A
bstract
We present the study of the decay
J/ψ
→
ρπ
. The results are based on of 5.2 million
J/ψ
events collected by the KEDR detector at the VEPP-4M collider. The branching fractions are measured ...to be
B
(
J/ψ
→
ρπ
) = (2
.
072 ± 0
.
017 ± 0
.
062) ∙ 10
−
2
and
B
(
J/ψ
→
π
+
π
−
π
0
) = (1
.
878 ± 0
.
013 ± 0
.
051) ∙ 10
−
2
, where the first uncertainties are statistical and the second systematic. Our results are more precise than the previous relative measurements.
Abstract
Using the 1.32
$$\hbox {pb}^{-1}$$
pb
-
1
statistics collected at the
$$J/\psi $$
J
/
ψ
peak with the KEDR detector at the VEPP-4M
$$e^{+}e^{-\, }$$
e
+
e
-
collider, we measured the ...branching fractions of
$$J/\psi $$
J
/
ψ
meson decays to the final states 2(
$$\pi ^{+}\pi ^{-})\pi ^{0}$$
π
+
π
-
)
π
0
,
$$K^{+}K^{-}\pi ^{+}\pi ^{-}\pi ^{0}$$
K
+
K
-
π
+
π
-
π
0
, 2(
$$\pi ^{+}\pi ^{-})$$
π
+
π
-
)
and
$$K^{+}K^{-}\pi ^{+}\pi ^{-}$$
K
+
K
-
π
+
π
-
. The results obtained for the decays
$$J/\psi \rightarrow $$
J
/
ψ
→
2(
$$\pi ^{+}\pi ^{-})\pi ^{0}$$
π
+
π
-
)
π
0
,
$$J/\psi \rightarrow K^{+}K^{-}\pi ^{+}\pi ^{-}\pi ^{0}$$
J
/
ψ
→
K
+
K
-
π
+
π
-
π
0
contradict the measurements performed by other groups in the last century, but agree well with recent results of BABAR and BESIII collaborations.
Variations in magnetic properties of the heavy-fermion YbNi
2
alloy when milled in a high energy ball milling system have been investigated. The ferromagnetic transition (
T
C
= 10.4 K) in the ...initial sample almost vanishes after milling, which leads to the appearance of a magnetic transition at
T
* = 3.2 K in nanocrystallites. Before milling, processes of spin–lattice relaxation of the Orbach–Aminov type with the participation of the first excited Stark sublevel of the Yb
3+
ion located at 75 K are dominating in the electron spin dynamics in the paramagnetic phase of the alloy. A comparative study of the temperature dependence of the magnetic properties and spectra of electron paramagnetic resonance in poly- and nanocrystalline samples indicates the existence of a magnetic inhomogeneity of the compound arising upon milling.
Using the 1.32
pb
-
1
statistics collected at the
J
/
ψ
peak with the KEDR detector at the VEPP-4M
e
+
e
-
collider, we measured the branching fractions of
J
/
ψ
meson decays to the final states 2(
π
...+
π
-
)
π
0
,
K
+
K
-
π
+
π
-
π
0
, 2(
π
+
π
-
)
and
K
+
K
-
π
+
π
-
. The results obtained for the decays
J
/
ψ
→
2(
π
+
π
-
)
π
0
,
J
/
ψ
→
K
+
K
-
π
+
π
-
π
0
contradict the measurements performed by other groups in the last century, but agree well with recent results of BABAR and BESIII collaborations.
—
The review presents the experiments performed with the KEDR detector at the
collider VEPP-4M in the energy range of
= 1.84–3.88 GeV. The cross section of
annihilation to hadrons was measured at 22 ...points of this range and the search for narrow resonances was conducted below 3.1 GeV. The masses of
and
mesons were measured with a record accuracy better than
; their partial and total widths were determined. Measurements of the tau lepton mass and masses of charged and neutral
mesons were performed with high precision. The measurements of the
parameters are discussed, and attention is drawn to some inconsistency of the procedure employed by the Particle Data Group for determining its parameters.
The elemental composition of Ge–Se glasses prepared by different methods and the distribution of Ge and Se along the bulk sample length are investigated by inductively coupled plasma atomic emission ...spectrometry. The estimated uncertainty of Ge and Se content measurement is 0.02–0.05 at.% (P = 0.95). To date, these results are the most accurate for determining the elemental composition of optical Ge-based chalcogenides. The minimum required mass of the analyzed glass samples does not exceed 1 mg. Partial phase separation in the Ge–Se system leads to a significant (±2 at.%) deviation of the chemical composition of Ge–Se glasses along the length of the bulk sample from the specified value. This is the first time that the elemental composition of single-index Ge–Se fibers along the fiber length has been studied. The rod drawing method allows the fabrication of optical fibers with composition deviation along the length of 0.03–0.05 at.%. In the case of drawing by the crucible method, the deviations of the fiber composition can reach 0.16 at.% compared with the initial glass sample.
•A technique has been developed for determining the elemental composition of Ge-Se glasses and optical fibers by ICP-AES.•The analysis results accuracy is characterized by expanded uncertainty of 0.02–0.05 at.% (P = 0.95).•The chemical composition of glassy samples of Ge-Se systems and optical fibers depends on the preparation method.
Glasses of Ge25-xGaxTe75-yIy system with gallium content of 5–15 at.% and iodine of 0–6 at.% have been prepared. The glass transition temperature, crystallization and melting temperature of the ...samples in the range 100–400 °C were determined by differential scanning calorimetry. In Ge15Ga10Te75-yIy system, the crystallization stability of glasses is extremely dependent on composition, taking the maximum value for y = 2; for Ge10Ga15Te75-yIy and Ge25-xGaxTe69I6 systems, a monotonous increase in the resistance to crystallization with an increase in the content of iodine and gallium is characteristic. The density of the glasses, measured by the hydrostatic weighing method, decreases with increasing of y. In view of physicochemical and optical properties among the investigated samples, the glasses of Ge15Ga10Te73I2 and Ge10Ga15Te69I6 are the most suitable for drawing optical fiber. Optical fibers are manufactured from these glasses by crucible method.
•In Ge15Ga10Te75-yIy system, the crystallization stability of glasses is extremely dependent on composition, taking the maximum value for y = 2;•For Ge10Ga15Te75-yIy system a monotonous increase in the resistance to crystallization with an increase in the content of I is characteristic.•The glasses of Ge15Ga10Te73I2 and Ge10Ga15Te69I6 are the most suitable for drawing optical fiber.
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