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 $\gamma \gamma \to a\to \gamma \gamma$ 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 $\le m_a\le$ 5 GeV.

Comments: 6 pages, 3 figures, 2 tables