The phenomenology of the dark sector is complicated if the dark sector is charged under a confined hidden gauge group. In such a kind of model, a dark parton produced at a high-energy collider showers and hadronizes to a cluster of dark mesons. Dark mesons then decay to visible particles and produce a jetlike signal, which is called a “dark jet” in this work. Collider signal of a dark jet depend on the property of dark mesons. For example, a finite lifetime of a dark meson would provide a displaced vertex or displaced track; thus, one can use these displaced objects to tag a dark jet. However, if the lifetime of a dark meson is collider negligible (too short to manifest a displaced vertex), it would be difficult to distinguish a dark jet from standard model QCD jets. In this work, we propose a new tagging strategy to identify dark jets from QCD backgrounds. This strategy is based on jet-substructure analysis. We study various jet-substructure variables and find out variables with good discrimination ability. Our result shows that by combining multiple jet-substructure variables one could distinguish dark jets from QCD background and thus enhance the sensitivity of the dark sector search at a collider.

• Received 8 May 2019

DOI:https://doi.org/10.1103/PhysRevD.100.115009

Published by the American Physical Society under the terms of the Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article’s title, journal citation, and DOI. Funded by SCOAP³.

Published by the American Physical Society