Axion searches with the EDELWEISS-II experiment

We present new constraints on the couplings of axions and more generic axion-like 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_Aγ < 2.15 × 10^-9 GeV^-1 in a mass range not fully covered by axion helioscopes. We also constrain the coupling to electrons, g_Ae < 2.59 × 10^-11, similar to the more indirect solar neutrino bound. Finally we place a limit on g_Ae × g_AN^eff < 4.82 × 10^-17, where g_AN^eff is the effective axion-nucleon coupling for ⁵⁷Fe. Combining these results we fully exclude the mass range 0.92 eV < m_A < 80 keV for DFSZ axions and 5.78 eV < m_A < 40 keV for KSVZ axions.