PH4100 MSci Major Projects - ATLAS ttH (H-bb)

Introduction

This project is based on the analysis of simulated data of proton-proton collisions in the ATLAS particle detector at the Large Hadron Collider (LHC). The objective is to study the production of Higgs particles in association with a pair of top quarks: the so-called ttH process. Specifically the process of interest (the signal) is when the Higgs boson decays to a pair of b quarks: ttH (H-bb). The project will required the detailed analysis of simulated samples of signal events, as well as analysing all the relevant background processes. In particular ,the student will aim to develop event selection procedures to effectively separate the signal from the backgrounds. This will start with the development of a simple cut-based event selection, optimised using relevant metrics. The student can then progress this to using instead an event selection based on eg a Fisher discriminant, or more advanced multivariate methods (such as a Neural Network (NN) or a Boosted Decision Tree (BDT)).

How to connect to the linappserv computer cluster from your laptop or from a PC in the Teaching Lab

The most up-to-date instructions for this are normally on the web page of the PH4515 Statistical Data Analysis course (taught by Prof. Glen Cowan). The direct link to the instructions is here.

Troubleshooting:

• If connecting at RHUL, it seems that being connected to the CampusNet network (rather than eg eduroam) is important.
• On the Teaching Lab PCs, you may have to download PuTTY if it is not already installed. If that is the case find and download the respective the MS Installer file (*.msi) on the web. After the download is complete the file should auto-install.

Tools for the project

This is a computer-based project. You will be analysing large simulated samples of events in the ATLAS detector at the LHC. The project requires programming in C++, the use of the ROOT data analysis package and knowledge of basic Linux OS commands. Links to sources of information on these and other topics are given here.

C++ programming language

ROOT data analysis package

• User Guide for ROOT 6
• A first look at a signal ntuple: see instructions here.
• Using TSelector framework to process ntuples
• Using TLorentz four-vectors

Linux OS

emacs editor

Simulated samples

bla

-- Pedro Teixeira-Dias - 21 Oct 2019

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