We report the first observation of a$0\atop{0}$(980)-f0(980) mixing in the decays of J/$\psi$ → Φf0(980) → Φa$0\atop{0}$(980) → Φηπ0 and χc1 → a$0\atop{0}$(980)π0 → f0(980)π0 → π+ π- π0, using data ...samples of 1.31 × 109 J/$\psi$ events and 4.48 × 108 $\psi$(3686) events accumulated with the BESIII detector. The signals of f0(980) → a$0\atop{0}$(980) and a$0\atop{0}$(980) → f0(980) mixing are observed with a statistical significance of 7.4σ and 5.5σ, respectively. The corresponding branching fractions and mixing intensities are measured, and the constraint regions on the coupling constants, ga0K+K- and gf0K+K-, are estimated. The results improve the understanding of the nature of a$0\atop{0}$(980) and f0(980).
The process e+e− → ϕη' has been studied for the first time in detail using data sample collected with the BESIII detector at the BEPCII collider at center of mass energies from 2.05 to 3.08 GeV. A ...resonance with quantum numbers JPC = 1−− is observed with mass M = ( 2177.5 ± 4.8 ( stat ) ± 19.5 ( syst ) ) MeV / c2 and width Γ = ( 149.0 ± 15.6 ( stat ) ± 8.9 ( syst ) ) MeV with a statistical significance larger than 10 σ , including systematic uncertainties. If the observed structure is identified with the ϕ ( 2170 ) , then the ratio of partial width between the ϕ η ′ by BESIII and ϕ η by BABAR is (...) = 0.23 ± 0.10 ( stat ) ± 0.18 ( syst ) , which is smaller than the prediction of the s ¯ s g hybrid models by several orders of magnitude. (ProQuest: ... denotes formula omited.).
Using a sample of
1.31
×
10
9
J
/
ψ
events collected with the BESIII detector, we perform a study of
J
/
ψ
→
γ
K
K
¯
η
′
.
X
(2370) is observed in the
K
K
¯
η
′
invariant-mass distribution with a ...statistical significance of
8.3
σ
. Its resonance parameters are measured to be
M
=
2341.6
±
6.5
(stat.)
±
5.7
(syst.)
MeV
/
c
2
and
Γ
=
117
±
10
(stat.)
±
8
(syst.)
MeV
. The product branching fractions for
J
/
ψ
→
γ
X
(
2370
)
,
X
(
2370
)
→
K
+
K
-
η
′
and
J
/
ψ
→
γ
X
(
2370
)
,
X
(
2370
)
→
K
S
0
K
S
0
η
′
are determined to be
(
1.79
±
0.23
(stat.)
±
0.65
(syst.)
)
×
10
-
5
and
(
1.18
±
0.32
(stat.)
±
0.39
(syst.)
)
×
10
-
5
, respectively. No evident signal for
X
(2120) is observed in the
K
K
¯
η
′
invariant-mass distribution. The upper limits for the product branching fractions of
B
(
J
/
ψ
→
γ
X
(
2120
)
→
γ
K
+
K
-
η
′
)
and
B
(
J
/
ψ
→
γ
X
(
2120
)
→
γ
K
S
0
K
S
0
η
′
)
are determined to be
1.49
×
10
-
5
and
6.38
×
10
-
6
at the 90% confidence level, respectively.
We report the first measurement of absolute hadronic branching fractions of Λ_{c}^{+} baryon at the Λ_{c}^{+}Λover ¯_{c}^{-} production threshold, in the 30 years since the Λ_{c}^{+} discovery. In ...total, 12 Cabibbo-favored Λ_{c}^{+} hadronic decay modes are analyzed with a double-tag technique, based on a sample of 567 pb^{-1} of e^{+}e^{-} collisions at sqrts=4.599 GeV recorded with the BESIII detector. A global least-squares fitter is utilized to improve the measured precision. Among the measurements for twelve Λ_{c}^{+} decay modes, the branching fraction for Λ_{c}^{+}→pK^{-}π^{+} is determined to be (5.84±0.27±0.23)%, where the first uncertainty is statistical and the second is systematic. In addition, the measurements of the branching fractions of the other 11 Cabibbo-favored hadronic decay modes are significantly improved.
We study the decays Λc+→Ληπ+ and Σ(1385)+η based on Λc+Λ¯c− pairs produced in e+e− collisions at a center-of-mass energy of s=4.6 GeV, corresponding to an integrated luminosity of 567 pb−1. The data ...sample was accumulated with the BESIII detector at the BEPCII collider. The branching fractions are measured to be B(Λc+→Ληπ+)=(1.84±0.21(stat)±0.15(syst))% and B(Λc+→Σ(1385)+η)=(0.91±0.18(stat)±0.09(syst))%, constituting the most precise measurements to date.
The cross section of the process e+e− → ωχc0 is measured at center-of-mass energies from √s=4.178 to 4.278 GeV using a data sample of 7 fb−1 collected with the BESIII detector operating at the BEPCII ...storage ring. The dependence of the cross section on s shows a resonant structure with mass of (4218.5±1.6(stat)±4.0(syst)) MeV/c2 and width of (28.2±3.9(stat)±1.6(syst)) MeV, respectively. This observation confirms and improves upon the result of a previous study. The angular distribution of the e+e− → ωχc0 process is extracted for the first time.
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