Abstract
We compute the contribution of third generation quarks (t, b) to the two-loop amplitude for on-shell W boson pair production in gluon fusion gg → WW. We present plots for the amplitude across partonic phase space as well as reference values for two kinematic points. The master integrals are efficiently evaluated by numerically solving a system of ordinary differential equations.
Highlights
DefinitionsWe study the contribution of third generation quarks (t, b) to the amplitude of the process g(p1) + g(p2) → W (p3) + W (p4),
Massive fermion propagators that appear when top quark contributions are considered make calculations significantly more demanding compared to the massless case
We compute the contribution of third generation quarks (t, b) to the two-loop amplitude for on-shell W boson pair production in gluon fusion gg → W W
Summary
We study the contribution of third generation quarks (t, b) to the amplitude of the process g(p1) + g(p2) → W (p3) + W (p4),. The axial-vector term is odd under parity transformations; its decomposition is possible in terms of the tensor structures SIμν in eq (2.5). If masses of two quarks in a single generation are equal, the parity-odd contribution vanishes [1, 7, 8, 25] and it is absent in amplitudes involving only massless quark loops [12, 13]. Throughout this paper the Levi-Civita symbol εμνρσ is defined using the convention of FORM ε0123 = −i. This γ5-prescription is much more convenient to work with in dimensional regularisation, it violates Ward identities of the axial current. Where JA and JbA stand for renormalised and unrenormalised axial currents respectively
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