Lithium isotope compositions were determined for synthetic calcite and fluid, reported in Füger et al. (2019). Calcite was precipitated at 25 °C, and mineral growth rate and pH varied within the ...range of 10−8.1 ≤ rp (mol m−2 s−1) ≤ 10−7.2 and 6.3 ≤ pH ≤ 9.5, respectively. At pH = 8.25 ± 0.15, the Δ7Licalcite-fluid = δ7Licalcite - δ7Lifluid value of −2.76 ± 0.22‰ (n = 4) was yielded when calcite growth rate was lower than ∼ 10−7.7 (mol m−2 s−1). As calcite growth rate increased, Δ7Licalcite-fluid values progressively decreased to about −4.5‰. The dependence of Li isotope fractionation on calcite growth rate is described by the surface reaction kinetic model developed by DePaolo (2011). In this model the equilibrium and kinetic isotope fractionation factors obtain values of −2.7 ± 0.1‰ and −8.8 ± 0.1‰, respectively. In addition, for experiments performed under similar surface-normalized growth rate of 10−7.7±0.2 (mol m−2 s−1) a significant decrease in Δ7Licalcite-fluid from pH 9.5 to 6.3 was observed. These variations of Δ7Licalcite-fluid as a function of pH for experiments performed under low degrees of solution saturation with respect to calcite point towards the incorporation of two or more Li-bearing species in the solid phase. Thus, the Li isotope composition of the solid reflects the abundance of these species, which depends on solution pH and fluid composition.
Overall the results of this study suggest that both calcite growth rate and pH are parameters that can significantly affect the measured Li isotope fractionation between calcite and fluid. The high sensitivity of Δ7Licalcite-fluid to calcite growth rate observed in this study suggests that a high variability of δ7Licalcite in natural samples, such as foraminifera, brachiopods, and speleothems can be expected in natural environments. The implications for the potential use of elemental and isotope fractionation of Li during calcite formation are discussed in the light of reconstruction of paleo-environmental conditions.
A massless particle beyond the Standard Model is searched for in the two-body decay Σ+→p+invisible using (1.0087±0.0044)×1010J/ψ events collected at a center-of-mass energy of s=3.097GeV with the ...BESIII detector at the BEPCII collider. No significant signal is observed, and the upper limit on the branching fraction B(Σ+→p+invisible) is determined to be 3.2×10−5 at the 90% confidence level. This is the first search for a flavor-changing neutral current process with missing energy in hyperon decays which plays an important role in constraining new physics models.
The spin and parity of the charmed mesons Ds⁎+, D⁎0 and D⁎+ are determined for the first time to be JP=1− with significances greater than 10σ over other hypotheses of 2+ and 3−, using an e+e− ...collision data sample with an integrated luminosity of 3.19 fb−1 collected by the BESIII detector at a center-of-mass energy of 4.178 GeV. Different spin-parity hypotheses are tested via a helicity amplitude analysis of the processes e+e−→Ds⁎+Ds−, D⁎0D0 and D⁎+D−, with Ds⁎+→Ds+γ, D⁎0→D0π0, and D⁎+→D+π0. The results confirm the quark model predictions.
A
bstract
The Born cross sections of the
e
+
e
−
→ D
*+
D
*
−
and
e
+
e
−
→ D
*+
D
−
processes are measured using
e
+
e
−
collision data collected with the BESIII experiment at center-of-mass ...energies from 4.085 to 4.600 GeV, corresponding to an integrated luminosity of 15
.
7 fb
−
1
. The results are consistent with and more precise than the previous measurements by the Belle, Babar and CLEO collaborations. The measurements are essential for understanding the nature of vector charmonium and charmonium-like states.
A
bstract
Using 15
.
6 fb
−
1
of
e
+
e
−
collision data collected at twenty-four center-of-mass energies from 4
.
0 to 4
.
6 GeV with the BESIII detector, the helicity amplitudes of the process
e
+
e
...−
→
π
+
π
−
ω
are analyzed for the first time. Born cross section measurements of two-body intermediate resonance states with statistical significance greater than 5
σ
are presented, such as
f
0
(500),
f
0
(980),
f
2
(1270),
f
0
(1370),
b
1
(1235)
±
, and
ρ
(1450)
±
. In addition, evidence of a resonance state in
e
+
e
−
→
π
+
π
−
ω
production is found. The mass of this state obtained by line shape fitting is about 4
.
2 GeV/
c
2
, which is consistent with the production of
ψ
(4160) or
Y
(4220).
Helicity amplitude analysis of χcJ→ ϕϕ Balossino, I.; Bettoni, D.; Chen, G. ...
The journal of high energy physics,
05/2023, Letnik:
2023, Številka:
5
Journal Article
Recenzirano
Odprti dostop
A
bstract
Using (447.9
±
2.3) million
ψ
(3686) events collected with the BESIII detector, the decays of
χ
cJ
→ ϕϕ
(
J
= 0
,
1
,
2) have been studied via the decay
ψ
(3686)
→ γχ
cJ
. The branching ...fractions of the decays
χ
cJ
→ ϕϕ
(
J
= 0
,
1
,
2) are determined to be (8
.
59 ± 0
.
27 ± 0
.
20) × 10
−
4
, (4
.
26 ± 0
.
13 ± 0
.
15) × 10
−
4
, and (12
.
67 ± 0
.
28 ± 0
.
33) × 10
−
4
, respectively, which are the most precise measurements to date. From a helicity amplitude analysis of the process
ψ
(3686)
→ γχ
cJ
, χ
cJ
→ ϕϕ, ϕ → K
+
K
−
, the polarization parameters of the
χ
cJ
→ ϕϕ
decays are determined for the first time.
A
bstract
Using (448
.
1
±
2
.
9)
×
10
6
ψ
(3686) events collected with the BESIII detector at the BEPCII collider, the decay
ψ
(3686)
→
Σ
−
Σ
¯
+
is observed for the first time with a branching ...fraction of (2
.
82
±
0
.
04
stat
.
±
0
.
08
syst
.
)
×
10
−
4
, and the angular parameter
α
Σ
−
is measured to be 0
.
96
±
0
.
09
stat
.
±
0
.
03
syst
.
.
A
bstract
Using data samples with an integrated luminosity of 19 fb
−
1
at twenty-eight center-of-mass energies from 3.872 GeV to 4.700 GeV collected with the BESIII detector at the BEPCII ...electron-positron collider, the process
e
+
e
−
→
ηπ
+
π
−
and the intermediate process
e
+
e
−
→
ηρ
0
are studied for the first time. The Born cross sections are measured. No significant resonance structure is observed in the cross section lineshape.
The Born cross sections of e+e−→Σ0Σ¯0 are measured at center-of-mass energies from 2.3864 to 3.0200 GeV using data samples with an integrated luminosity of 328.5 pb−1 collected with the BESIII ...detector operating at the BEPCII collider. The analysis makes use of a novel reconstruction method for energies near production threshold, while a single-tag method is employed at other center-of-mass energies. The measured cross sections are consistent with earlier results from BaBar, with a substantially improved precision. The cross-section lineshape can be well described by a perturbative QCD-driven energy function. In addition, the effective form factors of the Σ0 baryon are determined. The results provide precise experimental input for testing various theoretical predictions.
