Using a low background data sample of 9.7×10^{5} J/ψ→γη^{'}, η^{'}→γπ^{+}π^{-} events, which are 2 orders of magnitude larger than those from the previous experiments, recorded with the BESIII ...detector at BEPCII, the decay dynamics of η^{'}→γπ^{+}π^{-} are studied with both model-dependent and model-independent approaches. The contributions of ω and the ρ(770)-ω interference are observed for the first time in the decays η^{'}→γπ^{+}π^{-} in both approaches. Additionally, a contribution from the box anomaly or the ρ(1450) resonance is required in the model-dependent approach, while the process specific part of the decay amplitude is determined in the model-independent approach.
Based on electron-positron collision data collected with the BESIII detector operating at the Beijing Electron-Positron Collider II storage rings, the value of ...R≡σ(e^{+}e^{-}→hadrons)/σ(e^{+}e^{-}→μ^{+}μ^{-}) is measured at 14 center-of-mass energies from 2.2324 to 3.6710 GeV. The resulting uncertainties are less than 3.0% and are dominated by systematic uncertainties.
Use of energetic materials has long been considered for only military purposes. However, it is very recent that their practical applications in wide range of commercial fields such as mining, road ...building, under water blasting and rocket propulsion system have been considered. About 5mg of 2,4,6-trinitrotoluene (TNT) in serviceable (Svc) as well as unserviceable (Unsvc) form were used for their thermal decomposition and kinetic parameters investigation. Thermogravimetric differential thermal analysis (TG DTA), X-ray diffraction (XRD) and Scanning electron microscope (SEM) were used to characterize two types of TNT. Arrhenius kinetic parameters like activation energy (E) and enthalpy (AH) of both TNT samples were determined using TG curves with the help of Horowitz and Metzger method. Simultaneously, thermal decomposition range was evaluated from DTA curves. Distinct diffraction peaks showing crystalline nature were obtained from XRD analysis. SEM results indicated that Unsvc TNT contained a variety of defects like cracks and porosity. Similarly, it is observed that thermal as well as kinetic behavior of both TNT samples vary to a great extent. Likewise, a prominent change in the activation energies (E) of both samples is observed. This in-depth study provides a way forward in finding solutions for the safe reutilization of decanted TNT.
The cross section of the e+e−→Λc+Λ¯c− process is measured with unprecedented precision using data collected with the BESIII detector at /¯s=4574.5, 4580.0, 4590.0 and 4599.5 MeV. The nonzero cross ...section near the Λc+Λ¯c− production threshold is cleared. At center-of-mass energies /¯s=4574.5 and 4599.5 MeV, the higher statistics data enable us to measure the Λc polar angle distributions. From these, the Λc electric over magnetic form-factor ratios (|GE/GM|) are measured for the first time. They are found to be 1.14±0.14±0.07 and 1.23±0.05±0.03, respectively, where the first uncertainties are statistical and the second are systematic.
A
bstract
Using a data set corresponding to an integrated luminosity of 6.32 fb
−
1
recorded by the BESIII detector at center-of-mass energies between 4.178 and 4.226 GeV, an amplitude analysis of ...the decay
D
s
+
→
π
+
π
0
π
0
is performed, and the relative fractions and phases of different intermediate processes are determined. The absolute branching fraction of the decay
D
s
+
→
π
+
π
0
π
0
is measured to be (0
.
50 ± 0
.
04
stat
± 0
.
02
syst
)%. The absolute branching fraction of the intermediate process
D
s
+
→
f
0
(980)
π
+
, f
0
(980) →
π
0
π
0
is determined to be (0
.
28 ± 0
.
04
stat
± 0
.
04
syst
)%.
Using a sample of about 10(10) J/Psi events collected at a center-of-mass energy root s = 3.097 GeV with the BESIII detector, the electromagnetic Dalitz decays J/Psi -> e(+)e(-) pi(+)pi(-) eta', ...with eta' -> gamma pi(+)pi(-) and eta' -> pi(+)pi(-) eta, have been studied. The decay J/Psi -> e(+)e(-) X(1835) is observed with a significance of 15 sigma, and also an e(+)e(-) invariant-mass dependent transition form factor of J/Psi -> e(+)e(-) X(1835) is presented for the first time. The intermediate states X(2120) and X(2370) are also observed in the pi(+)pi(-) eta' invariant-mass spectrum with significances of 5.3 sigma and 7.3 sigma. The corresponding product branching fractions for J/Psi -> e(+)e(-) X, X -> pi(+) pi(-) eta' X = X(1835), X(2120), and X(2370) are reported.
Using 4.7 fb^{-1} of e^{+}e^{-} collision data at center-of-mass energies from 4.661 to 4.951 GeV collected by the BESIII detector at the BEPCII collider, we observe the X(3872) production process ...e^{+}e^{-}→ωX(3872) for the first time. The significance is 7.8σ, including both the statistical and systematic uncertainties. The e^{+}e^{-}→ωX(3872) Born cross section and the corresponding upper limit at 90% confidence level at each energy point are reported. The line shape of the cross section indicates that the ωX(3872) signals may be from the decays of some nontrivial structures.
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