Dive into the intricate world of particle physics with a groundbreaking exploration of b-tagging calibration at the ATLAS experiment, a cornerstone of research at the Large Hadron Collider (LHC). Unraveling the mysteries of the universe requires precision, and this book delves into the essential techniques used to identify bottom quarks, critical components in the decay of fundamental particles like the top quark and Higgs boson. Journey through the Standard Model of particle physics, the bedrock of our understanding, and witness its application in the sophisticated environment of the ATLAS detector system. Discover how physicists meticulously reconstruct particle interactions using the inner detector, calorimeters, and muon spectrometer, creating the foundation for advanced analysis. The heart of the book lies in the detailed comparison of two pivotal calibration methods: the established prel-method and the innovative sPlot technique. Explore the limitations of traditional approaches and witness the development of a continuous calibration method, a leap forward in precision. Grasp the mathematical formalism behind sPlot, understanding how it refines the calibration of b-tagging algorithms across all operating points. Through rigorous analysis of Monte Carlo simulations and real ATLAS data, the book meticulously addresses systematic uncertainties, revealing the challenges and triumphs of high-energy physics research. This is not just a theoretical exercise; it's a practical guide to enhancing the accuracy of data analysis, pushing the boundaries of our knowledge about the fundamental building blocks of the cosmos. Whether you are a seasoned researcher or a curious student, this book provides invaluable insights into the cutting-edge techniques that are shaping the future of particle physics and our understanding of the universe. Keywords: b-tagging, ATLAS experiment, Large Hadron Collider (LHC), Standard Model, bottom quark, particle physics, calibration, prel-method, sPlot technique, Monte Carlo simulation, systematic uncertainties, data analysis, detector system, data reprocessing, physics objects.
Inhaltsverzeichnis (Table of Contents)
- 1 Introduction
- 2 The Standard Model of Particle Physics
- 2.1 The Standard Model: Overview
- 2.2 Mathematical Description and Feynman Graphs
- 2.3 Bottom Quarks
- 3 The ATLAS Experiment
- 3.1 The Large Hadron Collider
- 3.2 The ATLAS Detector System
- 3.2.1 Inner Detector
- 3.2.2 Calorimeters
- 3.2.3 Muon Spectrometer
- 3.3 ATLAS Trigger System
- 3.4 ATLAS Data Reprocessing
- 3.5 Physics Objects
- 3.5.1 Primary Vertices
- 3.5.2 Tracks
- 3.5.3 Jets
- 3.5.4 Muons
- 4 b-Tagging Algorithms
- 4.1 Introduction: b-tagging Algorithms
- 4.2 Impact Parameter Based Taggers
- 4.3 Secondary Vertex Based Taggers
- 4.4 Soft Lepton Taggers
- 4.5 Advanced Taggers and Artificial Neural Networks
- 5 Calibrating b-Tagging Algorithms with the prel-Method
- 5.1 Calibration of b-Tagging Algorithms
- 5.2 The p-Method
- 5.3 Limitations of the prel-Method
- 5.4 Operating Points
- 6 Continuous b-Tagging Calibration with the sPlot Technique
- 6.1 Continuous Calibration with splot
- 6.2 sPlot: Overview
- 6.3 Log-Likelihood Fit
- 6.4 Mathematical Formalism
- 6.5 Proof and Plausibility
- 6.6 Implementation
- 7 Results
- 7.1 Applying sPlot on a Monte Carlo Simulation Sample
- 7.1.1 Monte Carlo Sample, Event Selection and Object Selection
- 7.1.2 Preliminaries
- 7.1.3 Running over Monte Carlo: Example Results
- 7.2 Toy Model Studies
- 7.2.1 Gaussian b, Exponential non-b
- 7.2.2 Gaussian b, Gaussian non-b
- 7.2.3 Gaussian b, Gaussian non-b + Correlation
- 7.2.4 Physical b, Physical non-b with downsized Correlation
- 7.3 Systematics
- 7.3.1 b-Hadron Direction
- 7.3.2 Modeling of b- and c-Production
- 7.3.3 b-Fragmentation
- 7.3.4 Muon PT-Spectrum
- 7.3.5 Modeling of b-Decays
- 7.3.6 Jet Energy
- 7.3.7 Fake Muons in b-Jets
- 7.3.8 Pileup
- 7.3.9 Semileptonic Correction
- 7.3.10 Monte Carlo Statistics
- 7.3.11 pre-Bias
- 7.3.12 Systematics: Results
- 7.4 Applying sPlot on ATLAS Data
- 7.4.1 Data Sets, Event Selection and Object Selection
- 7.4.2 Running Over Data: Example Results
- 7.1 Applying sPlot on a Monte Carlo Simulation Sample
Zielsetzung und Themenschwerpunkte (Objectives and Key Themes)
This thesis aims to explore and analyze the possibility of supplementing the existing prel-method for calibrating b-tagging algorithms at the ATLAS experiment with the sPlot technique. The goal is to achieve continuous calibration, allowing for simultaneous calibration at every operating point, rather than at select points as with the prel-method. The work investigates the effectiveness and limitations of this combined approach.
- Calibration of b-tagging algorithms at the ATLAS experiment.
- Comparison of the prel-method and the sPlot technique for b-tagging calibration.
- Development and implementation of a continuous calibration method.
- Analysis of systematic uncertainties affecting the calibration.
- Application of the improved method to both Monte Carlo simulations and real ATLAS data.
Zusammenfassung der Kapitel (Chapter Summaries)
1 Introduction: This chapter introduces the context of the research, highlighting the importance of b-tagging algorithms in analyzing data from the Large Hadron Collider (LHC) at CERN. It emphasizes the role of b-tagging in identifying particles containing bottom quarks, crucial for various physics analyses, such as top quark and Higgs boson decay studies. The chapter then outlines the thesis's structure and its objectives, focusing on improving the calibration of b-tagging algorithms through a combined approach using the prel-method and the sPlot technique.
2 The Standard Model of Particle Physics: This chapter provides a concise overview of the Standard Model of particle physics, serving as a theoretical foundation for the subsequent analysis of experimental data. It includes a description of the Standard Model's mathematical framework and its representation using Feynman diagrams. Particular focus is given to bottom quarks, their properties, and their importance in the context of b-tagging.
3 The ATLAS Experiment: This chapter describes the experimental setup, focusing on the Large Hadron Collider (LHC) and the ATLAS detector system. It details the detector components—the inner detector, calorimeters, and muon spectrometer—and explains their function in recording and reconstructing particle interactions. The ATLAS trigger system and data reprocessing are also described. Finally, the reconstruction of relevant physics objects like primary vertices, tracks, jets, and muons, is presented as these objects are directly used in the b-tagging algorithms.
4 b-Tagging Algorithms: This chapter introduces various b-tagging algorithms, focusing on those utilized in this thesis. It details the different approaches used to identify b-jets, including those based on impact parameters, secondary vertices, and soft leptons. The chapter also provides information on more advanced taggers and the use of artificial neural networks in b-tagging.
5 Calibrating b-Tagging Algorithms with the prel-Method: This chapter describes the current prel-method used for b-tagging algorithm calibration, explaining its functionality and limitations. It lays the groundwork for the introduction of the sPlot technique as a complementary method. The significance of selecting specific operating points for calibration is also discussed.
6 Continuous b-Tagging Calibration with the sPlot Technique: This chapter introduces the sPlot technique as a method to improve upon the prel-method. It provides an overview of the technique, detailing its mathematical formalism and implementation. The chapter establishes the theoretical foundations and demonstrates the plausibility of achieving a continuous calibration of b-tagging algorithms using this method.
Schlüsselwörter (Keywords)
b-tagging, ATLAS experiment, Large Hadron Collider (LHC), Standard Model, bottom quark, particle physics, calibration, prel-method, sPlot technique, Monte Carlo simulation, systematic uncertainties, data analysis.
Häufig gestellte Fragen
Was ist das Thema des Dokuments?
Das Dokument ist eine umfassende Sprachvorschau, die Titel, Inhaltsverzeichnis, Ziele und Schwerpunktthemen, Kapitelzusammenfassungen und Schlüsselwörter umfasst.
Was enthält das Inhaltsverzeichnis?
Das Inhaltsverzeichnis umfasst: Einführung, Das Standardmodell der Teilchenphysik, Das ATLAS-Experiment, b-Tagging-Algorithmen, Kalibrierung von b-Tagging-Algorithmen mit der prel-Methode, Kontinuierliche b-Tagging-Kalibrierung mit der sPlot-Technik und Ergebnisse.
Welche Hauptthemen werden in diesem Dokument behandelt?
Die Hauptthemen sind: Kalibrierung von b-Tagging-Algorithmen am ATLAS-Experiment, Vergleich der prel-Methode und der sPlot-Technik zur b-Tagging-Kalibrierung, Entwicklung und Implementierung einer kontinuierlichen Kalibrierungsmethode, Analyse systematischer Unsicherheiten, und Anwendung der verbesserten Methode auf Monte-Carlo-Simulationen und reale ATLAS-Daten.
Was ist das Ziel der Arbeit bezüglich b-Tagging-Algorithmen?
Ziel der Arbeit ist es, die Möglichkeit zu untersuchen und zu analysieren, die bestehende prel-Methode zur Kalibrierung von b-Tagging-Algorithmen am ATLAS-Experiment durch die sPlot-Technik zu ergänzen, um eine kontinuierliche Kalibrierung zu erreichen.
Was sind die Schlüsselwörter des Dokuments?
Die Schlüsselwörter sind: b-Tagging, ATLAS-Experiment, Large Hadron Collider (LHC), Standardmodell, Bottom-Quark, Teilchenphysik, Kalibrierung, prel-Methode, sPlot-Technik, Monte-Carlo-Simulation, systematische Unsicherheiten, Datenanalyse.
Was beschreibt Kapitel 3?
Kapitel 3 beschreibt das ATLAS-Experiment, einschließlich des Large Hadron Collider (LHC) und des ATLAS-Detektorsystems. Es werden die Detektorkomponenten, das Triggersystem und die Datenaufbereitung detailliert beschrieben. Ebenso wird die Rekonstruktion relevanter physikalischer Objekte wie primäre Vertices, Tracks, Jets und Myonen vorgestellt.
Was wird in Kapitel 4 behandelt?
Kapitel 4 stellt verschiedene b-Tagging-Algorithmen vor, wobei der Schwerpunkt auf den in dieser Arbeit verwendeten liegt. Es werden verschiedene Ansätze zur Identifizierung von b-Jets beschrieben, einschließlich solcher, die auf Stoßparametern, sekundären Vertices und Soft-Leptonen basieren. Außerdem werden Informationen zu fortgeschritteneren Taggern und der Verwendung künstlicher neuronaler Netze beim b-Tagging gegeben.
Was wird in Kapitel 5 erläutert?
Kapitel 5 beschreibt die aktuelle prel-Methode zur Kalibrierung von b-Tagging-Algorithmen und erläutert deren Funktionalität und Einschränkungen. Es legt den Grundstein für die Einführung der sPlot-Technik als ergänzende Methode. Die Bedeutung der Auswahl spezifischer Betriebspunkte für die Kalibrierung wird ebenfalls erörtert.
Was wird in Kapitel 6 erläutert?
Kapitel 6 stellt die sPlot-Technik als eine Methode zur Verbesserung der prel-Methode vor. Es bietet einen Überblick über die Technik und erläutert deren mathematischen Formalismus und Implementierung. Das Kapitel legt die theoretischen Grundlagen und demonstriert die Plausibilität der Erzielung einer kontinuierlichen Kalibrierung von b-Tagging-Algorithmen mit dieser Methode.
- Quote paper
- Timea Krones (Author), 2013, Continuous Calibration of b-tagging algorithms with pTrel and sPlot, Munich, GRIN Verlag, https://www.grin.com/document/1191333
