Electroweak production of top-quark pairs ine+e−annihilation at NNLO in QCD: The vector current contributions

Abstract

We report on a calculation of the vector current contributions to the electroweak production of top quark pairs in e + e − annihilation at next-to-next-to-leading order in Quantum Chromodynamics.Our setup is fully differential and can be used to calculate any infrared-safe observable. The real emission contributions are handled by a next-to-next-to-leading order generalization of the phasespace slicing method. We demonstrate the power of our technique by considering its application to various inclusive and exclusive observables.

Power corrections in the N -jettiness subtraction scheme

“…The idea of using a physical observable to isolate singularities and construct subtraction terms at higher orders stems from the idea of q T -subtraction [6], which uses the transverse momentum of a color-singlet object to accomplish NNLO computations for color-singlet processes. This was further generalized to calculate top-quark decays [13] and tt production in leptonic collisions [14]. The N -jettiness subtraction scheme further extends this idea to handle processes with arbitrary final-state jets.…”

“…Assuming the collinear scaling q · k ∼ Q 2 , p a · k ∼ Q 2 τ 1 and z ∼ 1, we find the phase space for the collinear sector in the method of regions approach 14) where Ω 2−2 is the 2 − 2 dimensional solid angle from k ⊥ . The phase space for the soft sector and the zero bin can be derived straightforwardly from eq.…”

Probing top-Z dipole moments at the LHC and ILC

“…NNLO QCD corrections to the top-pair production at threshold have received significant attention in the past (see [49] and reference therein), and progress is being made on the N 3 LO corrections [50][51][52] at threshold. In the continuum, certain differential results at NNLO QCD have recently been presented recently [53][54][55]. Both the NLO scale uncertainty and JHEP08(2015)044 the NNLO corrections at √ s = 500 GeV are at the level of 1%-2%, indicating a very good perturbative convergence [53].…”

Validity of Padé approximations in vacuum polarization at three- and four-loop order

“…Independently, the cross section corresponding to the imaginary part of the vacuum polarization was computed numerically in Refs. [16,17]. Corrections involving both massive and massless quarks were obtained already much earlier in Ref.…”