Pileup and Underlying Event Mitigation with Iterative Constituent Subtraction

Understand

The hard-scatter processes in hadronic collisions are often largely contaminated with soft background coming from pileup in proton-proton collisions, or underlying event in heavy-ion collisions.

• This paper presents a new background subtraction method for jets and event observables (such as missing transverse energy) which is based on the previously published Constituent Subtraction algorithm.
• The new subtraction method, called Iterative Constituent Subtraction, applies event-wide implementation of Constituent Subtraction iteratively in order to fully equilibrate the background subtraction across the entire event.
• Besides documenting the new method, we provide guidelines for setting the free parameters of the subtraction algorithm.