Searching for Evidence of a 4th Generation Quark
Names: Grant Gollier, Bishop Seabury Academy, Lawrence, KS
Research Teacher Mentor: James Deane, Ottawa High School, Ottawa, KS
Research Mentor: Prof. Philip Baringer, University of Kansas, Lawrence, KS
Purpose: We are looking for evidence of a fourth generation quark which could help answer the hierarchy problem and specifically the odd discontinuity of mass.
Methods: I started by learning CERN’s ROOT data analysis framework. I used an online tutorial from Nevis Laboratories at Columbia University and help from fellow student researchers. I began by using demo files from the Nevis tutorial then proceeded to using ‘real’ files, plotting simple variables. In order to solve many of the problems I faced, I turned to both the ROOT documentation and the ROOT Talk forum. In addition to the learning curve of ROOT, I was new to C++ as well and had to learn the basic syntax and style of C++ as I went. After this introductory phase I began to look at two different decay modes for T (WbT and ZtT), plotting R, , Ht, and ptin one and two dimensional histograms. I then looked at these plots and decided upon cuts to maximize SB*k where S is the number of signal events, B is the number of background events, and k is the scale factor. This scale factor was necessary because I was only looking at one or two decay modes for as opposed to all possible decays. This scale factor accounts for the different probabilities/branching ratios.
Results: I developed multiple different scripts for processing these cuts. I looked at multiple T masses ranging from 800 GeV to 2.5 TeV. I then processed all the mass files with these cuts and passed the remaining events to plot , Ht, and pt.
Meaning to Larger Project: The hypothetical T quark offers a solution to the Hierarchy problem, which the solution to and discovery of this T would be pushing the boundaries of what is currently known in particle physics. Specifically, the cuts I was looking at would improve the quality of data I am gathering.
Future Research: As I ran short on time towards the end, I would like to spend more time analyzing the cuts I made and look for other ways to improve them. Also, following the use of these cuts more analysis would be needed to then identify the T and prove its existence.
Without the help of many of the following people this project would not have been possible
Zach Flowers, Student, University of Kansas
Emily Smith, Student, University of Kansas
Prof. Alice Bean, University of Kansas
[Link #1: http://www.nevis.columbia.edu/~seligman/root-class/