104 research outputs found
Tetrahedral shape of Zr from covariant density functional theory in 3D lattice space
Covariant density functional theory is solved in 3D lattice space by
implementing the preconditioned conjugate gradient method with a filtering
function (PCG-F). It considerably improves the computational efficiency
compared to the previous inverse Hamiltonian method (IHM). This new method is
then applied to explore the tetrahedral shape of Zr in the full
deformation space. The ground state of Zr is found to have a
tetrahedral shape, but the deformations and greatly
soften the potential energy surface. This effect is analysed with the
microscopic evolution of the single-particle levels near the Fermi surface
driven by the deformation
Low-mass dark matter search results from full exposure of PandaX-I experiment
We report the results of a weakly-interacting massive particle (WIMP) dark
matter search using the full 80.1\;live-day exposure of the first stage of the
PandaX experiment (PandaX-I) located in the China Jin-Ping Underground
Laboratory. The PandaX-I detector has been optimized for detecting low-mass
WIMPs, achieving a photon detection efficiency of 9.6\%. With a fiducial liquid
xenon target mass of 54.0\,kg, no significant excess event were found above the
expected background. A profile likelihood analysis confirms our earlier finding
that the PandaX-I data disfavor all positive low-mass WIMP signals reported in
the literature under standard assumptions. A stringent bound on the low mass
WIMP is set at WIMP mass below 10\,GeV/c, demonstrating that liquid xenon
detectors can be competitive for low-mass WIMP searches.Comment: v3 as accepted by PRD. Minor update in the text in response to
referee comments. Separating Fig. 11(a) and (b) into Fig. 11 and Fig. 12.
Legend tweak in Fig. 9(b) and 9(c) as suggested by referee, as well as a
missing legend for CRESST-II legend in Fig. 12 (now Fig. 13). Same version as
submitted to PR
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