We report on a search for low-energy (E < 20 keV) WIMP-induced nuclear recoils using data collected in 2009 − 2010 by EDELWEISS from four germanium detectors equipped with thermal sensors and an electrode design (ID) which allows to efficiently reject several sources of background. The data indicate no evidence for an exponential distribution of low-energy nuclear recoils that could be attributed to WIMP elastic scattering after an exposure of 113 kg·d. For WIMPs of mass 10 GeV, the observation of one event in the WIMP search region results in a 90% CL limit of 1.0 × 10 −5 pb on the spin-independent WIMP-nucleon scattering cross-section, which constrains the parameter space associated with the findings reported by the CoGeNT, DAMA and CRESST experiments.
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 Aγ < 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.
In LaAlO 3 /SrTiO 3 heterostructures, a gate tunable superconducting electron gas is confined in a quantum well at the interface between two insulating oxides. Remarkably, the gas coexists with both magnetism and strong Rashba spin-orbit coupling. However, both the origin of superconductivity and the nature of the transition to the normal state over the whole doping range remain elusive. Here we use resonant microwave transport to extract the superfluid stiffness and the superconducting gap energy of the LaAlO 3 /SrTiO 3 interface as a function of carrier density. We show that the superconducting phase diagram of this system is controlled by the competition between electron pairing and phase coherence. The analysis of the superfluid density reveals that only a very small fraction of the electrons condenses into the superconducting state. We propose that this corresponds to the weak filling of highenergy d xz /d yz bands in the quantum well, more apt to host superconductivity.
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