Wydział Fizyki

Dataset contains data related to the study of the prospects for long-lived particle (LLPs) observation with the International Large Detector (ILD), operating at the International Linear Collider (ILC) at the collision energy of 250 GeV. Neutral LLP production, resulting in a displaced vertex signature inside the ILD’s time projection chamber (TPC), is considered for two experimentally challenging scenarios: the first involving very soft final states due to a small mass splitting between a heavy LLP and the dark matter particle to which it decays, and the second with production of a light and therefore highly boosted LLP resulting in almost colinear vertex tracks. Results were described in the publication "Searching for displaced vertices with a gaseous tracker for a future e⁺e⁻ Higgs factory" published in Journal of High Energy Physics, JHEP02(2025)112.

This research was part of the project "Realistic simulations of exotic processes at future e⁺e^- colliders" funded by National Science Centre, Poland, under grant agreement nr 2021/43/B/ST2/01778.

Methodology

The study was based on large Monte Carlo event samples generated within the ILD collaboration for the Standard Model processes and dedicated samples for considered "new physics" processes generated by authors. All samples resulted from the physics process simulation with the WHIZARD framework, followed by full simulation of the ILD detector response in DD4HEP, based on GEANT4 package, and event reconstruction based on iLCSoft, tools provided by the LCC generator working group and the ILD software working group. Sample production was based on computing services provided by the ILC Virtual Organization, supported by the national resource providers of the EGI Federation and the Open Science GRID. Standard Model samples had to be reprocessed with the updated track reconstruction.

Event sample files used for the analysis are stored on GRID.

Software tools used

• WHIZARD Event Generator web page: https://whizard.hepforge.org/
• DD4hep - Detector Description Toolkit for High Energy Physics: https://dd4hep.web.cern.ch/dd4hep/
• List of Monte Carlo event samples produced by the ILD collaboration: https://ild.ngt.ndu.ac.jp/elog/dbd-prod/
• iLCSsoft - linear collider software repository: https://github.com/iLCSoft
• Modified reconstruction algorithm: https://github.com/jfklama/MarlinUtil/tree/HelixClassFix

Files stored

• CSV files with final analysis results: expected limits on the LLPs production cross section, for the two considered benchmarks and two selection cut levels, as a function of the decay length,
• PDF and PNG files of the figures showing these limits (Fig. 9 from the paper).