Accelerating LHC event generation with simplified pilot runs and fast PDFs

Understand

Poor computing efficiency of precision event generators for LHC physics has become a bottleneck for Monte-Carlo event simulation campaigns.

• We provide solutions to this problem by focusing on two major components of general-purpose event generators: The PDF evaluator and the matrix-element generator.
• For a typical production setup in the ATLAS experiment, we show that the two can consume about 80% of the total runtime.
• Using NLO simulations of $pp\to\ell^+\ell^-+\text{jets}$ and $pp\to t\bar{t}+\text{jets}$ as an example, we demonstrate that the computing footprint of LHAPDF and Sherpa can be reduced by factors of order 10, while maintaining the formal accuracy of the event sample.