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Title: Two loop correction to interference in $$gg \to ZZ$$

Here, we present results for the production of a pair of on-shell Z bosons via gluon-gluon fusion. This process occurs both through the production and decay of the Higgs boson, and through continuum production where the Z boson couples to a loop of massless quarks or to a massive quark. We calculate the interference of the two processes and its contribution to the cross section up to and including order O(α$$_{s}^{3}$$ ). The two-loop contributions to the amplitude are all known analytically, except for the continuum production through loops of top quarks of mass m. The latter contribution is important for the invariant mass of the two Z bosons, (as measured by the mass of their leptonic decay products, m$$_{4l}$$), in a regime where m$$_{4l}$$ ≥ 2m because of the contributions of longitudinal bosons. We examine all the contributions to the virtual amplitude involving top quarks, as expansions about the heavy top quark limit combined with a conformal mapping and Padé approximants. Comparison with the analytic results, where known, allows us to assess the validity of the heavy quark expansion, and it extensions. We give results for the NLO corrections to this interference, including both real and virtual radiation.
Authors:
 [1] ;  [2] ;  [3] ;  [3]
  1. Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States)
  2. Univ. of Durham, Durham (United Kingdom)
  3. RWTH Aachen Univ., Aachen (Germany)
Publication Date:
OSTI Identifier:
1287382
Report Number(s):
FERMILAB-PUB--16-113-T; IPPP--16-28; TTK--16-12; arXiv:1605.01380
Journal ID: ISSN 1029-8479; 1455802
Grant/Contract Number:
AC02-07CH11359
Type:
Accepted Manuscript
Journal Name:
Journal of High Energy Physics (Online)
Additional Journal Information:
Journal Name: Journal of High Energy Physics (Online); Journal Volume: 2016; Journal Issue: 8; Journal ID: ISSN 1029-8479
Publisher:
Springer Berlin
Research Org:
Fermi National Accelerator Laboratory (FNAL), Batavia, IL (United States)
Sponsoring Org:
USDOE Office of Science (SC), High Energy Physics (HEP) (SC-25)
Country of Publication:
United States
Language:
English
Subject:
72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS NLO computations; QCD phenomenology