{"about":{"site":"https://codewithpapers.app","non_affiliation":"Code with Papers and Syntology are not affiliated with, endorsed by, or sponsored by Papers with Code, Meta, or the pwc-archive mirror.","licence":"CC BY-SA 4.0","licence_url":"https://creativecommons.org/licenses/by-sa/4.0/legalcode","attribution":"https://codewithpapers.app/attribution","modified":"archive material modified by Syntology; see the attribution page"},"url":"/paper/alternative-angular-variables-for-suppression","title":"Alternative angular variables for suppression of QCD multijet events in new physics searches with missing transverse momentum at the LHC","arxiv_id":"1803.07942","date":"2018-03-21","proceeding":null,"authors":["Tai Sakuma","Henning Flaecher","Dominic Smith"],"abstract":"We introduce three alternative angular variables-denoted by $\\tilde{\\omega}_\\text{min}$, $\\hat{\\omega}_\\text{min}$, and $\\chi_\\text{min}$-for QCD multijet event suppression in supersymmetry searches in events with large missing transverse momentum in proton-proton collisions at the LHC at CERN. In searches in all-hadronic final states in the CMS and ATLAS experiments, the angle $\\Delta\\varphi_i$, the azimuthal angle between a jet and the missing transverse momentum, is widely used to reduce QCD multijet background events with large missing transverse momentum, which is primarily caused by a jet momentum mismeasurement or neutrinos in hadron decays-the missing transverse momentum is aligned with a jet. A related angular variable-denoted by $\\Delta\\varphi^*_\\text{min}$, the minimum of the azimuthal angles between a jet and the transverse momentum imbalance of the other jets in the event-is used instead in a series of searches in all-hadronic final states in CMS to suppress QCD multijet background events to a negligible level. In this paper, before introducing the alternative variables, we review the variable $\\Delta\\varphi^*_\\text{min}$ in detail and identify room for improvement, in particular, to maintain good acceptances for signal models with high jet multiplicity final states. Furthermore, we demonstrate with simulated event samples that $\\hat{\\omega}_\\text{min}$ and $\\chi_\\text{min}$ considerably outperform $\\Delta\\varphi^*_\\text{min}$ and $\\Delta\\varphi_i$ in rejecting QCD multijet background events and that $\\hat{\\omega}_\\text{min}$ and $\\tilde{\\omega}_\\text{min}$ are also useful for reducing the total standard model background events.","url_abs":"http://arxiv.org/abs/1803.07942v2","url_pdf":"http://arxiv.org/pdf/1803.07942v2.pdf","source":{"archive":"pwc-archive (Hugging Face), CC BY-SA 4.0","snapshot":"2025-07-28","licence_url":"https://creativecommons.org/licenses/by-sa/4.0/legalcode","row_kind":"links_only","authors_date_abstract":"arXiv metadata, CC0 1.0 (https://info.arxiv.org/help/license), from the Kaggle arXiv metadata snapshot of 2026-09-12"},"code_links":[{"paper_slug":"alternative-angular-variables-for-suppression","repo_url":"https://github.com/TaiSakuma/altdphi","is_official":1,"mentioned_in_paper":1,"mentioned_in_github":1,"framework":"none","reach":null}],"tasks":[],"methods":[],"datasets_introduced":[],"methods_introduced":[],"results":[],"syntology":{"atlas_url":null,"mcp":null,"developers":"https://syntology.ai/developers"},"arxiv_metadata":null,"syntology_extracted_results":null}