Critical comment on the recent microscopic black hole search at the LHC

Recently the CMS Collaboration at the LHC reported 'the first direct limit on black hole production at a particle accelerator' using a data sample corresponding to an integrated luminosity of 35 pb-1 of pp collision at a center of mass energy of 7 TeV (Khachatryan et al., 2011) . Even though the result has a strong impact on future searches, the interpretation lacks enough theoretical support. In this Letter, we show that the parameter range which was considered by the CMS Collaboration is actually out of the validity range of semi-classical black hole picture so that the Monte Carlo simulation result which was crucially used in the analysis still needs further solid scientific basis.