#### Event Title

Calculating the Collins-Soper Angle of Simulated Particle Physics Data

#### Session Number

Project ID: PHYS 04

#### Advisor(s)

Dr. Peter Dong; llinois Mathematics and Science Academy

Dr. Leonard Spiegel; Fermilab

#### Discipline

Physical Science

#### Start Date

22-4-2020 8:30 AM

#### End Date

22-4-2020 8:45 AM

#### Abstract

The Collins-Soper angle, referred to as cos(ϴ*), measures the angle of the negatively charged lepton in dilepton events with respect to the beam axis. When we reconstruct events that are simulated using Monte Carlo, we sometimes encounter situations where both leptons in the dilepton pair share the same sign. This sign error originates from our particle detector because the curvature of high-energy electrons is hard to measure. However, the calculation of cos(ϴ*) requires the leptons to have opposite signs. Rather than randomly assigning charges to the lepton and antilepton, we determined that we should trust the sign of the particle with the lower pseudorapidity. Instead of guessing correctly half of the time, our new strategy identified the negatively charged leptons at a 70% success rate. Using the modular framework that we built to analyze cos(ϴ*), we have continued to investigate the behavior of our simulated data by looking at acceptance, migration, and mass resolution.

Calculating the Collins-Soper Angle of Simulated Particle Physics Data

The Collins-Soper angle, referred to as cos(ϴ*), measures the angle of the negatively charged lepton in dilepton events with respect to the beam axis. When we reconstruct events that are simulated using Monte Carlo, we sometimes encounter situations where both leptons in the dilepton pair share the same sign. This sign error originates from our particle detector because the curvature of high-energy electrons is hard to measure. However, the calculation of cos(ϴ*) requires the leptons to have opposite signs. Rather than randomly assigning charges to the lepton and antilepton, we determined that we should trust the sign of the particle with the lower pseudorapidity. Instead of guessing correctly half of the time, our new strategy identified the negatively charged leptons at a 70% success rate. Using the modular framework that we built to analyze cos(ϴ*), we have continued to investigate the behavior of our simulated data by looking at acceptance, migration, and mass resolution.