ATLAS reports an 8+ sigma excess in ttbar production near threshold, consistent with NRQCD quasi-bound states and measuring 9.3 pb.
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Percent level precision physics at the Tevatron: first genuine NNLO QCD corrections to q qbar -> t tbar + X
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abstract
We compute the Next-to-Next-to-Leading Order (NNLO) QCD corrections to the partonic reaction that dominates top-pair production at the Tevatron. This is the first ever NNLO calculation of an observable with more than two colored partons, and/or massive fermions, at hadron colliders. Augmenting our fixed order calculation with soft-gluon resummation through Next-to-Next-to-Leading Logarithmic (NNLL) accuracy, we observe that the predicted total inclusive cross-section exhibits a very small perturbative uncertainty, estimated at +-2.7%. We expect that once all sub-dominant partonic reactions are accounted for, and work in this direction is ongoing, the perturbative theoretical uncertainty for this observable could drop below +-2%. Our calculation demonstrates the power of our computational approach and proves it can be successfully applied to all processes at hadron colliders for which high-precision analyses are needed.
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Top quark mass measured at 172.17 ± 1.56 GeV via unbinned maximum-likelihood fit to m(ℓ μ⁺μ⁻) in ATLAS Run 2 data using J/ψ decays.
NNLO QCD calculations using the MaunaKea code enhance c cbar and b bbar production cross sections by up to a factor of two over NLO predictions, reduce scale uncertainties, and match experimental data from 10 GeV to 14 TeV while suggesting PDF and mass constraints.
Differential cross sections for ttbar production in e+e-, mu+mu-, and e mu channels measured versus dineutrino pT and azimuthal separation using 138 fb-1 of 13 TeV CMS data, unfolded to particle level with unregularized least squares and found consistent with SM and MC predictions.
ATLAS reports the first measurement of the complete angular coefficients and pT-differential cross sections for W+ and W- bosons in full lepton phase space at 13 TeV, finding agreement with QCD predictions up to order α_S².
No evidence for charginos and neutralinos in R-parity violating Higgs-decay channels; masses 150-1100 GeV excluded at 95% CL assuming equal lepton branching fractions.
No excess observed in search for vector-like T-quarks in Ht channel; 95% CL mass limits set at 1.40 TeV (SU(2) singlet), 1.56 TeV (doublet), and 1.66 TeV (100% BR to Ht).
No significant excess observed; gauginos excluded up to 1.2 TeV in specific supersymmetric decay scenarios.
Reviews selected challenges in Monte Carlo event generators for future lepton colliders including electroweak corrections, initial-state radiation, beam dynamics, perturbative QCD and non-perturbative modelling.
citing papers explorer
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Measurement of the top-quark mass using decays with a $J/\psi$ meson at $\sqrt{s}=$13 TeV with the ATLAS detector
Top quark mass measured at 172.17 ± 1.56 GeV via unbinned maximum-likelihood fit to m(ℓ μ⁺μ⁻) in ATLAS Run 2 data using J/ψ decays.
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Measurement of the dineutrino system kinematic variables in dileptonic top quark pair production in proton-proton collisions at$\sqrt{s}$ = 13 TeV
Differential cross sections for ttbar production in e+e-, mu+mu-, and e mu channels measured versus dineutrino pT and azimuthal separation using 138 fb-1 of 13 TeV CMS data, unfolded to particle level with unregularized least squares and found consistent with SM and MC predictions.
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Measurement of the $W$-boson angular coefficients and transverse momentum in $pp$ collisions at $\sqrt{s}=$ 13 TeV with the ATLAS detector
ATLAS reports the first measurement of the complete angular coefficients and pT-differential cross sections for W+ and W- bosons in full lepton phase space at 13 TeV, finding agreement with QCD predictions up to order α_S².
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Search for signatures of electroweakinos with photons, jets, and large missing transverse momentum in $\sqrt{s}=13$ TeV pp collisions with the ATLAS detector
No significant excess observed; gauginos excluded up to 1.2 TeV in specific supersymmetric decay scenarios.