Photon isolation and jet substructure

• Main Authors: Hall, Zachary (Contributor), Thaler, Jesse (Contributor)
• Other Authors: Massachusetts Institute of Technology. Center for Theoretical Physics (Contributor), Massachusetts Institute of Technology. Department of Physics (Contributor)
• Format: Article
• Language: English
• Published: Springer Berlin Heidelberg, 2018-10-01T17:47:29Z.
• Subjects: Article
• Online Access: Get fulltext

We introduce soft drop isolation, a new photon isolation criterion inspired by jet substructure techniques. Soft drop isolation is collinear safe and is equivalent to Frixione isolation at leading non-trivial order in the small R limit. However, soft drop isolation has the interesting feature of being democratic, meaning that photons can be treated equivalently to hadrons for initial jet clustering. Taking advantage of this democratic property, we define an isolated photon subjet: a photon that is not isolated from its parent jet but is isolated within its parent subjet after soft drop declustering. The kinematics of this isolated photon subjet can be used to expose the QED splitting function, in which a quark radiates a photon, and we verify this behavior using both a parton shower generator and a perturbative calculation in the collinear limit. Keywords: Jets, QCD Phenomenology
United States. Department of Energy. High Energy Physics Division (Grant DE-SC0012567)
Massachusetts Institute of Technology. Undergraduate Research Opportunities Program