Top-quark initiated processes at high-energy hadron colliders

  • Tao Han
  • Josh Sayre
  • Susanne Westhoff
Open Access
Regular Article - Theoretical Physics


In hadronic collisions at high energies, the top-quark may be treated as a parton inside a hadron. Top-quark initiated processes become increasingly important since the top-quark luminosity can reach a few percent of the bottom-quark luminosity. In the production of a heavy particle H with mass m H > m t , treating the top-quark as a parton allows us to resum large logarithms log(m H 2 /m t 2 ) arising from collinear splitting in the initial state. We quantify the effect of collinear resummation at the 14-TeV LHC and a future 100-TeV hadron collider, focusing on the top-quark open-flavor process \( gg\to t\overline{t}H \) in comparison with \( t\overline{t}\to H \) and tgtH at the leading order (LO) in QCD. We employ top-quark parton distribution functions with appropriate collinear subtraction and power counting. We find that (1) collinear resummation enhances the inclusive production of a heavy particle with m H ≈ 5 TeV (0.5 TeV) by more than a factor of two compared to the open-flavor process at a 100-TeV (14-TeV) collider; (2) top-quark mass effects are important for scales m H near the top-quark threshold, where the cross section is largest. We advocate a modification of the ACOT factorization scheme, dubbed m-ACOT, that consistently treats heavy-quark masses in hadronic collisions with two initial heavy quarks; (3) the scale uncertainty of the total cross section in m-ACOT is of about 20% at the LO. While a higher-order calculation is indispensable for a precise prediction, the LO cross section is well described by the process \( t\overline{t}\to H \) using an effective factorization scale significantly lower than m H . We illustrate our results by the example of a heavy spin-0 particle. Our main results also apply to the production of particles with spin-1 and 2.


Beyond Standard Model Resummation QCD 


Open Access

This article is distributed under the terms of the Creative Commons Attribution License (CC-BY 4.0), which permits any use, distribution and reproduction in any medium, provided the original author(s) and source are credited.


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Copyright information

© The Author(s) 2015

Authors and Affiliations

  1. 1.PITTsburgh Particle-physics Astro-physics & Cosmology Center (PITT-PACC), Department of Physics & AstronomyUniversity of PittsburghPittsburghUnited States

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