Precision Top Mass Determination at the LHC

The Standard Model (SM) is the established theory of particle physics down to distance scales as small as a thousandth of a femtometer. The frontier of high energy physics is the search for new physics beyond the SM through direct searches at the Large Hadron Collider (LHC), complimented by high precision measurements of key SM parameters. One such parameter is the mass of the top quark, the heaviest known elementary particle, about 170 times more massive than the hydrogen atom. The uncertainty in its value affects precision fits, limiting the ability to test the SM and constrain new physics. At the LHC, the most precise experimental top mass measurements are based on the method of kinematic reconstruction, which yields enhanced sensitivity to the top quark mass. We perform Pythia Monte Carlo simulations of a related observable, the boosted top jet mass spectrum, based on a newly developed factorization-based theoretical framework. We study the sensitivity of this observable to the top quark mass with over 18 million simulation events. Good agreement is found with the theoretical predictions.