Development Of Machine Learning Trigger Algorithms And Search For Higgs Boson Pair Production
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Development Of Machine Learning Trigger Algorithms And Search For Higgs Boson Pair Production
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Author : Jona Motta
language : en
Publisher: Springer
Release Date : 2025-07-27
Development Of Machine Learning Trigger Algorithms And Search For Higgs Boson Pair Production written by Jona Motta and has been published by Springer this book supported file pdf, txt, epub, kindle and other format this book has been release on 2025-07-27 with Science categories.
This book reports the successful optimization of the Compact Mupn Solenoid (CMS) tau trigger algorithm for the Run-3 (Phase-1) of the Large Hadron Collider (LHC) and a completely new and original design of a machine learning based tau triggering algorithm for the High Luminosity LHC (or Phase-2). A large proportion of searches at collider experiments relies on datasets collected with a dedicated tau lepton selection algorithm, particularly difficult to operate in intense hadronic environments, making the work descirbed in this book of prime importance. The second part of the book describes a major and very challenging data analysis, aiming to detect Higgs boson pair production. The book summarizes these contributions in clear, pedagogical prose while keeping an adequate and coherent balance between the technical and data analysis aspects. Machine learning techniques were used extensively throughout this research; therefore, special care has been taken to describe their core principles and application in high-energy physics, as well as potential future developments for sophisticated low-latency trigger algorithms and modern signal extraction methods.
Search For The Higgs Boson Produced In Association With Top Quarks With The Cms Detector At The Lhc
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Author : Cristina Martin Perez
language : en
Publisher: Springer Nature
Release Date : 2022-02-09
Search For The Higgs Boson Produced In Association With Top Quarks With The Cms Detector At The Lhc written by Cristina Martin Perez and has been published by Springer Nature this book supported file pdf, txt, epub, kindle and other format this book has been release on 2022-02-09 with Science categories.
In this work, the interaction between the Higgs boson and the top quark is studied with the proton-proton collisions at 13 TeV provided by the LHC at the CMS detector at CERN (Geneva). At the LHC, these particles are produced simultaneously via the associate production of the Higgs boson with one top quark (tH process) or two top quarks (ttH process). Compared to many other possible outcomes of the proton-proton interactions, these processes are very rare, as the top quark and the Higgs boson are the heaviest elementary particles known. Hence, identifying them constitutes a significant experimental challenge. A high particle selection efficiency in the CMS detector is therefore crucial. At the core of this selection stands the Level-1 (L1) trigger system, a system that filters collision events to retain only those with potential interest for physics analysis. The selection of hadronically decaying τ leptons, expected from the Higgs boson decays, is especially demanding due to the large background arising from the QCD interactions. The first part of this thesis presents the optimization of the L1 τ algorithm in Run 2 (2016-2018) and Run 3 (2022-2024) of the LHC. It includes the development of a novel trigger concept for the High-Luminosity LHC, foreseen to start in 2027 and to deliver 5 times the current instantaneous luminosity. To this end, sophisticated algorithms based on machine learning approaches are used, facilitated by the increasingly modern technology and powerful computation of the trigger system. The second part of the work presents the search of the tH and ttH processes with the subsequent decays of the Higgs boson to pairs of τ lepton, W bosons or Z bosons, making use of the data recorded during Run 2. The presence of multiple particles in the final state, along with the low cross section of the processes, makes the search an ideal use case for multivariant discriminants that enhance the selectivity of the signals and reject the overwhelming background contributions. The discriminants presented are built using state-of-the-art machine learning techniques, able to capture the correlations amongst the processes involved, as well as the so-called Matrix Element Method (MEM), which combines the theoretical description of the processes with the detector resolution effects. The level of sophistication of the methods used, along with the unprecedented amount of collision data analyzed, result in the most stringent measurements of the tH and ttH cross sections up to date.
Higgs Boson Decays Into A Pair Of Bottom Quarks
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Author : Cecilia Tosciri
language : en
Publisher: Springer Nature
Release Date : 2021-10-22
Higgs Boson Decays Into A Pair Of Bottom Quarks written by Cecilia Tosciri and has been published by Springer Nature this book supported file pdf, txt, epub, kindle and other format this book has been release on 2021-10-22 with Science categories.
The discovery in 2012 of the Higgs boson at the Large Hadron Collider (LHC) represents a milestone for the Standard Model (SM) of particle physics. Most of the SM Higgs production and decay rates have been measured at the LHC with increased precision. However, despite its experimental success, the SM is known to be only an effective manifestation of a more fundamental description of nature. The scientific research at the LHC is strongly focused on extending the SM by searching, directly or indirectly, for indications of New Physics. The extensive physics program requires increasingly advanced computational and algorithmic techniques. In the last decades, Machine Learning (ML) methods have made a prominent appearance in the field of particle physics, and promise to address many challenges faced by the LHC. This thesis presents the analysis that led to the observation of the SM Higgs boson decay into pairs of bottom quarks. The analysis exploits the production of a Higgs boson associated with a vector boson whose signatures enable efficient triggering and powerful background reduction. The main strategy to maximise the signal sensitivity is based on a multivariate approach. The analysis is performed on a dataset corresponding to a luminosity of 79.8/fb collected by the ATLAS experiment during Run-2 at a centre-of-mass energy of 13 TeV. An excess of events over the expected background is found with an observed (expected) significance of 4.9 (4.3) standard deviation. A combination with results from other \Hbb searches provides an observed (expected) significance of 5.4 (5.5). The corresponding ratio between the signal yield and the SM expectation is 1.01 +- 0.12 (stat.)+ 0.16-0.15(syst.). The 'observation' analysis was further extended to provide a finer interpretation of the V H(H → bb) signal measurement. The cross sections for the VH production times the H → bb branching ratio have been measured in exclusive regions of phase space. These measurements are used to search for possible deviations from the SM with an effective field theory approach, based on anomalous couplings of the Higgs boson. The results of the cross-section measurements, as well as the constraining of the operators that affect the couplings of the Higgs boson to the vector boson and the bottom quarks, have been documented and discussed in this thesis. This thesis also describes a novel technique for the fast simulation of the forward calorimeter response, based on similarity search methods. Such techniques constitute a branch of ML and include clustering and indexing methods that enable quick and efficient searches for vectors similar to each other. The new simulation approach provides optimal results in terms of detector resolution response and reduces the computational requirements of a standard particles simulation.
Search For Tt H Production In The H Bb Decay Channel
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Author : Marcel Rieger
language : en
Publisher: Springer Nature
Release Date : 2021-02-25
Search For Tt H Production In The H Bb Decay Channel written by Marcel Rieger and has been published by Springer Nature this book supported file pdf, txt, epub, kindle and other format this book has been release on 2021-02-25 with Science categories.
In 1964, a mechanism explaining the origin of particle masses was proposed by Robert Brout, François Englert, and Peter W. Higgs. 48 years later, in 2012, the so-called Higgs boson was discovered in proton-proton collisions recorded by experiments at the LHC. Since then, its ability to interact with quarks remained experimentally unconfirmed. This book presents a search for Higgs bosons produced in association with top quarks tt̄H in data recorded with the CMS detector in 2016. It focuses on Higgs boson decays into bottom quarks H → bb̅ and top quark pair decays involving at least one lepton. In this analysis, a multiclass classification approach using deep learning techniques was applied for the first time. In light of the dominant background contribution from tt̄ production, the developed method proved to achieve superior sensitivity with respect to existing techniques. In combination with searches in different decay channels, the presented work contributed to the first observations of tt̄H production and H → bb̅ decays.
Search For Exotic Higgs Boson Decays With Cms And Fast Machine Learning Solutions For The Lhc
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Author : Ho Fung Tsoi
language : en
Publisher:
Release Date : 2024
Search For Exotic Higgs Boson Decays With Cms And Fast Machine Learning Solutions For The Lhc written by Ho Fung Tsoi and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2024 with categories.
There exists potential for discoveries beyond the Standard Model in scalar sector, which could manifest as Higgs boson exotic decays into new light pseudoscalars. This search targets such decays, focusing on pseudoscalar masses ranging from 12 to 60 GeV, in final states where one pseudoscalar decays into two b quarks and the other into two [tau] leptons or two muons. The analysis is based on a dataset of proton-proton collisions at √s=13 TeV, collected by the CMS detector during LHC Run 2, with an integrated luminosity of 138 fb−1 Dedicated neural networks are used to distinguish between signal and background, significantly enhancing sensitivity. The results are presented as exclusion limits at 95\% confidence level on the model-independent branching ratio and are interpreted within two-Higgs doublet models augmented by a singlet. The second part of this thesis presents machine learning methods to enhance overall sensitivity in the low-latency domain for the LHC experiments. A novel machine learning-based trigger algorithm is developed, using anomaly detection to search for new physics in a model-agnostic manner as close to the raw collision data as possible. This anomaly detection trigger is sensitive to a wide range of both conventional and unconventional physics signatures and has an inference latency of $\mathcal{O}$(100) ns on an FPGA. It is deployed during Run 3 in the CMS Level-1 trigger system, which processes the first round of real-time event selection from collision data at a rate of 40 MHz. Additionally, a novel model compression method using symbolic regression is developed to accelerate machine learning inference to nanosecond speeds on FPGAs. This method demonstrates potential to significantly reduce the computational costs of machine learning algorithms while maintaining performance comparable to that of neural networks. These advancements are crucial for meeting the sensitivity and computational demands of resource-constrained environments such as the LHC experiments.
Search For Exotic Higgs Boson Decays To Merged Diphotons
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Author : Michael Andrews
language : en
Publisher: Springer Nature
Release Date : 2023-03-02
Search For Exotic Higgs Boson Decays To Merged Diphotons written by Michael Andrews and has been published by Springer Nature this book supported file pdf, txt, epub, kindle and other format this book has been release on 2023-03-02 with Science categories.
This book describes the first application at CMS of deep learning algorithms trained directly on low-level, “raw” detector data, or so-called end-to-end physics reconstruction. Growing interest in searches for exotic new physics in the CMS collaboration at the Large Hadron Collider at CERN has highlighted the need for a new generation of particle reconstruction algorithms. For many exotic physics searches, sensitivity is constrained not by the ability to extract information from particle-level data but by inefficiencies in the reconstruction of the particle-level quantities themselves. The technique achieves a breakthrough in the reconstruction of highly merged photon pairs that are completely unresolved in the CMS detector. This newfound ability is used to perform the first direct search for exotic Higgs boson decays to a pair of hypothetical light scalar particles H→aa, each subsequently decaying to a pair of highly merged photons a→yy, an analysis once thought impossible to perform. The book concludes with an outlook on potential new exotic searches made accessible by this new reconstruction paradigm.
Study Of The Higgs Boson Pair Production With Run 2 Atlas Data Using Cut Based And Machine Learning Approaches
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Author : Jia-Yu Yan
language : en
Publisher:
Release Date : 2024
Study Of The Higgs Boson Pair Production With Run 2 Atlas Data Using Cut Based And Machine Learning Approaches written by Jia-Yu Yan and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2024 with categories.
After the groundbreaking discovery of the Higgs boson, associated with the Higgs field responsible for imparting mass to other particles, by the CMS and ATLAS experiments at CERN, a promising opportunity has emerged to delve into its properties and explore new physics beyond the standard model (SM). A crucial property to be measured is the Higgs self-coupling, which directly probes the test of the Higgs potential and electroweak symmetry breaking. Higgs pair (HH) production at the Large Hadron Collider (LHC) provides a direct probe for measuring the Higgs self-coupling parameter. In this analysis, we focus on HH production through Vector Boson Fusion (VBF), which is the second-leading HH production channel. We consider the decay channel HH->bbtautau, where one tau decays leptonically and the other tau decays hadronically. The analysis uses the dataset with an integrated luminosity of 140 fb^{-1} collected by the ATLAS detector at \sqrt{s} = 13 TeV. We introduce two methods to perform the optimization, which are cut-based studies and machine learning studies, specifically using Boosted Decision Trees (BDTs), by comparing the significance and upper limits set on the cross-section. The expected upper limits by BDTs (cut-based studies), considering only statistical uncertainties, are set at the 95% confidence level on the SM HH production cross section, which is 77.7 (212.0) times the SM prediction.
Investigating The Higgs Boson Decays Into A Pair Of B And C Quarks With The Atlas Detector At The Lhc And Development Of Machine Learning Methods For Particle Flow Reconstruction
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Author : Matteo Tusoni
language : en
Publisher:
Release Date : 2023
Investigating The Higgs Boson Decays Into A Pair Of B And C Quarks With The Atlas Detector At The Lhc And Development Of Machine Learning Methods For Particle Flow Reconstruction written by Matteo Tusoni and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2023 with categories.
Search For Invisible Decays Of The Higgs Boson Produced Via Vector Boson Fusion At The Lhc With Cms Run 2 Data
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Author : Alp Akpinar
language : en
Publisher: Springer Nature
Release Date : 2024-12-23
Search For Invisible Decays Of The Higgs Boson Produced Via Vector Boson Fusion At The Lhc With Cms Run 2 Data written by Alp Akpinar and has been published by Springer Nature this book supported file pdf, txt, epub, kindle and other format this book has been release on 2024-12-23 with Science categories.
This thesis reports the latest measurements on one of the leading dark matter searches conducted by the Compact Muon Solenoid (CMS) experiment at CERN, leading to some of the most stringent constraints on hypothesized interactions between the Higgs boson and dark matter. The thesis also includes further research about the future outlook of the experiment, including exploratory research on the adaptation of deep learning models in future dark matter analyses to improve analysis sensitivity, and the design of a new type of data processing hardware to be used in the next phase of the CMS experiment.
Search For Higgs Boson Pair Production In The Semi Leptonic Bbww Channel At The Cms Experiment Using Deep Learning Techniques
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Author : Dennis Noll
language : en
Publisher:
Release Date : 2023
Search For Higgs Boson Pair Production In The Semi Leptonic Bbww Channel At The Cms Experiment Using Deep Learning Techniques written by Dennis Noll and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2023 with categories.