.

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arXiv2023

aNNLO results for $t{\bar t}γ$ cross sections

We present theoretical calculations of total cross sections and top-quark transverse-momentum and rapidity distributions in the associated production of a top-antitop pair with a photon ($t{\bar t}γ$ production). We include complete QCD and electroweak corrections at NLO as well as soft-gluon corrections at approximate NNLO (aNNLO). The aNNLO corrections are very significant, they decrease theoretical uncertainties, and they are needed for better comparison with data from the LHC.

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