Event Title

Analysis of the Collins-Soper Angle in Contact Interaction and Large Extra Dimension Monte Carlo Data Samples

Advisor(s)

Dr. Peter Dong, Illinois Mathematics and Science Academy

Location

Room A149

Start Date

26-4-2019 10:45 AM

End Date

26-4-2019 11:00 AM

Abstract

Abstract: The Collins-Soper angle θ* is the angle between the negatively-signed lepton and the Z axis in the center of mass reference frame, calculated using Lorentz-invariant kinematic variables. In CI analyses, cosθ* is used to control the lepton angular distributions (as 1 + cosθ), as well as determine forward-backward asymmetry of the dileptons in the sample. The cosθ distribution of a sample is a crater-shaped distribution ranging from -1 to +1, with an asymmetrical shift towards +1 caused by the transverse momentum asymmetries between interacting partons.

However, the Collins-Soper calculations can give rise to significant sources of error. One such error of particular importance is the Same-Sign Electron problem. Due to systematic error inherent to event reconstruction, the measured sign of about 5-10% of electrons and positrons is flipped, leading to positrons being labelled as electrons and vice versa. The Collins-Soper Angle calculation is dependent upon proper particle identification, and as such a method for labelling the particles in case of a sign flip is needed. This study aims to determine whether there are significant differences between random assignment, high Pt trusting, low Pt trusting, and other variable-dependent methods by comparing generator-level distributions with the various models of reconstructed distributions. If there are significant differences between methods, the study will determine which method yields the most accurate results.

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Apr 26th, 10:45 AM Apr 26th, 11:00 AM

Analysis of the Collins-Soper Angle in Contact Interaction and Large Extra Dimension Monte Carlo Data Samples

Room A149

Abstract: The Collins-Soper angle θ* is the angle between the negatively-signed lepton and the Z axis in the center of mass reference frame, calculated using Lorentz-invariant kinematic variables. In CI analyses, cosθ* is used to control the lepton angular distributions (as 1 + cosθ), as well as determine forward-backward asymmetry of the dileptons in the sample. The cosθ distribution of a sample is a crater-shaped distribution ranging from -1 to +1, with an asymmetrical shift towards +1 caused by the transverse momentum asymmetries between interacting partons.

However, the Collins-Soper calculations can give rise to significant sources of error. One such error of particular importance is the Same-Sign Electron problem. Due to systematic error inherent to event reconstruction, the measured sign of about 5-10% of electrons and positrons is flipped, leading to positrons being labelled as electrons and vice versa. The Collins-Soper Angle calculation is dependent upon proper particle identification, and as such a method for labelling the particles in case of a sign flip is needed. This study aims to determine whether there are significant differences between random assignment, high Pt trusting, low Pt trusting, and other variable-dependent methods by comparing generator-level distributions with the various models of reconstructed distributions. If there are significant differences between methods, the study will determine which method yields the most accurate results.