LHCb Topological Trigger Reoptimization
Name
Williams_LHCb topological.pdf
Size
1.39 MB
Format
Adobe PDF
Checksum (MD5)
4eba0774a1104e1e0cb8b7024e23f30d
Author(s)
Likhomanenko, Tatiana
Khairullin, Egor
Rogozhnikov, Alex
Ustyuzhanin, Andrey
Ilten, Philip J
Williams, Michael
Date Issued
December 2015
Journal
Journal of Physics: Conference Series
Publisher
IOP Publishing
Citation
Likhomanenko, Tatiana; Ilten, Philip; Khairullin, Egor; Rogozhnikov, Alex; Ustyuzhanin, Andrey and Williams, Michael. “LHCb Topological Trigger Reoptimization.” Journal of Physics: Conference Series 664, no. 8 (December 2015): 082025. © 2015 IOP Publishing
Version
Final published version
Abstract
The main b-physics trigger algorithm used by the LHCb experiment is the so- called topological trigger. The topological trigger selects vertices which are a) detached from the primary proton-proton collision and b) compatible with coming from the decay of a b-hadron. In the LHC Run 1, this trigger, which utilized a custom boosted decision tree algorithm, selected a nearly 100% pure sample of b-hadrons with a typical efficiency of 60-70%; its output was used in about 60% of LHCb papers. This talk presents studies carried out to optimize the topological trigger for LHC Run 2. In particular, we have carried out a detailed comparison of various machine learning classifier algorithms, e.g., AdaBoost, MatrixNet and neural networks. The topological trigger algorithm is designed to select all 'interesting" decays of b-hadrons, but cannot be trained on every such decay. Studies have therefore been performed to determine how to optimize the performance of the classification algorithm on decays not used in the training. Methods studied include cascading, ensembling and blending techniques. Furthermore, novel boosting techniques have been implemented that will help reduce systematic uncertainties in Run 2 measurements. We demonstrate that the reoptimized topological trigger is expected to significantly improve on the Run 1 performance for a wide range of b-hadron decays.
MIT Department
Massachusetts Institute of Technology. Department of Physics
Terms of Use
Creative Commons Attribution 3.0 Unported license
Persistent DSpace Link
DOI of Published Version
https://doi.org/10.1088/1742-6596/664/8/082025
