U Cincinnati Abstract 2014 - Analysis of Particle Measurements from Large Hadron Collider

T. Baker, K. Debry, B. Shen,  R. Swertfeger
D. Whittington (Fairfield High School)
M. Sokoloff (University of Cincinnati)

The purpose of our research was to identify the signal and background regions in particle decay patterns and compare the measurements that to those listed in the Particle Data Group (PDG)  in order to verify the particles’ identification. We analyzed Ξ^-_{b ,} Ξ_b⁰ _, and Ω_b^-   decay channels by graphing the measurements such as invariant mass in one and two dimensional histograms while attempting to increase the clarity of the signal region by making “cuts” on the data through other measurements of the particle such as the lifetime, energy, and momentum of the particle decay. After making various cuts on the particle masses, we attempt to “fit” the peaks to a gaussian function to determine the most common masses. Comparing the masses to those on PDG, we are able to verify whether the unknown peaks are legitimate or inconclusive. By plotting Ξ^-_b mass, the histogram illustrated that the mass identified in the data (~5797 MeV) differed from that of the PDG mass (5791.1 ±2.2 MeV), alluding to a possible bias in the detector. In the Ξ_b⁰  decay channel we were able to confirm that  Ξ_b⁰  does indeed decay into Ξ^- π⁺J/Ψ by constructing invariant mass plot and isolating a strong signal at 5788 MeV, which is the mass of the parent particle Ξ_b⁰ . Furthermore, there appears to be a strong signal peak at ~3450 MeV in the Ξ_b⁰ decay; in the quest to determine this unknown signal, we compared the peak to a similar decay, that of Ξ^-_b . Alas, the the peak found at 3450 MeV was not a part of the Ξ^-_b. Further research may be done to to determine unknown peak at 3450 MeV along with the mass of Ω_b^-  particle. Additional data and effective cuts must be applied to find a more consistent mass.