29 research outputs found
Measurements of the observed cross sections for exclusive light hadron production in e^+e^- annihilation at \sqrt{s}= 3.773 and 3.650 GeV
By analyzing the data sets of 17.3 pb taken at GeV
and 6.5 pb taken at GeV with the BESII detector at the
BEPC collider, we have measured the observed cross sections for 12 exclusive
light hadron final states produced in annihilation at the two energy
points. We have also set the upper limits on the observed cross sections and
the branching fractions for decay to these final states at 90%
C.L.Comment: 8 pages, 5 figur
Search for the Rare Decays J/Psi --> Ds- e+ nu_e, J/Psi --> D- e+ nu_e, and J/Psi --> D0bar e+ e-
We report on a search for the decays J/Psi --> Ds- e+ nu_e + c.c., J/Psi -->
D- e+ nu_e + c.c., and J/Psi --> D0bar e+ e- + c.c. in a sample of 5.8 * 10^7
J/Psi events collected with the BESII detector at the BEPC. No excess of signal
above background is observed, and 90% confidence level upper limits on the
branching fractions are set: B(J/Psi --> Ds- e+ nu_e + c.c.)<4.8*10^-5, B(J/Psi
--> D- e+ nu_e + c.c.) D0bar e+ e- + c.c.)<1.1*10^-5Comment: 10 pages, 4 figure
Measurements of psi(2S) decays to octet baryon-antibaryon pairs
With a sample of 14 million psi(2S) events collected by the BESII detector at
the Beijing Electron Positron Collider (BEPC), the decay channels psi(2S)->p
p-bar, Lambda Lambda-bar, Sigma0 Sigma0-bar, Xi Xi-bar are measured, and their
branching ratios are determined to be (3.36+-0.09+-0.24)*10E-4,
(3.39+-0.20+-0.32)*10E-4, (2.35+-0.36+-0.32)*10E-4, (3.03+-0.40+-0.32)*10E-4,
respectively. In the decay psi(2S)->p p-bar, the angular distribution parameter
alpha is determined to be 0.82+-0.17+-0.04.Comment: 8 pages, 8 figure
Anomalous Line-Shape of Cross Sections for in the Center-of-Mass Energy Region between 3.650 and 3.872 GeV
We observe an obvious anomalous line-shape of the total cross sections in the energy region between 3.700 and 3.872 GeV from the data samples taken with the BES-II detector at the BEPC Collider. Re-analysis of the data shows that it is inconsistent with the explanation for only one simple resonance with a statistical significance of . The anomalous line-shape may be explained by two possible enhancements of the inclusive hadron production near the center-of-mass energies of 3.764 GeV and 3.779 GeV, indicating that either there is likely a new structure in addition to the resonance around 3.773 GeV, or there are some physics effects reflecting the production dynamics
Direct measurement of the absolute branching fraction for and determination of
The absolute branching fraction for the decay is determined using singly tagged
sample from the data collected around 3.773 GeV with the BESII detector at the
BEPC collider. In the system recoiling against the singly tagged mesons,
events for are observed. These
yield the absolute branching fraction to be . The ratio of the two partial widths for the decays and is determined to be
.Comment: 6 pages, 5 figure
First observation of J/\psi and \psi(2S) decaying to n K^0_S\bar\Lambda +c.c
The decays of \jpsi and \psip to are
observed and measured for the first time, and the perturbative QCD ``12%'' rule
is tested, based on \jpsi and \psip
events collected with BESII detector at the Beijing Electron-Positron Collider.
No obvious enhancement near threshold in \jpsi \to
{n}{K^0_S}\bar{\Lambda}+c.c. is observed, and the upper limit on the branching
ratio of \jpsi \to {K^0_S} X, X \to n \bar \Lambda is determined.Comment: 10 pages, 10 figure
Measurement of \chi_cJ--> K+K-K+K-
Using 14M psi(2S) events taken with the BES-II detector, chi_cJ-->K+K-K+K-
decays are studied. For the four-kaon final state, the branching fractions are
B(chi_c0,1,2 -->K+K-K+K-)=(3.48\pm 0.23\pm 0.47)\times 10^{-3}, (0.70\pm
0.13\pm 0.10)\times 10^{-3}, and (2.17\pm 0.20\pm 0.31)\times 10^{-3}. For the
\phi K+K- final state, the branching fractions, which are measured for the
first time, are B(chi_c0,1,2-->\phi K+K-)=(1.03\pm 0.22\pm 0.15)\times 10^{-3},
(0.46\pm 0.16\pm 0.06)\times 10^{-3}, and (1.67\pm 0.26\pm 0.24)\times 10^{-4}.
For the \phi\phi final state, B(chi_{c0,2}-->\phi\phi)=(0.94\pm 0.21\pm
0.13)\times 10^{-3} and (1.70\pm 0.30\pm 0.25)\times 10^{-3}.Comment: 7 pages, 7 figure
Partial wave analyses of J/psi to gamma pi^+ pi^- and gamma pi^0 pi^0
Results are presented on J/psi radiative decays to pi^+pi^- and pi^0pi^0
based on a sample of 58M J/psi events taken with the BESII detector. Partial
wave analyses are carried out using the relativistic covariant tensor amplitude
method in the 1.0 to 2.3 GeV/c^2 pipi mass range. There are conspicuous peaks
due to the f_2(1270) and two 0^++ states in the 1.45 and 1.75 GeV/c^2 mass
regions. The first 0^++ state has a mass of 1466\pm 6\pm 20 MeV/c^2, a width of
108^{+14}_{-11}\pm 25 MeV/c^2, and a branching fraction B(J/psi \to \gamma
f_0(1500) \to\gamma \pi^+\pi^-) = (0.67\pm0.02\pm0.30) \times 10^{-4}. Spin 0
is strongly preferred over spin 2. The second 0^++ state peaks at
1765^{+4}_{-3}\pm 13 MeV/c^2 with a width of 145\pm8\pm69 MeV/c^2. If this 0^++
is interpreted as coming from f_0(1710), the ratio of its branching fractions
to pipi and K\bar K is 0.41^{+0.11}_{-0.17}.Comment: 9 pages, 6 figure
Study of J\psi decaying into \omega p \bar p
The decay is studied using a
event sample accumulated with the BES II detector at the Beijing
electron-positron collider. The decay branching fraction is measured to be
. No
significant enhancement near the mass threshold is observed, and an
upper limit of is determined at the 95% confidence level, where X(1860)
designates the near-threshold enhancement seen in the mass spectrum
in decays.Comment: 5 pages, 4 figure
The global burden of cancer attributable to risk factors, 2010–19: a systematic analysis for the Global Burden of Disease Study 2019
BACKGROUND: Understanding the magnitude of cancer burden attributable to potentially modifiable risk factors is crucial for development of effective prevention and mitigation strategies. We analysed results from the Global Burden of Diseases, Injuries, and Risk Factors Study (GBD) 2019 to inform cancer control planning efforts globally. METHODS: The GBD 2019 comparative risk assessment framework was used to estimate cancer burden attributable to behavioural, environmental and occupational, and metabolic risk factors. A total of 82 risk–outcome pairs were included on the basis of the World Cancer Research Fund criteria. Estimated cancer deaths and disability-adjusted life-years (DALYs) in 2019 and change in these measures between 2010 and 2019 are presented. FINDINGS: Globally, in 2019, the risk factors included in this analysis accounted for 4·45 million (95% uncertainty interval 4·01–4·94) deaths and 105 million (95·0–116) DALYs for both sexes combined, representing 44·4% (41·3–48·4) of all cancer deaths and 42·0% (39·1–45·6) of all DALYs. There were 2·88 million (2·60–3·18) risk-attributable cancer deaths in males (50·6% [47·8–54·1] of all male cancer deaths) and 1·58 million (1·36–1·84) risk-attributable cancer deaths in females (36·3% [32·5–41·3] of all female cancer deaths). The leading risk factors at the most detailed level globally for risk-attributable cancer deaths and DALYs in 2019 for both sexes combined were smoking, followed by alcohol use and high BMI. Risk-attributable cancer burden varied by world region and Socio-demographic Index (SDI), with smoking, unsafe sex, and alcohol use being the three leading risk factors for risk-attributable cancer DALYs in low SDI locations in 2019, whereas DALYs in high SDI locations mirrored the top three global risk factor rankings. From 2010 to 2019, global risk-attributable cancer deaths increased by 20·4% (12·6–28·4) and DALYs by 16·8% (8·8–25·0), with the greatest percentage increase in metabolic risks (34·7% [27·9–42·8] and 33·3% [25·8–42·0]). INTERPRETATION: The leading risk factors contributing to global cancer burden in 2019 were behavioural, whereas metabolic risk factors saw the largest increases between 2010 and 2019. Reducing exposure to these modifiable risk factors would decrease cancer mortality and DALY rates worldwide, and policies should be tailored appropriately to local cancer risk factor burden