Jet timing

Abstract

The measurement of the arrival time of a particle, such as a lepton, a photon, or a pion, reaching the detector provides valuable information. A similar measurement for a hadronic final state, however, is much more challenging as one has to extract the relevant information from a collection of particles. In this paper, we explore various possibilities in defining the time of a jet through the measurable arrival times of the jet constituents. We find that a definition of jet time based on a transverse momentum weighted sum of the times of the constituents has the best performance. For prompt jets, the performance depends on the jet trajectory. For delayed jets, the performance depends on the trajectory of the jet, the trajectory of the mother particle, and the location of the displaced vertex. Compared to the next-best-performing jet time definition, the transverse momentum weighted sum has roughly a factor of ten times better jet time resolution. We give a detailed discussion of the relevant effects and characterize the full geometrical dependence of the performance. These results highlight the critical importance of using a proper definition of jet time with its corresponding detector-dependent calibration and the exciting possibility of deepening our understanding of jets in the time domain.

Report of the Topical Group on Physics Beyond the Standard Model at Energy Frontier for Snowmass 2021

“…In addition, ATLAS plans to focus on the challenging forward region with their High-Granularity Timing Detector [361], which may also have physics potential for LLPs. Generally, the usage of precision timing information and correlating them with different subdetectors could enhanced sensitivities to a broad class of long-lived particles signature [358,360,362].…”

Jets and Jet Substructure at Future Colliders

“…Unconventional signatures can include cases where jets are composed of leptons and hadrons, only leptons, only photons, hadrons and missing transverse energy etc. In addition to the jet kinematics and JSS, the jet timing [195][196][197] information and other information can be used for classification. Examples include jets containing one or more hard leptons [198][199][200][201][202], displaced vertices [200], hard photons [203,204], or significant missing transverse momentum [205][206][207][208].…”

“…Several BSM predictions (e.g., supersymmetry (SUSY) with gauge-mediated SUSY breaking [222][223][224][225], hidden valley models [226], a Higgs boson decaying to glueballs where the Higgs boson is the portal to a dark QCD sector whose lightest states are the long-lived glueballs) [227,228] lead to the unusual signature of non prompt or delayed jets which are sensitive to the proper measurement of jet timing [197]. These non prompt or delayed jets are usually modeled to be produced by the displaced decays of the heavy long-lived particles in BSM.…”

Tripling down on the W boson mass

“…Depending on the initial state, one may also expect prompt off-shell W bosons. These prompt jets/leptons could be used to tag the events provided that the intrinsic jet time spread is sufficiently low [123]. It should also be noted that recently ATLAS found am anomalously large ionization energy loss [124].…”