Speaker
Description
Axion-like particles (ALPs) with masses between 10 MeV and 10 GeV are notoriously hard to probe. The LHC experiments are uniquely positioned to test ALPs with such masses. The dominant production mechanism of electromagnetically coupled ALPs at the LHC is vector boson fusion (VBF). For light ALPs, the photons resulting from their decay tend to overlap, appearing as a single object in the the electromagnetic calorimeter. We propose a search strategy which exploits the superior spatial resolution of the all-silicon tracker (∼10–50 μm) of the Compact Muon Solenoid experiment to target the electrons from converted photons and reconstruct the displaced decay vertex of ALPs. We present the first projected sensitivity of CMS to this signature, using alternative trigger strategies which place relaxed requirements on the features of VBF jets to enhance signal efficiency. By turning a long-standing reconstruction challenge into an experimental handle, this strategy opens a new window onto an ALP parameter space previously unexplored.