Abstract
The observation of long-lived particles at the LHC would reveal physics beyond the Standard Model and could account for the many open issues in our understanding of our universe. Long-lived particle signatures are well motivated and can appear in many theoretical constructs that address the Hierarchy Problem, Dark Matter, Neutrino Masses and the Baryon Asymmetry of the Universe. With the current experiments at the particle accelerators, no search strategy will be able to observe the decay of neutral long-lived particles with masses above GeV and lifetimes at the limit set by Big Bang Nucleosynthesis, cτ ∼ 107–108 m. The MATHUSLA detector concept (MAssive Timing Hodoscope for Ultra-Stable neutraL pArticles) will be presented. It can be implemented on the surface above ATLAS or CMS detectors in time for the high-luminosity LHC operations, to search for neutral long-lived particles with lifetimes up to the BBN limit. The large area of the detector allows MATHUSLA to make important contributions also to cosmic-ray physics. We will also report on the analysis of data collected by the test stand installed on the surface above the ATLAS detector, the on-going background studies, and plans for the MATHUSLA detector.
Highlights
The discovery of the Higgs boson at the LHC completed the Standard Model (SM), and focused attention on the many central features of our universe that the SM does not address: dark matter (DM), neutrino mass, particle-antiparticle asymmetry (Baryogenesis), hierarchy problem
Many BSM (Beyond the Standard Model) theoretical constructs proposed in the past few years that address these phenomena contain long-lived particles with macroscopic decay lengths limited only by Big Bang Nucleosynthesis (BBN) of about cτ 107 − 108 m
The detector signature is a hadronic jet displaced from the IP and no track connecting it to the IP
Summary
The discovery of the Higgs boson at the LHC completed the SM, and focused attention on the many central features of our universe that the SM does not address: dark matter (DM), neutrino mass, particle-antiparticle asymmetry (Baryogenesis), hierarchy problem (naturalness). The detector signature is a hadronic jet displaced from the IP and no track connecting it to the IP. The kinetic mixing of a γd results in dark photons that decay to lepton pairs giving rise to a pair of displaced lepton vertices in the detector. The hidden sector particles have no SM quantum numbers and once produced travel through the detector unabated. Once they decay to SM particles a detector signal is observed. The proposed MATHUSLA detector [11], which is a dedicated large volume, air filled detector located on the surface above and somewhat displaced from the ATLAS or CMS IPs, will be sensitive to lifetimes of 107 m with the expected integrated luminosity of High Luminosity LHC (HL-LHC)
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