  We discuss the possibility of identifying invisible objects (e.g. dark
matter) via missing mass in Central Exclusive Processes; that is, in events
where only forward protons are detected at the LHC. We show that the signal
must have a cross section greater than 0.25 fb in order that it can be
detected. We estimate the huge background caused by soft proton dissociation
and evaluate the requirements of the detector `veto' system needed to
sufficiently suppress these events. In addition, we discuss the related process
leading to the possible identification of the particles from the so-called
`compressed-mass Beyond the Standard Model (BSM)' scenarios. In this case the
background is not so severe.
