Based on a data sample of 10 billion J / ψ events collected with the BESIII detector, improved measurements of the Dalitz decays η / η ′ → γ e + e − are performed, where the η and η ′ are produced ...through the radiative decays J / ψ → γ η / η ′ . The branching fractions of η → γ e + e − and η ′ → γ e + e − are measured to be ( 7.07 ± 0.05 ± 0.23 ) × 10 − 3 and ( 4.83 ± 0.07 ± 0.14 ) × 10 − 4 , respectively. Within the single-pole model, the parameter of electromagnetic transition form factor for η → γ e + e − is determined to be Λ η = ( 0.749 ± 0.027 ± 0.007 ) GeV / c 2 . Within the multipole model, we extract the electromagnetic transition form factors for η ′ → γ e + e − to be Λ η ′ = ( 0.802 ± 0.007 ± 0.008 ) GeV / c 2 and γ η ′ = ( 0.113 ± 0.010 ± 0.002 ) GeV / c 2 . The results are consistent with both theoretical predictions and previous measurements. The characteristic sizes of the interaction regions for the η and η ′ are calculated to be ( 0.645 ± 0.023 ± 0.007 ) fm and ( 0.596 ± 0.005 ± 0.006 ) fm , respectively. In addition, we search for the dark photon in η / η ′ → γ e + e − , and the upper limits of the branching fractions as a function of the dark photon are given at 90% confidence level. Published by the American Physical Society 2024
Using e + e − collision data collected with the BESIII detector operating at the BEPCII collider, the Born cross sections of e + e − → Λ c + Λ ¯ c ( 2595 ) − + c . c . and e + e − → Λ c + Λ ¯ c ( ...2625 ) − + c . c . are measured for the first time at center-of-mass energies of s = 4918.0 and 4950.9 MeV. Nonzero cross sections are observed very close to the production threshold. The measured Born cross sections of e + e − → Λ c + Λ ¯ c ( 2625 ) − + c . c . are about 2–3 times greater than those of e + e − → Λ c + Λ ¯ c ( 2595 ) − + c . c . , providing the similar behavior as semileptonic decays of Λ b 0 , but different behavior from that in the hadronic decays of Λ b 0 . The Born cross sections are 15.6 ± 3.1 ± 0.9 pb and 29.4 ± 3.7 ± 2.7 pb for e + e − → Λ c + Λ ¯ c ( 2595 ) − + c . c . , and are 43.4 ± 4.0 ± 4.1 pb and 76.8 ± 6.5 ± 4.2 pb for e + e − → Λ c + Λ ¯ c ( 2625 ) − + c . c . at s = 4918.0 and 4950.9 MeV, respectively. Based on the polar angle distributions of the Λ ¯ c ( 2625 ) − and Λ c ( 2625 ) + , the form-factor ratios | G E | 2 + 3 | G M | 2 / | G C | are determined for e + e − → Λ c + Λ ¯ c ( 2625 ) − + c . c . for the first time, which are 5.95 ± 4.07 ± 0.15 and 0.94 ± 0.32 ± 0.02 at s = 4918.0 and 4950.9 MeV, respectively. All of these first uncertainties are statistical and second systematic. Published by the American Physical Society 2024
The cross sections of the e + e − → ϕη′ process at center-of-mass energies from 3.508 to 4.951 GeV are measured with high precision using 26.1 fb −1 data collected with the BESIII detector operating ...at the BEPCII storage ring. The cross sections are of the order of a few picobarn and decrease as the center-of-mass energy increases as s −n/2 with n = 4.35±0.14. This result is in agreement with the Nambu-Jona-Lasinio model prediction of n = 3.5±0.9. In addition, the charmless decay ψ(3770) → ϕη′ is searched for by fitting the measured cross sections, yet no significant signal is observed. The upper limit of B(ψ(3770) → ϕη′) at the 90% confidence level is determined to be 2.3×10 −5 .
Enzymes in Plant Metabolism of PCBs and PAHs Chroma, L.; Mackova, M.; Kucerova, P. ...
Acta biotechnologica,
01/2002, Letnik:
22, Številka:
1-2
Journal Article, Conference Proceeding
Recenzirano
Odprti dostop
Recently it has been shown that plants are able to transform polychlorinated biphenyls (PCBs) as well as polycyclic aromatic hydrocarbons (PAHs), but the knowledge of enzymes involved in these ...metabolic processes is limited. Plant peroxidases generally play an important role in plant metabolism. On the other hand, cytochrome P450 is involved in the detoxification of various xenobiotics in the cells of higher organisms. In this work, several in vitro cultures of different plant species were screened for their ability to transform PCBs or PAHs, and compared regarding their total extra‐ and intracellular peroxidase activity. Cultures with good transformation ability exhibited in the presence of xenobiotics the same or higher levels of peroxidases as the controls incubated without contaminants. Cultures with markedly lower peroxidase activity exhibited also lower PCB/PAH conversion in the presence of PCBs/PAHs. It was attempted to identify lignin peroxidase and Mn‐peroxidase in plants, originally described in white rot fungi to be responsible for the degradation of PCBs and other environmental pollutants. In addition to different types of peroxidases, RBBR oxidase was also detected in plants. The decolourisation of RBBR during the growth on agar plates was used as a rough screening method for plant cells able to metabolise PCBs/PAHs efficiently. The exact type of transformation reaction (peroxidative or oxidative) was studied using various inhibitors and inducers of peroxidases and cytochrome P450. It was shown that both enzymatic systems are partially involved in the detoxification mechanism of chosen xenobiotics in plants.
We present a measurement of the integrated luminosity of \(e^+e^-\) collision data collected with the BESIII detector at the BEPCII collider at a center-of-mass energy of \(E_{\rm cm} = 3.773\)~GeV. ...The integrated luminosities of the data sets taken from December 2021 to June 2022, from November 2022 to June 2023, and from October 2023 to February 2024 are determined to be \(4.995 \pm 0.019\)~fb\(^{-1}\), \(8.157 \pm 0.031\)~fb\(^{-1}\), and \(4.191 \pm 0.016\)~fb\(^{-1}\), respectively, by analyzing large angle Bhabha scattering events. The uncertainties are dominated by systematic effects and the statistical uncertainties are negligible. Our results provide essential input for future analyses and precision measurements.
We search for the di-photon decay of a light pseudoscalar axion-like particle, \(a\), in radiative \(J/\psi\) decays, using 10 billion \(J/\psi\) events collected with the BESIII detector. We find no ...evidence of a signal and set upper limits at the \(95\%\) confidence level on the product branching fraction \(\mathcal{B}(J/\psi \to \gamma a) \times \mathcal{B}(a \to \gamma \gamma)\) and the axion-like particle photon coupling constant \(g_{a \gamma \gamma}\) in the ranges of \((3.7-48.5) \times 10^{-8}\) and \((2.2 -101.8)\times 10^{-4}\) GeV\(^{-1}\), respectively, for \(0.18 \le m_a \le 2.85\) GeV/\(c^2\). These are the most stringent limits to date in this mass region.
A high precision measurement of the branching fraction of the decay \(J/\psi \to p \bar{p} \eta\) is performed using \((10 087 \pm 44) \times 10^6\) \(J/\psi\) events recorded by the {BESIII} ...detector at the {BEPCII} storage ring. The branching fractions of the two decays \(J/\psi \to p \bar{p} \eta(\eta \to \gamma\gamma)\) and \(J/\psi \to p \bar{p} \eta(\eta \to \pi^+ \pi^- \pi^0)\) are measured individually to be \(\mathcal{B}(J/\psi \to p \bar{p} \eta(\eta \to \gamma\gamma)) = (1.480 \pm 0.001 \pm 0.024)\times\,10^{-3}\) and \(\mathcal{B}(J/\psi \to p \bar{p} \eta(\eta \to \pi^+ \pi^- \pi^0)) = (1.557 \pm 0.003 \pm 0.038)\times\,10^{-3}\), where the first uncertainties are statistical and the second systematic. Both results are compatible within their uncorrelated systematic uncertainties. The combined result is \(\mathcal{B}(J/\psi \to p \bar{p} \eta)=(1.495 \pm 0.001 \pm 0.023)\times\,10^{-3}\) where the first uncertainty is the combined statistical uncertainty and the second one the combined systematic uncertainty of both analyses, incorporating correlations between them. In addition, the \(p \bar{p}\) threshold region is investigated for a potential threshold enhancement, and no evidence for one is observed.
Analyzing \(e^+e^-\) collision data corresponding to an integrated luminosity of \(7.33~\mathrm{fb}^{-1}\) collected at center-of-mass energies between 4.128 and 4.226~GeV with the BESIII detector, ...we measure the branching fraction of the semileptonic decay \(D^+_{s}\to K^0 e^+\nu_e\) to be \((2.98\pm0.23\pm0.12)\times10^{-3}\). The \(D_s^+\to K^0\) hadronic form factor is determined from the differential decay rate of \(D^+_s\to K^0 e^+\nu_e\) to be \(f^{K^0}_+(0)=0.636\pm0.049\pm0.013\). For both measurements, the first uncertainty is statistical and the second systematic. The branching fraction and form factor measurements are factors of 1.6 and 1.7 more precise than the previous world averages, respectively.
Using \(e^+e^-\) collision data collected with the BESIII detector at the BEPCII collider at center-of-mass energies between 3.510 and 4.914GeV, corresponding to an integrated luminosity of 25 ...fb\(^{-1}\), we measure the Born cross sections for the process \(e^+e^-\to K^-\bar{\Xi}^+\Lambda/\Sigma^{0}\) at thirty-five energy points with a partial-reconstruction strategy. By fitting the dressed cross sections of \(e^+e^-\to K^-\bar{\Xi}^+\Lambda/\Sigma^{0}\), evidence for \(\psi(4160) \to K^{-}\bar\Xi^{+}\Lambda\) is found for the first time with a significance of 4.4\(\sigma\), including systematic uncertainties. No evidence for other possible resonances is found. In addition, the products of electronic partial width and branching fraction for all assumed resonances decaying into \(K^{-}\bar\Xi^{+}\Lambda/\Sigma^{0}\) are determined.
