# Explicit Jet Veto as a Tool to Purify the Underlying Event in the Drell-Yan Process Using CMS Open Data

## TL;DR

This paper introduces a jet veto method to isolate the underlying event in Drell-Yan processes, verified on CMS Open Data, offering a new approach to study the underlying event in real collision data.

## Contribution

It proposes and tests a jet veto technique to better isolate the underlying event in high-energy collisions using real CMS data, a novel application.

## Key findings

- Jet veto effectively reduces contamination from extra jets.
- Method successfully applied to CMS Open Data.
- First real-data validation of jet veto for underlying event analysis.

## Abstract

The underlying event is an important part of high-energy collision events. In the event generators, the underlying event is tuned by fits to collision data. Usually, the underlying event observables are affected by the existence of extra jets and it is difficult to find a part of the phase space which is dominated by the underlying event. In this paper, we suggest to veto the jets in the considered region to disentangle these effects. The idea is verified to work on CMS Open Data. To our knowledge, it is the first time that such ideas are tested on real collision data.