Enhancing Long-Lived Particles Searches at the LHC with Precision Timing Information

Abstract

We explore the physics potential of using precision timing information at the LHC in searches for long-lived particles (LLPs). In comparison with the light Standard Model particles, the decay products of massive LLPs arrive at detectors with time delays around nanosecond scale. We propose new strategies to take advantage of this time delay feature by using initial state radiation to timestamp the collision event and require at least one LLP to decay within the detector. This search strategy is effective for a broad range of models. In addition to outlining this general approach, we demonstrate its effectiveness with the projected reach for two benchmark scenarios: Higgs decaying into a pair of LLPs, and pair production of long-lived neutralinos in the gauge mediated supersymmetry breaking models. Our strategy increases the sensitivity to the lifetime of the LLP by two orders of magnitude or more and particularly exhibits a better behavior with a linear dependence on lifetime in the large lifetime region compared to traditional LLP searches. The timing information significantly reduces the Standard Model background and provides a powerful new dimension for LLP searches.

A sceptical analysis of quantized inertia

“…As today, no direct evidence of dark matter was detected, though many experiments such as XENON100 (Aprile et al 2012) and SuperCDMS (SuperCDMS Collaboration et al 2014) are looking for signal candidates. Some models support the idea that dark matter particles could be created at LHC and efforts in this direction are in progress (Abercrombie et al 2015;Mitsou 2015;Liu et al 2019).…”

Time-delayed electrons from Higgs decays to right-handed neutrinos

“…Previous work on this model has focused on the displaced nature of the electron and muon tracks [14]. Here we focus on the "delayed" nature of the events and follow very closely the analysis described in [26]. We first define our search criteria, describe our event simulation then we estimate backgrounds and give out results.…”

“…A main source of background is time of arrival mis-measurement due to timing resolution and pile-up due to other pp collisions that occur during the same bunch crossing. We shall model these backgrounds with gaussian distributions closely following [26] and review and apply their estimates with slight modifications below. To estimate background arising from jets we utilize the low-p T data of [44] which gives a jet cross-section of σ j = 1.6 × 10 8 pb for p T > 30 GeV.…”

“…The proposal to include a minimum ionizing particle (MIP) detector on the inner barrel and endcap regions of the electromagnetic calorimeter (Ecal) as well as planned improvements to the timing resolution of the Ecal itself at the CMS experiment promises to increase time resolution for charged particles to 30 ps at the HL-LHC [25]. The utility of this MIP/Ecal timing capability has been recently analyzed in [26] to investigate the reach of the timing capability to GMSB and higgs decays to long-lived particles where peak sensitivity is achieved at cτ = 1 m. Since a timing based analysis need not depend crucially on tracking, the time-delayed signature can arise from a signal event so long as it occurs in the main inner detector volume. Contrast this with the displaced-vertex/track searches which typically reach peak sensitivity at cτ = 1-10 cm for final state electrons.…”

“…The purpose of this paper is to analyze the physics reach of a timing based analysis of right-handed neutrino models where the higgs boson can decay to "long-lived" right-handed neutrinos which subsequently decay to final states with electrons. We shall work within the context of the type I seesaw effective theory described in [9,10] using the timing analysis techniques of [26]. This model is a well-motivated member of a much larger class of models recently reviewed in [28], in which the higgs decays to long-lived particles.…”