Measurements of the inclusive and differential cross-sections for top-quark pair and single top production cross sections in proton-proton collisions with the ATLAS detector at the Large Hadron Collider are presented at center-of-mass energies of 8 TeV and 13 TeV. The inclusive measurements reach high precision and are compared to the best available theoretical calculations. These...
Measurements of the inclusive and differential top quark pair production cross section in proton-proton collisions at 5.02 TeV, 7 TeV, 8 TeV and 13 TeV are presented using the CMS detector. The total cross section is measured using the lepton+jets, dilepton and fully hadronic channels, including the tau-dilepton and tau+jets modes. Indirect constraints on both the top quark mass and ɑS are...
Current predictions for the total top-quark pair production cross section are based on NNLO QCD corrections with NNLL soft-gluon resummation. I will discuss the perspectives to go beyond this approximation by using known ingredients for N3LL soft-gluon resummation and Coulomb corrections.
Several measurements of single top quark production in proton-proton collisions at the LHC at centre-of-mass energies of 7, 8 and 13 TeV, using data collected with the CMS experiment, are presented. The analyses investigate separately the productions of top via t-channel exchange, in association with a W boson (tW) or via the s-channel. Final states with at least one charged lepton and one...
Measurements of the top quark mass and width using proton-proton collisions at the LHC at centre-of-mass energies of 7, 8 and 13 TeV are presented. The analyses used different decay channels and production modes of the top quark. Several techniques are investigated based on the reconstruction of the top kinematics from final state products, using leptonic decays with a J/psi, the shapes of top...
We present a NLO QCD calculation of ttj production at the LHC in the dilepton channel, where
all non-resonant diagrams, interferences and off-shell effects of the top quark are included. We investigate different choice of dynamical scales in order to stabilize the perturbative convergence of the differential distributions
far away from the threshold. We will also discuss the application of...
I will discuss the theoretical uncertainties on the top-quark mass
determination, due to bottom-quark fragmentation in top decays.
In particular, the fragmentation parameters in both HERWIG and PYTHIA, the two main parton shower generators, will be taken into account and their impact on several
observables, relevant form the top-mass extraction, will be investigated.
Furthermore, I will also...
We report on our recent progress on the calculation of massive operator matrix elements (OMEs), which at three loop level receive contributions from Feynman diagrams containing two heavy quark lines of different masses. These OMEs are needed in order to obtain the corresponding contributions for the massive Wilson coefficients in deep inelastic scattering at large momentum transfer. They are...
I am going to present some recent results on the resummation of soft gluon emission corrections to the production of a top-antitop pair in association with a Higgs/W/Z boson at the Large Hadron Collider.
First I will introduce and describe the derivation of the soft-gluon resummation formula for these processes. Based on this formula, we developed a dedicated parton-level Monte Carlo program....
The measurement of the associated production of a Higgs boson with a pair of top quarks is among the highest priorities of the current LHC physics program. In this talk latest results for threshold resummation of soft gluon corrections for the $pp \to t\bar{t}H$ process will be presented. The resummation is carried out at next-to-next-to-leading-logarithmic accuracy using the direct QCD Mellin...
State-of-the-art theoretical predictions accurate to next-to-leading order QCD interfaced with Pythia8 and Herwig++ event generators are tested by comparing the unfolded ttbar differential data collected with the CMS detector at 8 and 13 TeV. These predictions are also compared with the underlying event activity distributions in ttbar events using CMS proton-proton data collected at a center...
In this talk, the combination of the one-loop matrix-element generator Recola with the multipurpose Monte Carlo program Sherpa is presented. Since both programs are highly automated, the resulting Sherpa+Recola framework allows for the computation of—in principle—any Standard Model process at both NLO QCD and EW accuracy. The reliability of the Sherpa+Recola framework will be demonstrated via...
Several measurements of top quark properties are presented using data collected by the CMS experiment at different centre-of-mass-energies. The properties are mostly probed in production of the top quarks. The charge asymmetry is measured inclusively and differentially probing anomalous couplings to the gluons at production mode. These measurements are extended searching for asymmetries in...
A comprehensive set of measurements of top quark pair production in association with EWK bosons (W, Z or ɣ) is presented at different centre-of-mass energies. The results are compared to the theory predictions and re-interpreted as searches for new physics inducing deviations from the standard model predictions using an effective field theory approach. The status of the search for double-ttbar...
Searches for new resonances that decay either to pairs of top quarks or a top and a b-quark will be presented. The searches are performed with the ATLAS experiment at the LHC using proton-proton collision data collected in 2015 and 2016 with a centre-of-mass energy of 13 TeV. The invariant mass spectrum of hypothetical resonances are examined for local excesses or deficits that are...
We estimate the top-quark mass extraction uncertainty due to Monte Carlo modeling of top-pair production and its leptonic decay. Using three different NLO+PS generators based on the POWHEG method implementing an increasingly precise treatment of t?t production and decay, including hvq and bb4l, and two different PS implementations we obtain predictions for various kinematic distributions...
