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Exploring hadronic decays of the Higgs boson at the LHC ATLAS experiment and its HL-LHC upgrade

Applicant Sfyrla Anna
Number 175597
Funding scheme Project funding
Research institution Département de physique nucléaire et corpusculaire Université de Genève
Institution of higher education University of Geneva - GE
Main discipline Particle Physics
Start/End 01.02.2018 - 31.03.2020
Approved amount 315'592.00
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Keywords (7)

upgrade; particle flow; Higgs couplings; multi-jets; trigger; flavor tagging; top physics

Lay Summary (French)

Lead
Le LHC a fourni des quantités remarquables de données de collisions des protons à de différents régimes énergétiques. Malgré le grand succès des expériences du LHC et les résultats exceptionnels obtenus, les questions urgentes du Modèle Standard restent sans réponse. L'étude détaillée des propriétés du boson de Higgs est donc cruciale, en particulier dans les processus de production les plus faibles, tels que ttH et HH, et les états finaux les plus compliqués, tels que les canaux des désintégrations hadroniques.
Lay summary
Dans le cadre de ce projet, nous préparons le terrain pour l'acquisition et l'exploitation optimales des données du LHC par l'expérience ATLAS ainsi que par sa mise-à-niveau pour le LHC de haute luminosité (HL-LHC), en ciblant la mesure des propriétés de Higgs sensibles à la nouvelle physique. Au cours de deux prochaines années et en vue d'atteindre cet objectif, nous optimiserons la performance de la reconstruction 'particle-flow' dans l'experience ATLAS. Nous mesurerons les processus du Modèle Standard qui constituent les bruits-de-fond les plus signifiants pour ces modes de production du boson de Higgs dans les états finaux hadroniques. Nous travaillerons également à la collecte optimale des données au HL-LHC ATLAS grâce à la réalisation d'une nouvelle capacité de déclenchement basée sur la reconstruction des traces.

Les connaissances acquises dans la recherche en cours ouvriront la voie à la comprehension des modes de production et des canaux de désintégration du boson de Higgs les plus rares, ainsi qu'à leur accessibilité dans le cadre du LHC Run 2 et dans le futur. Les améliorations de la capacité de déclenchement augmenteront le potentiel de l'expérience ATLAS dans son ensemble. 
Direct link to Lay Summary Last update: 11.01.2018

Responsible applicant and co-applicants

Employees

Publications

Publication
Measurements of top-quark pair single- and double-differential cross-sections in the all-hadronic channel in pp collisions at √s = 13 TeV using the ATLAS detector
ATLASCollaboration (2020), Measurements of top-quark pair single- and double-differential cross-sections in the all-hadronic channel in pp collisions at √s = 13 TeV using the ATLAS detector, ATLAS collaboration, Switzerland.
Search for new phenomena in final states with large jet multiplicities and missing transverse momentum using s√=13 TeV proton-proton collisions recorded by ATLAS in Run 2 of the LHC
ATLASCollaboration (2020), Search for new phenomena in final states with large jet multiplicities and missing transverse momentum using s√=13 TeV proton-proton collisions recorded by ATLAS in Run 2 of the LHC, ATLAS collaboration, Switzerland.
Design of the ATLAS phase-II hardware-based tracking processor
Poggi Riccardo (2019), Design of the ATLAS phase-II hardware-based tracking processor, in Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detector, 936, 305-307, Elsevier, Frontier Detectors for Frontier Physics: 14th Pisa Meeting on Advanced Detectors 936, 305-307.
Digital Signal Processing in FPGA for Particle Track Reconstruction at the HL-LHC ATLAS
Poggi Riccardo (2019), Digital Signal Processing in FPGA for Particle Track Reconstruction at the HL-LHC ATLAS, in 2019 8th International Conference on Modern Circuits and Systems Technologies (MOCAST), Thessaloniki, GreeceIEEE Xplore, MOCAST.
Impact of Alternative Inputs and Jet Grooming on Large-R Jet Performance
ATLASCollaboration (2019), Impact of Alternative Inputs and Jet Grooming on Large-R Jet Performance, ATLAS collaboration, Switzerland.
Performance of missing transverse momentum reconstruction with the ATLAS detector using proton–proton collisions at 13 TeV
ATLAS Collaboration (2018), Performance of missing transverse momentum reconstruction with the ATLAS detector using proton–proton collisions at 13 TeV, in The European Physical Journal C, 78(11), 903-903.
Object-based missing transverse momentum significance in the ATLAS detector
ATLASCollaboration (2018), Object-based missing transverse momentum significance in the ATLAS detector, ATLAS collaboration, Switzerland.
Searches for electroweak signatures of supersymmetry at ATLAS and CMS
Khoo T.J. (2018), Searches for electroweak signatures of supersymmetry at ATLAS and CMS, ARISF, Italy.

Collaboration

Group / person Country
Types of collaboration
ATLAS collaboration Switzerland (Europe)
- in-depth/constructive exchanges on approaches, methods or results
- Publication
- Research Infrastructure
- Exchange of personnel

Scientific events

Active participation

Title Type of contribution Title of article or contribution Date Place Persons involved
LHCTOPWG2020 Talk given at a conference All-hadronic resolved differential cross-section measurement 13.04.2020 Online event due to Covid-19 pandemic, Switzerland Poggi Riccardo;
Moriond QCD Talk given at a conference Strong SUSY at ATLAS and CMS 28.03.2020 Moriond (The conference was finally cancelled due to the Covid-19 pandemic), Italy Khoo Teng Jian;
CHEP2019 Talk given at a conference Implementation of the ATLAS trigger within the multi-threaded AthenaMT framework 01.10.2019 Adelaide, Australia Khoo Teng Jian;
MOCAST Talk given at a conference Digital signal processing in FPGA for particle track reconstruction at the HL-LHC ATLAS 06.05.2019 Thesaloniki, Greece Poggi Riccardo;
LHCP2018 Talk given at a conference Status of ATLAS and CMS upgrades on tracking and TDAQ and future prospects 04.06.2018 Bologna, Italy Sfyrla Anna;
Frontier Detectors for Frontier Physics XIV Pisa Meeting on Advanced Detectors, Poster Design of the ATLAS phase-II hardware-based tracking processor 27.05.2018 La Biodola, Italy Poggi Riccardo;
Moriond 2018 Talk given at a conference Searches for electroweak SUSY with ATLAS and CMS 05.03.2018 La Thuile, Italy Khoo Teng Jian;


Communication with the public

Communication Title Media Place Year
Talks/events/exhibitions CERN Open Days 2019 Western Switzerland 2019
Talks/events/exhibitions Nuit de la Science Western Switzerland 2018

Awards

Title Year
ATLAS Outstanding Achievement Award for Khoo's ‘creative and dedicated contributions to the measurement of jet energy and missing transverse momentum’ 2019
Best Student Paper and Presentation on Electronics for innovation, quality of work as well as the presenter’s ability to convey the paper's content Awarded at the MOCAST conference 2019

Associated projects

Number Title Start Funding scheme
173598 FLARE: Maintenance & Operation for the LHC Experiments 2017-2020 01.04.2017 FLARE
173601 FLARE - ATLAS Detector Operation and Phase-II Upgrade at the CERN Large Hadron Collider (LHC) 01.04.2017 FLARE
159900 Particle flow in the searches for supersymmetry with ATLAS 01.02.2016 Project funding
207431 Searching for new physics at the LHC 01.05.2022 Project funding
192276 Maximising the physics reach of the LHC collisions at the ATLAS and FASER experiments 01.04.2020 Project funding
201478 FLARE - ATLAS Detector Operation and Phase-II Upgrade at the CERN Large Hadron Collider (LHC) 01.04.2021 FLARE
159900 Particle flow in the searches for supersymmetry with ATLAS 01.02.2016 Project funding

Abstract

The ATLAS experiment is one of the two large general purpose experiments at CERN's Large Hadron Collider (LHC). ATLAS has operated with outstanding performance and produced numerous physics results, which include the discovery of the Higgs boson in 2012. Following that discovery, the physics program of the experiment focuses on measurements of the properties of the new particle, measurements of the Standard Model particles and interactions and searches for new phenomena which could give answers to the open questions that the Standard Model leaves unanswered. The searches have so far revealed no compelling indication for new physics, resulting in stringent constraints set to exotic models and theories.The measurements of the properties of the Standard Model constituents, including those of the Higgs boson, become more and more crucial as deviations from predictions can hint new physics. Large precision has been achieved in many production processes and decay channels of the Higgs boson, leading to precise measurements of couplings consistent with the Standard Model. Some of the most important properties, however, require further precision. Such properties are the top and bottom Yukawa couplings, the dominant ones among the Higgs couplings, as well as the Higgs self-coupling. The former two can be simultaneously measured via ttH production with H to bb. The latter, HH production, has largest branching ratios for H to bb, leading to a four b-quark signature. These couplings are the least constrained ones due to experimental difficulties associated with the final states, but also due to the low cross-section with which the production is occurring at the LHC. The High-Luminosity LHC upgrade (HL-LHC), envisaged for 2025, is planned to deliver an order of magnitude more data than previous runs, giving access to processes that were previously inaccessible, such as the HH production.Both in the current LHC phase and in the future HL-LHC, enhanced phase-space in triggering, better reconstruction, better understanding of the background processes and improved methods to measure them are key aspects towards achieving the desired measurements of the Higgs couplings. The present funding request targets exactly these aspects. In the twenty-month period, from 02/2018 till 10/2019, we will:- improve flavor tagging using particle flow, with a direct impact to the H to bb mass resolution;- study the background processes tt plus (heavy flavor) jets and ttZ, in the fully hadronic final states, which we know well from the SUSY multi-jet searches we are currently pursuing;- evaluate, at HL-LHC conditions, the sensitivity of ttH and HH in fully hadronic channels and produce combinations with other channels, particularly in the challenging case of HH;- improve, at the HL-LHC ATLAS trigger and data acquisition system, the currently compromised hadronic trigger capability using track-based pile-up mitigation methods implemented at hardware; develop simulation and performance studies, as well as a demonstrator to test firmware, algorithms and resources, in the laboratory and in testbeam.To achieve these goals, we are asking SNF to finance a postdoctoral researcher for twenty months as well as two Ph.D. students for the same period. The experience gained by this work will be the stepping stone and a solid basis for further research that will span from measurements of Higgs couplings with LHC data to the construction of a hardware track trigger for the HL-LHC ATLAS upgrade.
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