PH4100 Major Project

Information regarding 4th year projects based on ATLFAST ntuples. (See my Log Book 11, page 10, for useful notes for the project kick-off meetings. See also the .../teaching/ph4100/ directory in my laptop.)

Introduction

In this project the student will be studying the feasibility of the Higgs search with the ATLAS detector at the Large Hadron Collider (LHC), in a given Higgs search channel or channels.

The student is advised to read about the LHC, its physics programme, and past and ongoing searches for the Higgs boson. Select some papers from this list of overview papers.

The fractions of signal and background events that will contribute to a particular final state (eg, tt-->bqq blv) should be calculated using this table of Branching Ratios (BR) (from PYTHIA 6.323). It contains useful data on the BRs of Standard Model particles such as W and Z bosons, tau leptons, and more. Higgs boson production cross-sections and decay branching fractions can be obtained from the ATLAS note

Higgs production cross-sections and branching ratios for the ATLAS Higgs working group, ATL-COM-PHYS-2007-024

ATLFAST ntuples

(Information on the simulated samples can be found in my Log Book 11, page 23.)

All of the Monte Carlo (MC) event samples include simulation of the underlying event. PYTHIA 6.xxx was used to generate the events. The fast simulation of the detector response was carried out with ATLFAST 15.8.0, and the ATLFAST ntuples include Run No and Event No information.

Information about which processes have been simulated, the respective sample sizes and cross-sections, and the location of the ntuples is available in this file.

More information: the ATLFAST simulation program.

Analysing the data

The simulated data ntuples can be analysed with the help of an object-oriented data analysis package provided by CERN, called ROOT. This tutorial covers the basic usage of ROOT for the purpose of running analysis tools on ATLAS data.

The actual data analysis code will be written by the student, in C++. I will provide you with template code to read in an ntuple, book some histograms, apply some event selection cuts, fill in the histograms and print them to file. Use of TLorentzVectors is also demonstrated (more details available here). (Files run_analysis.C, analysis.C and analysis.h in the ATLAS/analysis/FilesForY4ProjectStudents/ directory in linappserv.)

-- PedroTeixeiraDias - 13 Jun 2011