Abstract
The phenomenology of dark sector is complicated if dark sector is charged under a confined hidden gauge group. In such kind of model, a dark parton produced at a high energy collider showers and hadronize to a cluster of dark mesons. Dark mesons then decay to visible particles and produce a jet-like signal, which is called "dark jet" in this work. Collider signal of dark jet depends on the property of dark mesons. For example, a finite lifetime of dark meson would provide displaced vertex or displaced track, thus one can use these displaced objects to tag dark jet. However if the lifetime of dark meson is collider-negligible (too short to manifest a displaced vertex), it would be difficult to distinguish a dark jet from SM 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 dark sector search at collider.
Highlights
The existence of dark matter (DM) in our Universe has been confirmed indirectly with its gravitational effects [1]
For model B, due to a weaker coupling and lower confinement scale compared to the case of model A, there is no tall spike of Cð1βÞ 1⁄4 0 at parton-level distribution, and dark meson decay pushes up Cð1βÞ only a little
The dark sector charged under a confined SUðNdÞ provides composite states and attractive phenomenologies
Summary
The existence of dark matter (DM) in our Universe has been confirmed indirectly with its gravitational effects [1]. In their scenario, a certain amount of missing energy, which comes from some stable light dark hadrons, is collimated with the dark jet, and a transverse mass of two leading jets in the final states becomes useful to discriminate the dark jets pair signal from SM background. A certain amount of missing energy, which comes from some stable light dark hadrons, is collimated with the dark jet, and a transverse mass of two leading jets in the final states becomes useful to discriminate the dark jets pair signal from SM background All these search methods become ineffective if all or most of the light dark mesons decay to SM particles promptly because in this case there are no displaced objects or missing energy inside the dark jet and the dark jet looks like a SM QCD jet. More details of our benchmark points can be found in Appendix C
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