Abstract

An analysis of dimuon data was done using a graph of events vs. mass of dimuon data.  Two different masses corresponded to two different particles which were identified as the J/Psi and Upsilon particles.

Introduction

We obtained data from the CMS e-lab site because we wanted to analyze collision data that produced two muons. From this data we hoped to identify any primary particles that would have decayed into two muons.  These particles could be identified based on a high number of events at one or more particular masses.

Procedures

1.  We selected the dimuon data set from LHC 2011 using the muon event.

2.  We plotted events that had 2 global muons of opposite charges. (Global muons are detected in the silicon tracker and the muon chamber.  (Fig. 1)

3.  The data plotted had a bin width of 1 GeV/c². (Fig. 2)

4.  A significant region was identified from 0-20 GeV/c².  Bin width was adjusted to .01 to improve resolution. (Fig. 3)

Results

There was a significant number of events corresponding to a mass of 3.09 GeV/c² and a lesser, but still significant number, of events corresponding to 9.45 GeV/c².  There were approximately 610 3.09 GeV/c² events and approximately 70 9.45 GeV/c² events.  

Discussions & Conclusions

From the Standard Model we determined that the 3.09 events were J/Psi particles and the 9.45 events were Upsilon particles.  The J/Psi spike on the graph was much taller and narrower indicating the much higher number of events relative to the Upsilon spike, which was shorter and wider. 

Further studies could be done to determine why the two spikes had such different qualities.

Bibliography

CMS e-Lab

Matthew Jones