A
bstract
Utilizing 7
.
33 fb
−
1
of
e
+
e
−
collision data taken at the center-of-mass energies of 4.128, 4.157, 4.178, 4.189, 4.199, 4.209, 4.219, and 4.226 GeV with the BESIII detector, the ...branching fraction of the leptonic decay
$$ {D}_s^{+} $$
D
s
+
→ τ
+
ν
τ
via
τ
+
→ μ
+
ν
μ
$$ \overline{\nu} $$
ν
¯
τ
is measured to be
$$ {\mathcal{B}}_{D_s^{+}\to {\tau}^{+}{\nu}_{\tau }} $$
B
D
s
+
→
τ
+
ν
τ
= (5
.
37
±
0
.
17
stat
±
0
.
15
syst
)%. Combining this branching fraction with the world averages of the measurements of the masses of
τ
+
and
$$ {D}_s^{+} $$
D
s
+
as well as the lifetime of
$$ {D}_s^{+} $$
D
s
+
, we extract the product of the decay constant of
$$ {D}_s^{+} $$
D
s
+
and the
c → s
Cabibbo-Kobayashi-Maskawa matrix element to be
$$ {f}_{D_s^{+}} $$
f
D
s
+
|V
cs
|
= (246
.
7
±
3
.
9
stat
±
3
.
6
syst
) MeV. Taking
|V
cs
|
from a global fit in the standard model we obtain
$$ {f}_{D_s^{+}} $$
f
D
s
+
= (253
.
4
±
4
.
0
stat
±
3
.
7
syst
) MeV. Conversely, taking
$$ {f}_{D_s^{+}} $$
f
D
s
+
from lattice quantum chromodynamics calculations, we obtain
|V
cs
|
= 0
.
987
±
0
.
016
stat
±
0
.
014
syst
.
A
bstract
Based on 4.5 fb
−
1
data taken at seven center-of-mass energies ranging from 4.600 to 4.699 GeV with the BESIII detector at the BEPCII collider, we measure the branching fractions of
$$ ...{\Lambda}_c^{+} $$
Λ
c
+
→
Σ
+
+
hadrons
relative to
$$ {\Lambda}_c^{+} $$
Λ
c
+
→
Σ
+
π
+
π
−
. Combining with the world average branching fraction of
$$ {\Lambda}_c^{+} $$
Λ
c
+
→
Σ
+
π
+
π
−
, their branching fractions are measured to be (0
.
377
±
0
.
042
±
0
.
020
±
0
.
021)% for
$$ {\Lambda}_c^{+} $$
Λ
c
+
→
Σ
+
K
+
K
−
, (0
.
200
±
0
.
023
±
0
.
011
±
0
.
011)% for
$$ {\Lambda}_c^{+} $$
Λ
c
+
→
Σ
+
K
+
π
−
, (0
.
414
±
0
.
080
±
0
.
030
±
0
.
023)% for
$$ {\Lambda}_c^{+} $$
Λ
c
+
→
Σ
+
ϕ
and (0
.
197
±
0
.
036
±
0
.
009
±
0
.
011)% for
$$ {\Lambda}_c^{+} $$
Λ
c
+
→ Σ
+
K
+
K
−
(non-
ϕ
). In all the above results, the first uncertainties are statistical, the second are systematic and the third are from external input of the branching fraction of
$$ {\Lambda}_c^{+} $$
Λ
c
+
→
Σ
+
π
+
π
−
. Since no signal for
$$ {\Lambda}_c^{+} $$
Λ
c
+
→
Σ
+
K
+
π
−
π
0
is observed, the upper limit of its branching fraction is determined to be 0.13% at the 90% confidence level.
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.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
The singly Cabibbo-suppressed decay Lambda(+)(c) -> n pi(+) e is observed for the first time with a statistical significance of 7.3 sigma by using 3.9 fb(-1) of e(+)e(-) collision data collected ...at center-of-mass energies between 4.612 and 4.699 GeV with the BESIII detector at BEPCII. The branching fraction of Lambda(+)(c) -> n pi(+) is measured to be (6.6 +/- 1.2(stat) 0.4(syst)) x 10(-4). By taking the upper limit of branching fractions of Lambda(+)(c) -> n pi(+) from the Belle experiment, the ratio of branching fractions between Lambda(+)(c) -> n pi(+) and Lambda(+)(c) -> p pi(0) is calculated to be larger than 7.2 at the 90% confidence level, which disagrees with most predictions of the available phenomenological models. In addition, the branching fractions of the Cabibbo-favored decays Lambda(+)(c) -> Lambda pi(+) and Lambda(+)(c)-> Sigma(0)(pi+) are measured to be (1.31 +/- 0.08(stat) +/- 0.05(syst)) x 10(-2) and (1.22 +/- 0.08(stat) +/- 0.07(syst)) x 10(-2), respectively, which are consistent with previous results.
Using 4.5 fb-1 of e+e- annihilation data samples collected at center-of-mass energies ranging from 4.600 to 4.698 GeV with the BESIII detector at the BEPCII collider, we measured the absolute ...branching fraction for the inclusive semileptonic decay A+c -Xe+ve, where X refers to any possible particle system. The branching fraction of the decay is determined to be B(A+c -Xe+ve) = (4.06 +/- 0.10stat +/- 0.09syst)%. Our result improves the precision of previous measurements of B(A+c -Xe+ve) by more than threefold. Using the known A+c lifetime and the charge-averaged semileptonic decay width of nonstrange charmed mesons, we measure the ratio of inclusive semileptonic decay widths Gamma(A+c -Xe+ve)/Gamma over bar (D -Xe+ve) = 1.28 +/- 0.05, where statistical and systematic uncertainties are combined.
Based on a data sample of (2712.4±14.3)×10 6 ψ(3686) events collected with the BESIII detector at the BEPCII collider, the M1 transition ψ(3686)→γη c (2S) with η c( 2S)→K¯Kπ is studied, where K¯Kπ is ...K + K − π 0 or K 0 S K ± π ∓ . The mass and width of the η c (2S) are measured to be (3637.8±0.8(stat)±0.2(syst)) MeV/c 2 and (10.5±1.7(stat)±3.5(syst)) MeV, respectively. The product branching fraction B(ψ(3686)→γη c (2S))×B(η c (2S)→K¯Kπ) is determined to be (0.97±0.06(stat)±0.09(syst))×10 −5 . Using B(η c (2S)→K¯Kπ)=(1.86 +0.68 −0.49 )%, we obtain the branching fraction of the radiative transition to be B(ψ(3686)→γη c (2S))=(5.2±0.3(stat)±0.5(syst) +1.9 −1.4 (extr))×10 −4 , where the third uncertainty is due to the quoted B(η c (2S)→K¯Kπ).
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.
By analyzing e+e- annihilation data corresponding to an integrated luminosity of 2.93 fb-1 collected at the center-of-mass energy of 3.773 GeV with the BESIII detector, we report the first ...observations of the doubly Cabibbo-suppressed decays D+ → K+π0π0 and D+ → K+π0η. The branching fractions of D+ → K+π0π0 and D+ → K+π0η are measured to be (2.1 ± 0.4stat ± 0.1syst) x 10-4 and (2.1 ± 0.5stat ± 0.1syst) x 10-4 with statistical significances of 8.8σ and 5.5σ, respectively. In addition, we search for the subprocesses D+ → K*(892)+π0 and D+ → K*(892)+η with K*(892)+ → K+π0. The branching fraction of D+ → K*(892)+η is determined to be (4.4$^{+1.8}_{-1.5stat}$ ± 0.2syst) x 10-4, with a statistical significance of 3.2σ. No significant signal for D+ → K*(892)+π0 is found and we set an upper limit on the branching fraction of this decay at the 90% confidence level to be 5.4 x 10-4.
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