We review the confused situation concerning evidence for low-mass WIMPs. In the past one half year there have been new results concerning the existence of WIMPs at low mass including the new XENON 100, 100-day data, additional CDMS results, the publication of annual variation data from LVD and Borexino and new CoGeNT data. Along with the S2 analyses of the XENON 10 data we provide an overview of this situation. We discuss new results from 2011 here. We also discuss the origin of annual variations of signals in underground laboratories.
This article is meant to be an update of recent experimental results. It is not a critical comparison of the claims of various experimental groups. Such critiques are made in public conferences and meetings. There is currently an intense discussion being carried out about the low mass WIMP region with many different viewpoints. We have little to say about this situation except that the scientific method usually insures the correct results will eventually surface.
The suggesting of other sources for season variation in underground laboratory results is a major contribution to the debate. The crux of the matter is that:
The authors of CoGeNT, CRESST, and DAMA indicate that the three experiments show the evidence for low-mass WIMPs. However the DAMA results are excluded by two CDMS experiments. Therefore three to four independent experiments exclude the low WIMP mass hypothesis.
Nothing indicates the limitations of self-estimated error bars more than conflicting contemporaneous experiments conducted by groups of professional physicists that show the existence or non-existence of the same thing to considerable statistical significance.
My prediction is that the CoGeNT, CRESST and DAMA experimental evidence for the low WIMP mass hypothesis, which is not necessarily even entirely consistent between the experiments, will ultimately be found to have been premature and attributed to other causes in the background that were not accounted for in the initial analysis. But, I'd be delighted to be wrong and see "new physics" discovered instead.
See also more discussion here.