Limits on inelastic dark matter from ZEPLIN-III

We present limits on the WIMP-nucleon cross section for inelastic dark matter from a reanalysis of the 2008 run of ZEPLIN-III. Cuts, notably on scintillation pulse shape and scintillation-to-ionisation ratio, give a net exposure of 63 kg day in the range 20-80 key nuclear recoil energy, in which 6 events are observed. Upper limits on signal rate are derived from the maximum empty patch in the data. Under standard halo assumptions a small region of parameter space consistent, at 99% CL, with causing the 1.17 ton yr DAMA modulation signal is allowed at 90% CL: it is in the mass range 45-60 GeV c(-2) with a minimum CL of 87%, again derived from the maximum patch. This is the tightest constraint yet presented using xenon, a target nucleus whose similarity to iodine mitigiates systematic error from the assumed halo. (C) 2010 Elsevier B.V. All rights reserved.