90 research outputs found
Can tonne-scale direct detection experiments discover nuclear dark matter?
Models of nuclear dark matter propose that the dark sector contains large
composite states consisting of dark nucleons in analogy to Standard Model
nuclei. We examine the direct detection phenomenology of a particular class of
nuclear dark matter model at the current generation of tonne-scale liquid noble
experiments, in particular DEAP-3600 and XENON1T. In our chosen nuclear dark
matter scenario distinctive features arise in the recoil energy spectra due to
the non-point-like nature of the composite dark matter state. We calculate the
number of events required to distinguish these spectra from those of a standard
point-like WIMP state with a decaying exponential recoil spectrum. In the most
favourable regions of nuclear dark matter parameter space, we find that a few
tens of events are needed to distinguish nuclear dark matter from WIMPs at the
level in a single experiment. Given the total exposure time of
DEAP-3600 and XENON1T we find that at best a distinction is
possible by these experiments individually, while sensitivity is
reached for a range of parameters by the combination of the two experiments. We
show that future upgrades of these experiments have potential to distinguish a
large range of nuclear dark matter models from that of a WIMP at greater than
.Comment: 23 pages, 7 multipanel figure
A study of charged kappa in
Based on events collected by BESII, the decay
is studied. In the invariant mass
spectrum recoiling against the charged , the charged
particle is found as a low mass enhancement. If a Breit-Wigner function of
constant width is used to parameterize the kappa, its pole locates at MeV/. Also in this channel,
the decay is observed for the first time.
Its branching ratio is .Comment: 14 pages, 4 figure
Simulated Milky Way analogues: implications for dark matter direct searches
We study the implications of galaxy formation on dark matter direct detection using high resolution hydrodynamic simulations of Milky Way-like galaxies simulated within the eagle and apostle projects. We identify MilkyWay analogues that satisfy observational constraints on the Milky Way rotation curve and total stellar mass. We then extract the dark matter density and velocity distribution in the Solar neighbourhood for this set of Milky Way analogues, and use them to analyse the results of current direct detection experiments. For most Milky Way analogues, the event rates in direct detection experiments obtained from the best _t Maxwellian distribution (with peak speed of 223 { 289 km=s) are similar to those obtained directly from the simulations. As a consequence, the allowed regions and exclusion limits set by direct detection experiments in the dark matter mass and spin-independent cross section plane shift by a few GeV compared to the Standard Halo Model, at low dark matter masses. For each dark matter mass, the halo-to-halo variation of the local dark matter density results in an overall shift of the allowed regions and exclusion limits for the cross section. However, the compatibility of the possible hints for a dark matter signal from
DAMA and CDMS-Si and null results from LUX and SuperCDMS is not improved
Evidence for kappa Meson Production in J/psi -> bar{K}^*(892)^0K^+pi^- Process
Based on 58 million BESII J/psi events, the bar{K}^*(892)^0K^+pi^- channel in
K^+K^-pi^+pi^- is studied. A clear low mass enhancement in the invariant mass
spectrum of K^+pi^- is observed. The low mass enhancement does not come from
background of other J/psi decay channels, nor from phase space. Two independent
partial wave analyses have been performed. Both analyses favor that the low
mass enhancement is the kappa, an isospinor scalar resonant state. The average
mass and width of the kappa in the two analyses are 878 +- 23^{+64}_{-55}
MeV/c^2 and 499 +- 52^{+55}_{-87} MeV/c^2, respectively, corresponding to a
pole at (841 +- 30^{+81}_{-73}) - i(309 +- 45^{+48}_{-72}) MeV/c^2.Comment: 17 pages, 5 figure
- …