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Development and validation of HERWIG 7 tunes from CMS underlying-event measurements
A M Sirunyan1, A Tumasyan1, W Adam2
1Yerevan Physics Institute, Yerevan, Armenia.
The European Physical Journal. C, Particles and Fields
|November 2, 2021
Summary
New tunes for the PYTHIA event generator improve descriptions of multiple-parton interactions and colour reconnection. These tunes, fitted to CMS data, best describe proton-proton collision data when using leading-order parton distribution functions for multiple-parton interactions.
Area of Science:
- High Energy Physics
- Particle Physics
- Computational Physics
Background:
- The PYTHIA event generator is crucial for simulating particle collisions.
- Accurate modeling of the underlying event, including multiple-parton interactions (MPI) and colour reconnection, is essential for precise physics predictions.
- Existing PYTHIA tunes require updates to match recent experimental data.
Purpose of the Study:
- To develop and present new sets of parameters (tunes) for the PYTHIA event generator's underlying-event model.
- To improve the description of multiple-parton interactions (MPI) and colour reconnection in PYTHIA.
- To validate these new tunes against experimental data from the CMS experiment.
Main Methods:
- Fit new PYTHIA tunes to minimum-bias data collected by the CMS experiment at various center-of-mass energies.
- Utilized the NNPDF 3.1 next-to-next-to-leading-order parton distribution function (PDF) set for the parton shower.
- Employed either leading-order or next-to-next-to-leading-order PDF sets for simulating MPI and beam remnants.
Main Results:
- New tunes were developed and tested for their ability to describe experimental data.
- Predictions were made for various observables in both electron-positron and proton-proton collisions.
- Tunes using a leading-order PDF for MPI simulation demonstrated the best agreement with the experimental data.
Conclusions:
- The newly developed PYTHIA tunes provide a reasonable description of the underlying event.
- The tunes utilizing leading-order PDFs for MPI simulation offer the most accurate description of the analyzed data.
- These improved tunes will enhance the precision of future particle physics simulations and analyses.
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