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Event generation with exponential scaling in multiplicity using AmpliCol

Frederix, Rikkert LU orcid and Vitos, Timea (2026) In Journal of High Energy Physics 2026(4).
Abstract

Efficient generation of LHC events is hindered by the rapidly rising cost of evaluating QCD matrix elements with increasing multiplicity. We build on a recently proposed two-step strategy in which unweighted events are first generated using the leading-colour (LC) approximation and then reweighted to full-colour (FC) accuracy, utilising the LC integration efficiency while recovering the exact FC prediction. In this work we extend the method to general Standard Model processes and present AmpliCol, a standalone implementation designed for LHC collisions. We benchmark multi-jet, tt¯+jets, ZZ+jets, and Drell-Yan+jets production, measuring the time required to obtain a fixed number of unweighted events at FC accuracy. Across all processes,... (More)

Efficient generation of LHC events is hindered by the rapidly rising cost of evaluating QCD matrix elements with increasing multiplicity. We build on a recently proposed two-step strategy in which unweighted events are first generated using the leading-colour (LC) approximation and then reweighted to full-colour (FC) accuracy, utilising the LC integration efficiency while recovering the exact FC prediction. In this work we extend the method to general Standard Model processes and present AmpliCol, a standalone implementation designed for LHC collisions. We benchmark multi-jet, tt¯+jets, ZZ+jets, and Drell-Yan+jets production, measuring the time required to obtain a fixed number of unweighted events at FC accuracy. Across all processes, the runtime exhibits a stable exponential scaling with multiplicity, far milder than the factorial growth of conventional matrix-element generators. This demonstrates that the AmpliCol code enables efficient event generation at multiplicities that are otherwise computationally prohibitive.

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author
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organization
publishing date
type
Contribution to journal
publication status
published
subject
keywords
Automation, Specific QCD Phenomenology
in
Journal of High Energy Physics
volume
2026
issue
4
article number
192
publisher
Springer
external identifiers
  • scopus:105037485029
ISSN
1029-8479
DOI
10.1007/JHEP04(2026)192
language
English
LU publication?
yes
id
c08daf5f-1684-4f6b-85f2-84210f16ce3b
date added to LUP
2026-07-10 13:45:05
date last changed
2026-07-10 13:45:34
@article{c08daf5f-1684-4f6b-85f2-84210f16ce3b,
  abstract     = {{<p>Efficient generation of LHC events is hindered by the rapidly rising cost of evaluating QCD matrix elements with increasing multiplicity. We build on a recently proposed two-step strategy in which unweighted events are first generated using the leading-colour (LC) approximation and then reweighted to full-colour (FC) accuracy, utilising the LC integration efficiency while recovering the exact FC prediction. In this work we extend the method to general Standard Model processes and present AmpliCol, a standalone implementation designed for LHC collisions. We benchmark multi-jet, tt¯+jets, ZZ+jets, and Drell-Yan+jets production, measuring the time required to obtain a fixed number of unweighted events at FC accuracy. Across all processes, the runtime exhibits a stable exponential scaling with multiplicity, far milder than the factorial growth of conventional matrix-element generators. This demonstrates that the AmpliCol code enables efficient event generation at multiplicities that are otherwise computationally prohibitive.</p>}},
  author       = {{Frederix, Rikkert and Vitos, Timea}},
  issn         = {{1029-8479}},
  keywords     = {{Automation; Specific QCD Phenomenology}},
  language     = {{eng}},
  number       = {{4}},
  publisher    = {{Springer}},
  series       = {{Journal of High Energy Physics}},
  title        = {{Event generation with exponential scaling in multiplicity using AmpliCol}},
  url          = {{http://dx.doi.org/10.1007/JHEP04(2026)192}},
  doi          = {{10.1007/JHEP04(2026)192}},
  volume       = {{2026}},
  year         = {{2026}},
}