Identification of RR Lyrae stars in multiband, sparsely-sampled data from the Dark Energy Survey using template fitting and Random Forest classification

International audienceMany studies have shown that RR Lyrae variable stars (RRL) are powerful stellar tracers of Galactic halo structure and satellite galaxies. The Dark Energy Survey (DES), with its deep and wide coverage (g ~ 23.5 mag in a single exposure; over 5000 deg2) provides a rich opportunity to search for substructures out to the edge of the Milky Way halo. However, the sparse and unevenly sampled multiband light curves from the DES wide-field survey (a median of four observations in each of grizY over the first three years) pose a challenge for traditional techniques used to detect RRL. We present an empirically motivated and computationally efficient template-fitting method to identify these variable stars using three years of DES data. When tested on DES light curves of previously classified objects in SDSS stripe 82, our algorithm recovers 89% of RRL periods to within 1% of their true value with 85% purity and 76% completeness. Using this method, we identify 5783 RRL candidates, ~28% of which are previously undiscovered. This method will be useful for identifying RRL in other sparse multiband data sets

Updated search for the standard model Higgs boson in events with jets and missing transverse energy using the full CDF data set

We present an updated search for the Higgs boson produced in association with a vector boson in the final state with missing transverse energy and two jets. We use the full CDF data set corresponding to an integrated luminosity of 9.45  fb<sup>−1</sup> at a proton-antiproton center-of-mass energy of √<span style="text-decoration:overline">s</span>=1.96  TeV. New to this analysis is the inclusion of a b-jet identification algorithm specifically optimized for H→bb¯ searches. Across the Higgs boson mass range 90≤mH≤150  GeV/c2, the expected 95% credibility level upper limits on the VH production cross section times the H→bb¯ branching fraction are improved by an average of 14% relative to the previous analysis. At a Higgs boson mass of 125  GeV/c2, the observed (expected) limit is 3.06 (3.33) times the standard model prediction, corresponding to one of the most sensitive searches to date in this final state