3,165 research outputs found
Search for Light Weakly-Interacting-Massive-Particle Dark Matter by Annual Modulation Analysis with a Point-Contact Germanium Detector at the China Jinping Underground Laboratory
We present results on light weakly interacting massive particle (WIMP)
searches with annual modulation (AM) analysis on data from a 1-kg mass -type
point-contact germanium detector of the CDEX-1B experiment at the China Jinping
Underground Laboratory. Datasets with a total live time of 3.2 yr within a 4.2
yr span are analyzed with analysis threshold of 250 eVee. Limits on
WIMP-nucleus (-) spin-independent cross sections as function of WIMP
mass () at 90\% confidence level (C.L.) are derived using the dark
matter halo model. Within the context of the standard halo model, the 90\% C.L.
allowed regions implied by the DAMA/LIBRA and CoGeNT AM-based analysis are
excluded at 99.99\% and 98\% C.L., respectively. These results correspond to
the best sensitivity at 6 among WIMP AM
measurements to date.Comment: 5 pages, 4 figure
Limits on Light Weakly Interacting Massive Particles from the First 102.8 kg day Data of the CDEX-10 Experiment
We report the first results of a light weakly interacting massive particles
(WIMPs) search from the CDEX-10 experiment with a 10 kg germanium detector
array immersed in liquid nitrogen at the China Jinping Underground Laboratory
with a physics data size of 102.8 kg day. At an analysis threshold of 160 eVee,
improved limits of 8 and 3 cm at a
90\% confidence level on spin-independent and spin-dependent WIMP-nucleon cross
sections, respectively, at a WIMP mass () of 5 GeV/ are
achieved. The lower reach of is extended to 2 GeV/.Comment: 5 pages, 4 figure
Measurement of the chi_{c2} Polarization in psi(2S) to gamma chi_{c2}
The polarization of the chi_{c2} produced in psi(2S) decays into gamma
chi_{c2} is measured using a sample of 14*10^6 psi(2S) events collected by
BESII at the BEPC. A fit to the chi_{c2} production and decay angular
distributions in psi(2S) to gamma chi_{c2}, chi_{c2} to pi pi and KK yields
values x=A_1/A_0=2.08+/-0.44 and y=A_2/A_0=3.03 +/-0.66, with a correlation
rho=0.92 between them, where A_{0,1,2} are the chi_{c2} helicity amplitudes.
The measurement agrees with a pure E1 transition, and M2 and E3 contributions
do not differ significantly from zero.Comment: 6 pages, 4 figures, 1 tabl
Measurement of the branching fractions of psi(2S) -> 3(pi+pi-) and J/psi -> 2(pi+pi-)
Using data samples collected at sqrt(s) = 3.686GeV and 3.650GeV by the BESII
detector at the BEPC, the branching fraction of psi(2S) -> 3(pi+pi-) is
measured to be [4.83 +- 0.38(stat) +- 0.69(syst)] x 10^-4, and the relative
branching fraction of J/psi -> 2(pi+pi-) to that of J/psi -> mu+mu- is measured
to be [5.86 +- 0.19(stat) +- 0.39(syst)]% via psi(2S) -> (pi+pi-)J/psi, J/psi
-> 2(pi+pi-). The electromagnetic form factor of 3(pi+pi-) is determined to be
0.21 +- 0.02 and 0.20 +- 0.01 at sqrt(s) = 3.686GeV and 3.650GeV, respectively.Comment: 17pages, 7 figures, submitted to Phys. Rev.
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