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We calculate the complete soft-gluon corrections for the production of colorless final states through N³LO 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 N³LO soft-gluon corrections to the total cross section and the charged-Higgs rapidity distribution. This is the first calculation of complete N³LO soft-gluon corrections for a process in single-particle-inclusive kinematics, and the results can be applied to other processes with colorless final states.

We study higher-order QCD corrections for the production of a top–antitop quark pair ($$t{{\bar{t}}}$$$t\overline{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.

We consider$$Z'$$$Z^{\prime }$s in heterotic string derived models and study$$Z'$$$Z^{\prime }$resonant production at the TeV scale at the Large Hadron Collider (LHC). We use various kinematic differential distributions for the Drell–Yan process at NNLO in QCD to explore the parameter space of such models and investigate$$Z'$$$Z^{\prime }$couplings. In particular, we study the impact ofZ-$$Z'$$$Z^{\prime }$kinetic-mixing interactions on forward-backward asymmetry ($$A_{FB}$$$A_{\mathrm{FB}}$) and other distributions at the LHC.

We investigate the impact of sterile neutrinos on the decay rate of extra$$Z'$$$Z^{\prime }$s with mass in the TeV range in heterotic string derived models. We explore the impact of sterile neutrinos on the current$$Z'$$$Z^{\prime }$mass exclusion limits at the LHC, and how these bounds change when the parameter space of this specific class of models is modified.

We study QCD corrections for the associated production of a single top quark and a photon ($$tq\gamma $$$tq\gamma$production) at hadron colliders. We calculate the NLO cross section at LHC and future collider energies for a variety of kinematical cuts, and we estimate uncertainties from scale dependence and from parton distributions. We also calculate differential distributions in top-quark transverse-momentum and rapidity as well as photon energy. Finally, we study higher-order corrections from soft-gluon emission for this process, and we provide approximate NNLO (aNNLO) results for the cross section and top-quark differential distributions. We also compare our calculations with recent measurements from CMS and ATLAS at the LHC and find that the aNNLO corrections improve the comparison between the data and the Standard Model predictions.