A
bstract
Using a sample of (10
.
09
±
0
.
04)
×
10
9
J/ψ
decays collected with the BESIII detector, partial wave analyses of the decay
J
/
ψ
→
γ
K
S
0
K
S
0
π
0
are performed within the
K
S
0
K
S
0
...π
0
invariant mass region below 1.6 GeV/
c
2
. The covariant tensor amplitude method is used in both mass independent and mass dependent approaches. Both analysis approaches exhibit dominant pseudoscalar and axial vector components, and show good consistency for the other individual components. Furthermore, the mass dependent analysis reveals that the
K
S
0
K
S
0
π
0
invariant mass spectrum for the pseudoscalar component can be well described with two isoscalar resonant states using relativistic Breit-Wigner model, i.e., the
η
(1405) with a mass of
1391.7
±
0.7
−
0.3
+
11.3
MeV/
c
2
and a width of
60.8
±
1.2
−
12.0
+
5.5
MeV, and the
η
(1475) with a mass of
1507.6
±
1.6
−
32.2
+
15.5
MeV/
c
2
and a width of
115.8
±
2.4
−
10.9
+
14.8
MeV. The first and second uncertainties are statistical and systematic, respectively. Alternate models for the pseudoscalar component are also tested, but the description of the
K
S
0
K
S
0
π
0
invariant mass spectrum deteriorates significantly.
The as-grown CNTs and graphitized CNTs were used as adsorbents to remove 1,2-dichlorobenzene from water. The experiments demonstrate that it takes only 40 min for CNTs to attain equilibrium and the ...adsorption capacity of as-grown and graphitized CNTs is 30.8 and 28.7 mg/g, respectively, from a 20 mg/l solution. CNTs can be used as adsorbents in a wide pH range of 3–10. Thermodynamic calculations indicate that the adsorption reaction is spontaneous with a high affinity and the adsorption is an endothermic reaction.
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.
A
bstract
With data samples collected with the BESIII detector at seven energy points at
s
= 3
.
68
−
3
.
71 GeV, corresponding to an integrated luminosity of 333 pb
−
1
, we present a study of the Λ ...transverse polarization in the
e
+
e
−
→
Λ
Λ
¯
reaction. The significance of polarization by combining the seven energy points is found to be 2.6
σ
including the systematic uncertainty, which implies a non-zero phase between the transition amplitudes of the
Λ
Λ
¯
helicity states. The modulus ratio and the relative phase of EM-
psionic
form factors combined with all energy points are measured to be
R
Ψ
=
0.71
−
0.10
+
0.10
±
0.03 and ∆Φ
Ψ
=
23
−
8.0
+
8.8
±
1.6
°
, where the first uncertainties are statistical and the second systematic.
The HfC coatings can improve the ablation resistance of C/C composites effectively, and the HfC coatings with particle-stacked structure exhibit the favorable ablation resistance. Display omitted
► ...HfC coatings with different structures were deposited on C/C composites by CVD. ► HfC coatings with particle-stacked structure have the favorable ablation resistance. ► The ablation rate of HfC coating is controlled by various mechanisms.
HfC protective coatings with different structures were deposited on C/C composites by CVD. The microstructures, ablation properties and ablation behavior of the HfC coatings are investigated. Results show that the HfC coating with particle-stacked structure exhibits the favorable ablation resistance. The higher mass ablation rates of HfC coatings with columnar-arranged structure are contributed to the peeling of coatings. In different stages of ablation, the ablation rate of HfC coating is controlled by various mechanisms. The formation of porous HfO2, HfCxOy layer and molten HfO2, as well as the consumption of heat, are all beneficial to the protection for C/C composites.
The decay
D
→
K
-
π
+
is studied in a sample of quantum-correlated
D
D
¯
pairs, based on a data set corresponding to an integrated luminosity of 2.93 fb
-
1
collected at the
ψ
(
3770
)
resonance by ...the BESIII experiment. The asymmetry between
C
P
-odd and
C
P
-even eigenstate decays into
K
-
π
+
is determined to be
A
K
π
=
0.132
±
0.011
±
0.007
, where the first uncertainty is statistical and the second is systematic. This measurement is an update of an earlier study exploiting additional tagging modes, including several decay modes involving a
K
L
0
meson. The branching fractions of the
K
L
0
modes are determined as input to the analysis in a manner that is independent of any strong phase uncertainty. Using the predominantly
C
P
-even tag
D
→
π
+
π
-
π
0
and the ensemble of
C
P
-odd eigenstate tags, the observable
A
K
π
π
π
π
0
is measured to be
0.130
±
0.012
±
0.008
. The two asymmetries are sensitive to
r
D
K
π
cos
δ
D
K
π
, where
r
D
K
π
and
δ
D
K
π
are the ratio of amplitudes and phase difference, respectively, between the doubly Cabibbo-suppressed and Cabibbo-favoured decays. In addition, events containing
D
→
K
-
π
+
tagged by
D
→
K
S
,
L
0
π
+
π
-
are studied in bins of phase space of the three-body decays. This analysis has sensitivity to both
r
D
K
π
cos
δ
D
K
π
and
r
D
K
π
sin
δ
D
K
π
. A fit to
A
K
π
,
A
K
π
π
π
π
0
and the phase-space distribution of the
D
→
K
S
,
L
0
π
+
π
-
tags yields
δ
D
K
π
=
187.6
-
9.7
+
8.9
-
6.4
+
5.4
∘
, where external constraints are applied for
r
D
K
π
and other relevant parameters. This is the most precise measurement of
δ
D
K
π
in quantum-correlated
D
D
¯
decays.
A
bstract
Using (10087 ± 44) × 10
6
J
/
ψ
events collected with the BESIII detector at the BEPCII
e
+
e
−
storage ring at the center-of-mass energy of
s
= 3.097 GeV, we present a search for the rare ...semi-muonic charmonium decay
J
/
ψ
→
D
−
μ
+
ν
μ
+ c.c.. Since no significant signal is observed, we set an upper limit of the branching fraction to be
B
(
J
/
ψ
→
D
−
μ
+
ν
μ
+ c.c.) < 5.6 × 10
−
7
at 90% confidence level. This is the first search for the weak decay of charmonium with a muon in the final state.
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