Axion searches with the EDELWEISS-II experiment

Abstract

We present new constraints on the couplings of axions and more generic axionlike particles using data from the EDELWEISS-II experiment. The EDELWEISS experiment, located at the Underground Laboratory of Modane, primarily aims at the direct detection of WIMPs using germanium bolometers. It is also sensitive to the low-energy electron recoils that would be induced by solar or dark matter axions. Using a total exposure of up to 448 kg.d, we searched for axion-induced electron recoils down to 2.5 keV within four scenarios involving different hypotheses on the origin and couplings of axions. We set a 95 % CL limit on the coupling to photons g A < 2.13 10 -9 GeV -1 in a mass range not fully covered by axion helioscopes. We also constrain the coupling to electrons, g Ae < 2.56 10 -11 , similar to the more indirect solar neutrino bound. Finally we place a limit on g Ae g eff AN < 4.70 10 -17 , where g eff AN is the effective axion-nucleon coupling for 57 Fe. Combining these results we fully exclude the mass range 0.91 eV < m A < 80 keV for DFSZ axions and 5.73 eV < m A < 40 keV for KSVZ axions.