Low-threshold analysis of CDMS shallow-site data

Data taken during the final shallow-site run of the first tower of the Cryogenic Dark Matter Search (CDMS II) detectors have been reanalyzed with improved sensitivity to small energy depositions. Four ~224 g germanium and two ~105 g silicon detectors were operated at the Stanford Underground Facility (SUF) between December 2001 and June 2002, yielding 118 live days of raw exposure. Three of the germanium and both silicon detectors were analyzed with a new low-threshold technique, making it possible to lower the germanium and silicon analysis thresholds down to the actual trigger thresholds of ~1 and ~2 keV, respectively. Limits on the spin-independent cross section for weakly interacting massive particles (WIMPs) to elastically scatter from nuclei based on these data exclude interesting parameter space for WIMPs with masses below 9 GeV/c^2. Under standard halo assumptions, these data partially exclude parameter space favored by interpretations of the DAMA/LIBRA and CoGeNT experiments’ data as WIMP signals, and exclude new parameter space for WIMP masses between 3 and 4 GeV/c^2

Search for inelastic dark matter with the CDMS II experiment

Results are presented from a reanalysis of the entire five-tower data set acquired with the Cryogenic Dark Matter Search (CDMS II) experiment at the Soudan Underground Laboratory, with an exposure of 969 kg-days. The analysis window was extended to a recoil energy of 150 keV, and an improved surface-event background-rejection cut was defined to increase the sensitivity of the experiment to the inelastic dark matter (iDM) model. Three dark matter candidates were found between 25 keV and 150 keV. The probability to observe three or more background events in this energy range is 11%. Because of the occurrence of these events, the constraints on the iDM parameter space are slightly less stringent than those from our previous analysis, which used an energy window of 10–100 keV. © 2011 American Physical Societ

Neutrino Coherent Scattering Rates at Direct Dark Matter Detectors

Neutrino-induced recoil events may constitute a background to direct dark matter searches, particularly for those detectors that strive to reach the ton-scale and beyond. This paper discusses the expected neutrino-induced background spectrum due to several of the most important sources, including solar, atmospheric, and diffuse supernova neutrinos. The largest rate arises from $^8$B produced solar neutrinos, providing upwards of $\sim 10^3$ events per ton-year over all recoil energies for the heaviest nuclear targets. However the majority of these $^8$B events are expected to be below the recoil threshold of modern detectors. The remaining neutrino sources are found to constitute a background to the WIMP-induced recoil rate only if the WIMP-nucleon cross section is less than $10^{-12}$ pb. Finally the sensitivity to diffuse supernova neutrino flux for non-electron neutrino flavors is discussed, and projected flux limits are compared with existing flux limits

DAMA detection claim is still compatible with all other DM searches

We show that the annual modulation signal observed by DAMA can be reconciled with all other negative results from dark matter searches with a conventional halo model for particle masses around 5 to 9 GeV. We also show which particular dark matter stream could produce the DAMA signal.Comment: Talk given at TAUP2005, Sept. 10-14 2005, Zaragoza (Spain). 3 pages, 4 figure

Direct detection of supersymmetric dark matter- Theoretical rates for transitions to excited states

The recent WMAP data have confirmed that exotic dark matter together with the vacuum energy (cosmological constant) dominate in the flat Universe. Supersymmetry provides a natural dark matter candidate, the lightest supersymmetric particle (LSP). Thus the direct dark matter detection is central to particle physics and cosmology. Most of the research on this issue has hitherto focused on the detection of the recoiling nucleus. In this paper we study transitions to the excited states, focusing on the first excited state at 50 keV of Iodine A=127. We find that the transition rate to this excited state is about 10 percent of the transition to the ground state. So, in principle, the extra signature of the gammai ray following its de-excitation can be exploited experimentally.Comment: LaTex, 13 pages, 3 postscript figures, 1 table, to appear in IJMP

`Natural Masslessness Conservation' for neutrinos in two Higgs-doublet models

We present a model which supplements the Standard Electroweak Model with three right-handed neutrinos and one extra scalar doublet which does not develop a vacuum expectation value. With the aid of a discrete symmetry the neutrinos are kept strictly massless. This model has several interesting features. It has unsuppressed lepton flavour violating processes, in particular $\mu \rightarrow e \gamma$, hinting at the possibility that these may soon be within experimental reach. The $Z$ and $W$ interactions become non-diagonal at one loop level. In particular, a non-trivial leptonic mixing matrix is seen to arise from the clash between the charged gauge boson and the charged scalar interactions.Comment: (Latex file, 12 pages. Two figures available upon request). CMU-preprin

Single Neutralino production at CERN LHC

The common belief that the lightest supersymmetric particle (LSP) might be a neutralino, providing also the main Dark Matter (DM) component, calls for maximal detail in the study of the neutralino properties. Motivated by this, we consider the direct production of a single neutralino \tchi^0_i at a high/energy hadron collider, focusing on the \tchi^0_1 and \tchi^0_2 cases. At Born level, the relevant subprocesses are q\bar q\to \tchi^0_i \tilde g, g q\to \tchi^0_i \tilde q_{L,R} and q\bar q'\to \tchi^0_i\tchi^\pm_j; while at 1-loop, apart from radiative corrections to these processes, we consider also gg\to \tchi^0_i\tilde{g}, for which a numerical code named PLATONgluino is released. The relative importance of these channels turns out to be extremely model dependent. Combining these results with an analogous study of the direct \tchi^0_i\tchi^0_j pair production, should help in testing the SUSY models and the Dark Matter assignment.Comment: 22 pages and 12 figures; version to appear in Phys.Rev.