The cross section of the process e + e − → π + π − has been measured in the center of mass energy range from 0.32 to 1.2 GeV with the CMD-3 detector at the electron-positron collider VEPP-2000. The ...measurement is based on a full dataset collected below 1 GeV during three data taking seasons, corresponding to an integrated luminosity of about 62 pb − 1 . In the dominant ρ -resonance region, a systematic uncertainty of 0.7% has been reached. At energies around ϕ -resonance the π + π − production cross section was measured for the first time with high beam energy resolution. The forward-backward charge asymmetry in the π + π − production has also been measured. It shows a strong deviation from the theoretical prediction based on the conventional scalar quantum electrodynamics framework, and it is in good agreement with the generalized vector-meson-dominance and dispersive-based predictions. The impact of the presented results on the evaluation of the hadronic contribution to the anomalous magnetic moment of muon is discussed. Published by the American Physical Society 2024
The paper describes a method of the charged particle identification, developed for the CMD-3 detector, installed at the VEPP-2000 e+e− collider. The method is based on application of boosted decision ...trees classifiers, trained for the optimal separation of electrons, muons, pions and kaons in the momentum range from 100 to 1200MeV/c. The input variables for the classifiers are linear combinations of the energy depositions of charged particles in 12 layers of the liquid xenon calorimeter of the CMD-3. The event samples for training of the classifiers are taken from the simulation. Various issues of the calorimeter strip channels response simulation and their calibration are considered. Application of the method is illustrated by the examples of separation of the e+e−(γ) and π+π−(γ) final states and of selection of the K+K− final state at high energies.
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.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Human iris color was one of the first traits for which Mendelian segregation was established. To date, the genetics of iris color is still not fully understood and is of interest, particularly in ...view of forensic applications. In three independent genome-wide association (GWA) studies of a total of 1406 persons and a genome-wide linkage study of 1292 relatives, all from the Netherlands, we found that the 15q13.1 region is the predominant region involved in human iris color. There were no other regions showing consistent genome-wide evidence for association and linkage to iris color. Single nucleotide polymorphisms (SNPs) in the
HERC2 gene and, to a lesser extent, in the neighboring
OCA2 gene were independently associated to iris color variation.
OCA2 has been implicated in iris color previously. A replication study within two populations confirmed that the
HERC2 gene is a new and significant determinant of human iris color variation, in addition to
OCA2. Furthermore,
HERC2 rs916977 showed a clinal allele distribution across 23 European populations, which was significantly correlated to iris color variation. We suggest that genetic variants regulating expression of the
OCA2 gene exist in the
HERC2 gene or, alternatively, within the 11.7 kb of sequence between
OCA2 and
HERC2, and that most iris color variation in Europeans is explained by those two genes. Testing markers in the
HERC2-OCA2 region may be useful in forensic applications to predict eye color phenotypes of unknown persons of European genetic origin.
A recent result of the cross section measurement of the process e + e − → K S K π at e + e − collider VEPP-2000 is presented using a data sample of the ∼150 pb−1 integrated luminosity collected with ...the CMD-3 detector. The processes with charged kaons in multi hadron events attract special interest, because they impact strongly on studies of light quark hadronization, isospin symmetry, and strange meson spectroscopy. Experimental results of e + e − → K S K π cross section are presented in a broad energy range covered by the VEPP-2000 and compared to earlier measurements. A study of the production dynamics confirms the dominance of neutral KK * ( 892 ) intermediate state.
A unique instrumentation complex that includes wigglers, X-ray position sensitive detectors, diffractometers, and explosion chambers and enables a 73 ps X-ray diffraction time resolution (exposure ...time) has been developed at the Siberian Synchrotron and Terahertz Radiation Center, a research collaboration operating at the Budker Institute of Nuclear Physics, Siberian Branch of the Russian Academy of Sciences. A number of techniques have been developed and implemented with which nanosecond-resolution investigations of the nucleation and growth dynamics became possible for the first time for diamond and metal nanoparticles under explosion and shock wave conditions. Studies with millisecond resolution of the structural transformation dynamics of chemical reactions, investigations of the kinetics of self-propagating high-temperature synthesis, and obtaining information on the state of catalysts are also among the new possibilities developed.
The electronic width of the
J
/
ψ
meson and its product by the branching fractions of
J
/
ψ
meson decay to hadrons and electrons measured with the KEDR detector at the VEPP-4M
e
+
e
−
collider have ...been reported in ref. 1.
Although the vertical cup-disc ratio (VCDR) and intraocular pressure (IOP) are important determinants of open angle glaucoma (OAG), it is unclear to what extent the genetic origin of these traits ...overlap with those of OAG. We evaluated whether the same genes that determine VCDR and IOP also predict OAG.
Genetic risk scores were constructed from single nucleotide polymorphisms (SNPs) using genome wide association data of 9326 participants from the Rotterdam Study cohorts (mean ± SD age: 64.6 ± 9.1 years). These risk scores were used to calculate the explained variance of VCDR and IOP in an independent cohort (Erasmus Rucphen Family study) consisting of 1646 participants (mean ± SD age: 46.8 ± 14.1 years) and the OAG risk in a subset of the Rotterdam Study cohorts. To evaluate false positive findings, we generated two new variables containing randomly sampled values to serve as a negative control.
The explained variance of VCDR increased when increasing the number of SNPs included in the risk score, suggesting a polygenic model. We found no clear evidence for a similar model for IOP, suggesting that a small number of SNPs determine the susceptibility to IOP. The SNPs related to IOP in terms of p values contributed little to VCDR. The risk scores associated with VCDR were also associated significantly with OAG. This suggests a common polygenic background for VCDR and OAG CONCLUSIONS: We found evidence for a polygenic model underlying one of the major traits of OAG, VCDR, and OAG itself. The IOP did not show any evidence for such a model.
The process e+e−→K+K− has been studied using 1.7×106 events from a data sample corresponding to an integrated luminosity of 5.7 pb−1 collected with the CMD-3 detector in the center-of-mass energy ...range 1010–1060 MeV. The cross section is measured with about 2% systematic uncertainty and is used to calculate the contribution to the anomalous magnetic moment of the muon aμK+K−=(19.33±0.40)×10−10, and to obtain the ϕ(1020) meson parameters. We consider the relationship between the e+e−→K+K− and e+e−→KS0KL0 cross sections and compare it to the theoretical prediction.
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