376 research outputs found
Search for the decay
We search for radiative decays into a weakly interacting neutral
particle, namely an invisible particle, using the produced through the
process in a data sample of
decays collected by the BESIII detector
at BEPCII. No significant signal is observed. Using a modified frequentist
method, upper limits on the branching fractions are set under different
assumptions of invisible particle masses up to 1.2 . The upper limit corresponding to an invisible particle with zero mass
is 7.0 at the 90\% confidence level
Observation of eight-photon entanglement
Using ultra-bright sources of pure-state entangled photons from parametric
down conversion, an eight-photon interferometer and post-selection detection,
we demonstrate the ability to experimentally manipulate eight individual
photons and report the creation of an eight-photon Schr\"odinger cat state with
an observed fidelity of .Comment: 6 pages, 4 figure
Studies on Preparation of Photosensitizer Loaded Magnetic Silica Nanoparticles and Their Anti-Tumor Effects for Targeting Photodynamic Therapy
As a fast developing alternative of traditional therapeutics, photodynamic therapy (PDT) is an effective, noninvasive, nontoxic therapeutics for cancer, senile macular degeneration, and so on. But the efficacy of PDT was compromised by insufficient selectivity and low solubility. In this study, novel multifunctional silica-based magnetic nanoparticles (SMNPs) were strategically designed and prepared as targeting drug delivery system to achieve higher specificity and better solubility. 2,7,12,18-Tetramethyl-3,8-di-(1-propoxyethyl)-13,17-bis-(3-hydroxypropyl) porphyrin, shorted as PHPP, was used as photosensitizer, which was first synthesized by our lab with good PDT effects. Magnetite nanoparticles (Fe3O4) and PHPP were incorporated into silica nanoparticles by microemulsion and sol–gel methods. The prepared nanoparticles were characterized by transmission electron microscopy, X-ray diffraction, Fourier transform infrared spectroscopy and fluorescence spectroscopy. The nanoparticles were approximately spherical with 20–30 nm diameter. Intense fluorescence of PHPP was monitored in the cytoplasm of SW480 cells. The nanoparticles possessed good biocompatibility and could generate singlet oxygen to cause remarkable photodynamic anti-tumor effects. These suggested that PHPP-SMNPs had great potential as effective drug delivery system in targeting photodynamic therapy, diagnostic magnetic resonance imaging and magnetic hyperthermia therapy
Measurements of the absolute branching fractions of decays
Based on 2.93~fb collision data taken at center-of-mass
energy of 3.773 GeV by the BESIII detector, we report the measurements of the
absolute branching fractions of , , , , , ,
, , and . The decays , , , , and are observed for the
first time. The branching fractions of the decays , , ,
and are measured with improved precision compared
to the world-average values.Comment: 11 pages, 5 figure
Measurement of the branching fraction of and search for a CP-violating asymmetry in η′→π+π−e+e− at BESIII
The rare decay η′→π+π-e+e- is studied using a sample of 1.3×109 J/ψ events collected with the BESIII detector at BEPCII in 2009 and 2012. The branching fraction is measured with improved precision to be (2.42±0.05stat±0.08syst)×10-3. Due to the inclusion of new data, this result supersedes the last BESIII result on this branching fraction. In addition, the CP-violating asymmetry in the angle between the decay planes of the π+π - pair and the e+e - pair is investigated. A measurable value would indicate physics beyond the standard model; the result is ACP=(2.9±3.7stat±1.1syst)%, which is consistent with the standard model expectation of no CP-violation. The precision is comparable to the asymmetry measurement in the KL0→π+π-e+e- decay where the observed (14±2)% effect is driven by a standard model mechanism
Observation of a structure in at from 2.05 to 3.08 GeV
The process has been studied for the
first time in detail using data sample collected with the BESIII detector at
the BEPCII collider at center of mass energies from 2.05 to 3.08 GeV. A
resonance with quantum numbers is observed with mass =
(2177.5 4.8 (stat) 19.5 (syst)) MeV/ and
width = (149.0 15.6 (stat) 8.9 (syst)) MeV with a
statistical significance larger than 10. The observed structure could
be identified with the , then the ratio of partial width between
the by BESIII and by BABAR is
( = 0.23 0.10 (stat) 0.18 (syst),
which is smaller than the prediction of the hybrid models by
several orders of magnitude
Search for the semileptonic decay
Using of annihilation data collected at a
center-of-mass energy GeV with the BESIII detector operating
at the BEPCII collider, we search for the semileptonic decays into a
axial-vector meson for the first time. No significant signal
is observed for either charge combination. The upper limits on the product
branching fractions are and at the 90\% confidence level.Comment: 9 pages, 3 figure
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