# An automated bandwidth division for the LHCb upgrade trigger

## TL;DR

This paper introduces an automated system to efficiently divide data processing bandwidth in a particle physics experiment.

## Contribution

The novel contribution is an automated bandwidth division tool for optimizing trigger selections in the LHCb experiment.

## Key findings

- The automated tool optimizes trigger selections to maximize signal efficiency while capping output rate.
- The system was applied to 35 algorithms across 80 physics channels in the LHCb experiment.
- The approach ensures equitable bandwidth division for the experiment's physics program.

## Abstract

The upgraded Large Hadron Collider beauty (LHCb) experiment is the first detector based at a hadron collider using a fully software-based trigger. The first ‘High Level Trigger’ stage (HLT1) reduces the event rate from 30 MHz to approximately 1 MHz based on reconstruction criteria from the tracking system, and consists of \documentclass[12pt]{minimal}
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\begin{document}$$\mathcal {O}(100)$$\end{document}O(100) trigger selections implemented on Graphics Processing Units (GPUs). These selections are further refined following the full offline-quality reconstruction at the second stage (HLT2) prior to saving for analysis. An automated bandwidth division has been performed to equitably divide this 1 MHz HLT1 Output Rate (OR) between the signals of interest to the LHCb physics program. This was achieved by optimizing a set of trigger selections that maximize efficiency for signals of interest to LHCb while keeping the total HLT1 readout capped to a maximum. The bandwidth division tool has been used to determine the optimal selection for 35 selection algorithms over 80 characteristic physics channels.