Line Segment Tracking: Improving the Phase 2 CMS High Level Trigger Tracking with a Novel, Hardware-Agnostic Pattern Recognition Algorithm

TL;DR

This paper introduces Line Segment Tracking (LST), a novel, hardware-agnostic, parallelizable pattern recognition algorithm designed to improve charged particle reconstruction efficiency and speed in high-luminosity collider experiments.

Contribution

The paper presents LST, a new pattern recognition algorithm that is fully parallelizable and hardware-agnostic, enhancing particle tracking performance in CMS HL-LHC High Level Trigger.

Findings

LST improves physics performance over existing algorithms.

LST reduces processing time in the CMS HLT environment.

LST demonstrates compatibility with GPU hardware.

Abstract

Charged particle reconstruction is one the most computationally heavy components of the full event reconstruction of Large Hadron Collider (LHC) experiments. Looking to the future, projections for the High Luminosity LHC (HL-LHC) indicate a superlinear growth for required computing resources for single-threaded CPU algorithms that surpass the computing resources that are expected to be available. The combination of these facts creates the need for efficient and computationally performant pattern recognition algorithms that will be able to run in parallel and possibly on other hardware, such as GPUs, given that these become more and more available in LHC experiments and high-performance computing centres. Line Segment Tracking (LST) is a novel such algorithm which has been developed to be fully parallelizable and hardware agnostic. The latter is achieved through the usage of the Alpaka library. The LST algorithm has been tested with the CMS central software as an external package and has been used in the context of the CMS HL-LHC High Level Trigger (HLT). When employing LST for pattern recognition in the HLT tracking, the physics and timing performances are shown to improve with respect to the ones utilizing the current pattern recognition algorithms. The latest results on the usage of the LST algorithm within the CMS HL-LHC HLT are presented, along with prospects for further improvements of the algorithm and its CMS central software integration.