Observation of Amoroso, A.; Bortone, A.; Briere, R. A. ...
Chinese physics C,
04/2023, Letnik:
47, Številka:
4
Journal Article
Recenzirano
Odprti dostop
Abstract
Using data taken at 29 center-of-mass energies between 4.16 and 4.70 GeV with the BESIII detector at the Beijing Electron Positron Collider corresponding to a total integrated luminosity of ...approximately 18.8
, the process
is observed for the first time with a statistical significance of
. The average Born cross sections in the energy ranges of (4.160, 4.380) GeV, (4.400, 4.600) GeV and (4.610, 4.700) GeV are measured to be
fb,
fb and
fb, respectively, where the first uncertainties are statistical and the second are systematic. The line shapes of the
and
invariant mass spectra are consistent with phase space distributions, indicating that no hexaquark or di-baryon state is observed.
A long-term mining activity of Jinding Pb-Zn mine area in Yunnan has caused the serious cadmium pollution to the river sediments of the ambient area. The Cd contents of Beidagou river sediments (mean ...value <10 mg x kg(-1)) are lower than those of Nandagou river sediments (mean value = 266 mg x kg(-1)). The Cd contents of river sediments in different section of Bijiang river occur distinct difference. The Cd contents are rather lower in upstream sediments of Bijiang river, and increase substantially along downstream contaminated section of Bijiang river. The Cd pollution coefficient is higher (R = 21.9-45.2) than Zn (R = 4.9-9.7) and Pb (R = 2.7-4.6). The degree of pollution is estimated by the geoaccumulation index, which indicates the following rank of pollution elements: Cd > Zn > Pb. The river sediments are extremely contaminated in Nandagou river and downstream section of Bijiang river from Nandagou, strongly contaminated in most part of Beidagou river, moderately to strongly contaminated in few river sec
Experimental research on the evolution characteristics of diesel particles under the cooling conditions has been carried out. The results showed that the cooling of the exhaust had important effect ...on the mass concentration of the diesel particles in the exhaust. The main cause that resulted in the change of the particle mass concentration was the condensation of gaseous hydrocarbon on the particle surface or existing in the form of liquid drop. The cooling of the exhaust promoted the increasing of the particle dimension and the decreasing of the particle numbers, especially for the smaller particles below 0.1 microm. The cooling temperature of the exhaust had important effect on the evolution of diesel particles. After exhaust cooling, the volume concentration of diesel particles between 0.1 microm and 1.0 microm exhibited a tendency of decreasing. Moreover, exhaust velocity also had effect on the evolution of the diesel particles. The number concentration and volume concentration of the diesel particles bet
Abstract
The cross sections of
at center-of-mass energies from 4.127 to 4.600 GeV are measured based on 15.6 fb
data collected with the BESIII detector operating at the BEPCII storage ring. Two ...resonant structures are observed in the line shape of the cross sections. The mass and width of the first structure are measured to be (
) MeV and (
) MeV, respectively. They are consistent with those of the established
. The second structure is observed for the first time with a statistical significance greater than 8
σ
, denoted as
. Its mass and width are determined to be (
) MeV and (
) MeV, respectively. The first presented uncertainties are statistical and the second ones are systematic. The product of the electronic partial width with the decay branching fraction
is reported.
Using a data sample of e+e- collision data corresponding to an integrated luminosity of 2.93 fb-1 collected with the BESIII detector at a center-of-mass energy of √s = 3.773 GeV, we search for the ...singly Cabibbo-suppressed decays D0 → π0π0π0, π0π0η, π0ηη and ηηη using the double tag method. The absolute branching fractions are measured to be B(D0 → π0π0π0) = (2.0 ± 0.4 ± 0.3) × 10-4, B(D0 → π0π0η) = (3.8 ± 1.1 ± 0.7) × 10-4 and B(D0 → π0ηη) = (7.3 ± 1.6 ± 1.5) × 10-4 with the statistical significances of 4.8σ, 3.8σ and 5.5σ, respectively, where the first uncertainties are statistical and the second ones systematic. No significant signal of D0 → ηηη is found, and the upper limit on its decay branching fraction is set to be B(D0 → ηηη) < 1.3 × 10-4 at the 90% confidence level.
Equilibrium sorption isotherms and sorption kinetics of 2,4-dichlorophenol (2,4-DCP) on live and chemically inactivated anaerobic granules were investigated using batch serum bottle tests. A general ...metabolic inhibitor, sodium azide, was used to inactivate the biological activity of the anaerobic biomass. Experimental results showed that the difference in the biosorption of live and chemically inactivated anaerobic granules were not significant, suggesting that anaerobic biosorption is mainly a physical-chemical process and that metabolically mediated diffusion in the process is negligible.
Using a data set of 2.93 fb-1 taken at a center-of-mass energy √s=3.773 GeV with the BESIII detector at the BEPCII collider, we perform a search for an extra U(1) gauge boson, also denoted as a dark ...photon. We examine the initial state radiation reactions e+e- → e+e-γISR and e+e- → μ+μ-γISR for this search, where the dark photon would appear as an enhancement in the invariant mass distribution of the leptonic pairs. We observe no obvious enhancement in the mass range between 1.5 and 3.4 GeV/c2 and set a 90% confidence level upper limit on the mixing strength of the dark photon and the Standard Model photon. We obtain a competitive limit in the tested mass range.
PDF
