Mass limits for fourth generation sequential neutrinos from dark matter experiments

Abstract

Current mass limits for fourth generation sequential neutrinos come from dark matter experiments assuming $\rho_{DM}=0.2-0.8$ g/ cm$^3$. We show that the latest results from the CDMS II experiment exclude Dirac neutrinos with masses below 500 GeV assuming only that they are produced as expected by the Big Bang model and clump in the same manner as baryons. We also show the next generation of nuclear recoil experiments will be sensitive to fourth generation Majorana nuetrinos. Finally, we consider the case in which the neutrino interacts with the nucleus via the exchange of a Higgs boson.