GERDA Directly Contradicts Heidelberg-Moscow Experiment

The Heidelberg-Moscow experiment is the outlier in studies of neutrinoless double beta decay which it claims to have discovered that all other experimental searches for it have not replicated.  One argument to support its positive detection has been that its experiment used radioactive isotypes of Germanium while other searches used other radioactive isotypes that might been less prone to revealing neutrinoless double beta decay.

The GERDA experiment, however, exactly replicated the Heidelberg-Moscow experiment's beta decay source and has now ruled out the possibility that the Heideberg-Moscow experiment's observations are correct at more than a 90% confidence level (specifically, GERDA ruled out decays of 2.1*10^25 years at more than 90% confidence and the H-M experiment's result was 1.2*10^25 years).  In the next few years, the neutrinoless double beta decay rate that GERDA can exclude will increase by a factor of ten as more data are collected and its methods are refined with experience.  This would give GERDA the experimental power to definitively rule out the Heidelberg-Moscow experiment's detection result directly at a much higher sigma level.  It is increasingly clear that the Heidelberg-Moscow experiment result is a false positive that is a consequence of systemic error not properly accounted for by the people conducting the experiment.

While GERDA merely confirms what several other experiments has already concluded, the fact that it does so with an almost identical experimental setup rules out a variety of theoretical arguments that could attempt to patch up the differences between their results and other studies conducted with different isotypes.

Also, GERDA, like every neutrinoless double beta decay experiment, also adds to the cumulative data set of worldwide neutrinoless double beta decay searches every conducted which can be aggregated in a meta-analysis to provide a combined double beta decay half-life exclusion range that is greater than that of any of the contributing studies individually.  Ultimately, the exclusion range is a function of nuclei seconds without an observed neutrinoless double beta decay in circumstances where it could be detected if there was one.  Every new experiment makes that number a little larger and hence adds to the exclusion range.

The combined exclusion from a couple of different experiments as of March 2013 was a minimum half-life of the decay longer 3.4*10^25 years.  The new GERDA data pushed the combined threshold higher than that, although I lack the ability without really lengthy analysis and research to combined the data correctly.

The de facto exclusion from all experiments combined done to date is probably at least a factor of ten longer than the longest exclusion range of any individual experiment already conducted by itself, which is coming every closer to ruling out a significant Majorana component to the absolute neutrino masses.  The March 2013 result implied a maximum Majorana neutrino mass of 120-250 meV.  The minimum neutrino mass in a normal neutrino mass hierarchy based on neutrino mass state differences is about 60 meV and is about 110 meV in an inverted neutrino mass hierarchy.  If the neutrinoless double beta decay rate half life is increased to a level that implies a maximum Majorana neutrino mass of less than about 110 meV, completely Majorana mass neutrinos with an inverted hierarchy are excluded (back of napkin this is about 7*10^25 years minimum half-life if my understanding of the relationship between half-life and Majorana neutrino mass is approximately correct).  If it is increased to a level that implies a maximum Majorana neutrino mass of less than 60 meV, there must be at least some Dirac neutrino mass (back of napkin this is about 1.2*10^26 years minimum half-life).  Thus, a fairly reliable answer to the question of whether neutrinos have Dirac mass or not, can realistically be attained by the year 2020 or so, maybe earlier with thoughtful meta-analysis of combined results from multiple experiments that are currently underway.

This also continues to disfavor strongly a large class of SUSY theories with R-parity violation and heavy superpartners (which other research is forcing the SUSY parameter space into).