A bstract Using e + e − collision data collected with the BESIII detector at the BEPCII collider at center-of-mass energies between 3.510 and 4.914 GeV, corresponding to an integrated luminosity of ...25 fb − 1 , we measure the Born cross sections for the process $$ {e}^{+}{e}^{-}\to {K}^{-}{\overline{\Xi}}^{+}\Lambda /{\Sigma}^0 $$ e + e − → K − Ξ ¯ + Λ / Σ 0 at thirty-five energy points with a partial-reconstruction strategy. By fitting the dressed cross sections of $$ {e}^{+}{e}^{-}\to {K}^{-}{\overline{\Xi}}^{+}\Lambda /{\Sigma}^0 $$ e + e − → K − Ξ ¯ + Λ / Σ 0 , evidence for $$ \psi (4160)\to {K}^{-}{\overline{\Xi}}^{+}\Lambda $$ ψ 4160 → K − Ξ ¯ + Λ is found for the first time with a significance of 4.4 σ , 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 $$ {K}^{-}{\overline{\Xi}}^{+}\Lambda /{\Sigma}^0 $$ K − Ξ ¯ + Λ / Σ 0 are determined.
A bstract We measured the Born cross sections for the process e + e − → ωη ′ at 22 center-of-mass energies from 2.000 to 3.080 GeV with the BESIII detector at the BEPCII collider. We observed a ...resonant structure with a statistical significance of 9.6 σ . A Breit-Wigner fit determines its mass to be M R = (2153 ± 30 ± 31) MeV /c 2 and its width to be Γ R = (167 ± 77 ± 7) MeV, where the first uncertainties are statistical and the second are systematic.
A bstract Using e + e − collision data collected at the BESIII detector at center-of-mass energies between 4.128 and 4.226 GeV, corresponding to an integrated luminosity of 7 . 33 fb − 1 , we ...determine the absolute branching fractions of fifteen hadronic $$ {D}_s^{+} $$ D s + decays with a double-tag technique. In particular, we make precise measurements of the branching fractions $$ \mathcal{B}\left({D}_s^{+}\to {K}^{+}{K}^{-}{\pi}^{+}\right)=\left(5.49\pm 0.04\pm 0.07\right)\% $$ B D s + → K + K − π + = 5.49 ± 0.04 ± 0.07 % , $$ \mathcal{B}\left({D}_s^{+}\to {K}_S^0{K}^{+}\right)=\left(1.50\pm 0.01\pm 0.01\right)\% $$ B D s + → K S 0 K + = 1.50 ± 0.01 ± 0.01 % and $$ \mathcal{B}\left({D}_s^{+}\to {K}^{+}{K}^{-}{\pi}^{+}{\pi}^0\right)=\left(5.50\pm 0.05\pm 0.11\right)\% $$ B D s + → K + K − π + π 0 = 5.50 ± 0.05 ± 0.11 % , where the first uncertainties are statistical and the second ones are systematic. The CP asymmetries in these decays are also measured and all are found to be compatible with zero.
A bstract Using 24.1 fb − 1 of e + e − collision data collected with the BESIII detector at the BEPCII collider, the Born cross sections and effective form factors of the $$ {e}^{+}{e}^{-}\to ...{\Sigma}^{+}{\overline{\Sigma}}^{-} $$ e + e − → Σ + Σ ¯ − reaction are measured. The measurements are performed at center-of-mass energies ranging from 3.510 to 4.951 GeV. No significant evidence for the decay of the charmonium(-like) states, ψ (3770), ψ (4040), ψ (4160), Y (4230), Y (4360), ψ (4415), and Y (4660), into a $$ {\Sigma}^{+}{\overline{\Sigma}}^{-} $$ Σ + Σ ¯ − final state is observed. Consequently, upper limits for the products of the branching fractions and the electronic partial widths at the 90% confidence level are reported for these decays.
A bstract Using (27 . 12 ± 0 . 14) × 10 8 ψ (3686) events collected with the BESIII detector at BEPCII, the decay of ψ (3686) → $$ {\varOmega}^{-}{K}^{+}{\overline{\Xi}}^0 $$ Ω − K + Ξ ¯ 0 + c . c . ...is observed for the first time. The branching fraction of this decay is measured to be $$ {\mathcal{B}}_{\psi (3686)\to {\varOmega}^{-}{K}^{+}{\overline{\Xi}}^0+\textrm{c}.\textrm{c}.} $$ B ψ 3686 → Ω − K + Ξ ¯ 0 + c . c . = (2 . 78 ± 0 . 40 ± 0 . 18) × 10 − 6 , where the first uncertainty is statistical and the second is systematic. Possible baryon excited states are searched for in this decay, but no evident intermediate state is observed with the current sample size.
A
bstract
Based on
e
+
e
−
collision data collected at center-of-mass energies from 2.000 to 3.080 GeV by the BESIII detector at the BEPCII collider, a partial wave analysis is performed for the ...process
e
+
e
−
→
$$ {K}_S^0{K}_L^0 $$
K
S
0
K
L
0
π
0
. The results allow the Born cross sections of the process
e
+
e
−
→
$$ {K}_S^0{K}_L^0 $$
K
S
0
K
L
0
π
0
, as well as its subprocesses
e
+
e
−
→
K
∗
(892)
0
$$ \overline{K} $$
K
¯
0
and
$$ {K}_2^{\ast } $$
K
2
∗
(1430)
0
$$ \overline{K} $$
K
¯
0
to be measured. The Born cross sections for
e
+
e
−
→
$$ {K}_S^0{K}_L^0 $$
K
S
0
K
L
0
π
0
are consistent with previous measurements by BaBar, but with substantially improved precision. The Born cross section lineshape of the process
e
+
e
−
K
∗
(892)
0
$$ \overline{K} $$
K
¯
0
is consistent with a vector meson state around 2.2 GeV with a significance of 3.2
σ
. A Breit-Wigner fit determines its mass as
M
Y
= (2164
.
7
±
9
.
1
±
3
.
1) MeV
/c
2
and its width as Γ
Y
= (32
.
4
±
21
.
0
±
1
.
8) MeV.
The Beijing Electron Spectrometer III (BESIII) is a multipurpose detector operating on the Beijing Electron Positron Collider II (BEPCII). After more than ten years operation, the efficiency of the ...inner layers of the Main Drift Chamber (MDC) decreased significantly. To solve this issue, the BESIII collaboration is planning to replace the inner part of the MDC with three layers of Cylindrical triple Gas Electron Multipliers (CGEM).
The transverse plane spatial resolution of CGEM is required to be 120μm or better. To meet this goal, a careful calibration of the detector is necessary to fully exploit the potential of the CGEM detector. In all the calibrations, the detector alignment plays an important role to improve the detector precision. The track-based alignment for the CGEM detector with the Millepede algorithm is implemented to reduce the uncertainties of the hit position measurement. Using the cosmic-ray data taken in 2020 with the two layers setup, the displacement and rotation of the outer layer with respect to the inner layer is determined by a simultaneous fit applied to more than 160000 tracks. A good alignment precision has been achieved that guarantees the design request could be satisfied in the future. A further alignment is going to be performed using the combined information of tracks from cosmic-ray and collisions after the CGEM is installed into the BESIII detector.
A
bstract
The
$$ {D}_s^{+}\to {K}^{+}{K}^{-}{\mu}^{+}{\nu}_{\mu } $$
D
s
+
→
K
+
K
−
μ
+
ν
μ
decay is studied based on 7.33 fb
−
1
of
e
+
e
−
collision data collected with the BESIII detector at ...center-of-mass energies in the range from 4.128 to 4.226 GeV. The absolute branching fraction is measured as
$$ \mathcal{B}\left({D}_s^{+}\to \phi {\mu}^{+}{\nu}_{\mu}\right)=\left(2.25\pm 0.09\pm 0.07\right)\times {10}^{-2} $$
B
D
s
+
→
ϕ
μ
+
ν
μ
=
2.25
±
0.09
±
0.07
×
10
−
2
, the most precise measurement to date. Combining with the world average of
$$ \mathcal{B}\left({D}_s^{+}\to \phi {e}^{+}{\nu}_e\right) $$
B
D
s
+
→
ϕ
e
+
ν
e
, the ratio of the branching fractions obtained is
$$ \frac{\mathcal{B}\left({D}_s^{+}\to \phi {\mu}^{+}{\nu}_{\mu}\right)}{\mathcal{B}\left({D}_s^{+}\to \phi {e}^{+}{\nu}_e\right)}=0.94\pm 0.08 $$
B
D
s
+
→
ϕ
μ
+
ν
μ
B
D
s
+
→
ϕ
e
+
ν
e
=
0.94
±
0.08
, in agreement with lepton universality. By performing a partial wave analysis, the hadronic form factor ratios at
q
2
= 0 are extracted, finding
$$ {r}_V=\frac{V(0)}{A_1(0)}=1.58\pm 0.17\pm 0.02 $$
r
V
=
V
0
A
1
0
=
1.58
±
0.17
±
0.02
and
$$ {r}_2=\frac{A_2(0)}{A_1(0)}=0.71\pm 0.14\pm 0.02 $$
r
2
=
A
2
0
A
1
0
=
0.71
±
0.14
±
0.02
, where the first uncertainties are statistical and the second are systematic. No significant
S
-wave contribution from
f
0
(980)
→ K
+
K
−
is found. The upper limit
$$ \mathcal{B}\left({D}_s^{+}\to {f}_0(980){\mu}^{+}{\nu}_{\mu}\right)\cdot \mathcal{B}\left({f}_0(980)\to {K}^{+}{K}^{-}\right)<5.45\times {10}^{-4} $$
B
D
s
+
→
f
0
980
μ
+
ν
μ
⋅
B
f
0
980
→
K
+
K
−
<
5.45
×
10
−
4
is set at 90% credibility level.
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