Searching for axionlike particles with low masses in pPb and PbPb collisions

Abstract

The production of axionlike particles (ALPs) with small masses in ultraperipheral Pb − p and Pb − Pb collisions at the LHC is investigated. The cross section and kinematical distributions associated to the diphoton final state produced in the γγ → a → γγ subprocesses are estimated considering a realistic set of kinematical cuts. A detailed analysis of the backgrounds is performed and the expected sensitivity to the ALP production is derived. Our results demonstrate that a future experimental analysis of the exclusive diphoton production for the forward rapidities probed by the LHCb detector can improve the existing exclusion limits on the ALP photon coupling in the mass range 2 GeV ≤ ma ≤ 5 GeV.