Study of K+→π0e+νγ decay with OKA setup Polyarush, A. Yu; Akimenko, S. A.; Artamonov, A. V. ...
The European physical journal. C, Particles and fields,
02/2021, Letnik:
81, Številka:
2
Journal Article
Recenzirano
Odprti dostop
Results of a study of the
K
+
→
π
0
e
+
ν
γ
decay at OKA setup are presented. More than 32,000 events of this decay are observed. The differential spectra over the photon energy and the ...photon–electron opening angle in kaon rest frame are presented. The branching ratios, normalized to that of
K
e
3
decay are calculated for different cuts on
E
γ
∗
and
c
o
s
Θ
e
γ
∗
. In particular, the branching ratio for
E
γ
∗
>
30
MeV and
Θ
e
γ
∗
>
20
∘
is measured R =
B
r
(
K
+
→
π
0
e
+
ν
e
γ
)
B
r
(
K
+
→
π
0
e
+
ν
e
)
= = (0.587±0.010(
stat
.)±0.015(
syst
.))
×
10
-
2
, which is in a good agreement with ChPT
O
(
p
4
)
calculations.
The
T
-odd correlation
, which is the mixed product of the momenta of
,
, and γ in the system of rest of the kaon divided by
, has been measured in the
K
+
→ π
0
e
+
ν
e
γ radiative decay among 101 ...200 candidate events detected at the OKA setup. The asymmetry of the distribution in
is characterized by the ratio
, where
is the number of events with positive (negative) ξ. The value
= (+0.1 ± 3.9(stat.) ± 1.7(syst.)) × 10
–3
or
(90% C.L.) has been obtained.
Abstract A high statistics data sample of the decays of $$K^+$$ K+ mesons to three charged particles was accumulated by the OKA experiment in 2012 and 2013. This allowed to select a clean sample of ...about 450 events with $$K^{+}\rightarrow \pi ^{+}\pi ^{-}\pi ^{+}\gamma $$ K+→π+π-π+γ decays with the energy of the photon in the kaon rest frame greater than 30 MeV. The measured branching fraction of the $$K^{+}\rightarrow \pi ^{+}\pi ^{-}\pi ^{+}\gamma $$ K+→π+π-π+γ , with $$E_{\gamma }^{*} > 30\ \hbox {MeV}$$ Eγ∗>30MeV is equal to $$(0.71 \pm 0.05) \times 10^{-5}$$ (0.71±0.05)×10-5 . The measured differential branching fraction over photon energy is compared with the prediction of the chiral perturbation theory to $${\mathcal {O}}(p^{4})$$ O(p4) . A search for an up-down asymmetry of the photon with respect to the hadronic system decay plane is also performed.
On the statistics of ~1.7 × 10
8
interactions of positively charged kaons on copper nuclei, coherent events of the
K
+
π
0
system production are selected. The cross sections for the Coulomb and ...coherent strong components and their interference in the region of the
K
*(892) meson are measured. The partial width for the decay
K
*(892) →
K
+
γ is determined. When studying the mass spectrum of the
K
+
π
0
system, an effect which can be interpreted as the interference of the chiral anomaly and the
K
*(892)
s
-channel amplitudes is found. This gives an estimate for the ratio of the observed amplitude of the chiral anomaly to the theoretical one:
A
exp
/
A
th
= 0.9 ± 0.24(stat.) ± 0.3(syst.).
Abstract A high statistics data sample of the $$K^{+}\rightarrow \mu ^{+}\nu _{\mu }$$ K+→μ+νμ decay was accumulated by the OKA experiment in 2012. The missing mass analysis was performed to search ...for the decay channel $$K^{+}\rightarrow \mu ^{+}\nu _{H}$$ K+→μ+νH with a hypothetic stable heavy neutrino in the final state. The obtained missing mass spectrum does not show peaks that could be attributed to existence of stable heavy neutrinos in the mass range $$(270< m_{\nu _{H}} < 375)$$ (270<mνH<375) MeV$$/c^{2}$$ /c2 . As a result, upper limits on the branching ratio and on the value of the mixing element $$|U_{\mu H}|^{2}$$ |UμH|2 are obtained.
Search for heavy neutrino in K+→μ+νH decay Sadovsky, A. S.; Kurshetsov, V. F.; Filin, A. P. ...
The European physical journal. C, Particles and fields,
02/2018, Letnik:
78, Številka:
2
Journal Article
Recenzirano
Odprti dostop
A high statistics data sample of the
K
+
→
μ
+
ν
μ
decay was accumulated by the OKA experiment in 2012. The missing mass analysis was performed to search for the decay channel
K
+
→
μ
+
ν
H
with a ...hypothetic stable heavy neutrino in the final state. The obtained missing mass spectrum does not show peaks that could be attributed to existence of stable heavy neutrinos in the mass range
(
270
<
m
ν
H
<
375
)
MeV
/
c
2
. As a result, upper limits on the branching ratio and on the value of the mixing element
|
U
μ
H
|
2
are obtained.
In the process of optimization of heterologous expression of thermostable chemotaxis proteins CheW and CheY as industrially useful polypeptides, their direct influence on the cell growth kinetics and ...morphology of
Escherichia coli
was observed. CheW and CheY of bacteria of the genus
Thermotoga
, being expressed in recombinant form in
E. coli
cells, are involved in the corresponding signal pathways of the mesophilic microorganisms. The effects of such involvement in the metabolism of “host” cells are extremely diverse: from rapid aging of the culture to elongation of the stationary growth phase. We also discuss the mechanisms of the influence of the heterologous chemotaxis proteins on cells, their positive and negative effects, as well as potential applications in industry and biomedicine.
The article discusses the applicability of the theory of disasters and nonlinear dynamics in predicting the systemic risks of managing the digital economy and Internet of things systems. One of the ...approaches may be modeling of nonlinear processes based on the use of the concepts of catastrophe theory. Studies have shown a key indicator of such modeling is to determine the essential features of the disaster. The study showed that the widely used models of the economic processes of the digital economy, as well as the software and technical components of the internet of things, can be transformed into the canonical equation of «assembly», which subsequently leads to the emergence of such an area in the space of phase development variables in which jumps can occur or for the better, or vice versa, such as a collapse. Currently, in the digital economy, the study of such phenomena seems to be very relevant, since an uncontrolled «spasmodic» change in the functioning parameters of such systems can lead to disastrous consequences for the functioning of all interconnected subsystems. The collapse or unstable behavior of one of the components of such systems can lead to the collapse of the entire system. Such phenomena are not allowed in the digital economy and can trigger not only economic consequences, but also social ones.
The work is devoted to one of the aspects related to the resolution of disputes over the boundaries of land plots. Recently, the number of these disputes has been steadily growing, which confirms the ...relevance of the chosen topic. Border disputes are currently resolved only through the courts, almost always with a forensic land surveying. The aspect considered in the article concerns the accuracy of constructing models of the objects of surveying, since software products used do not have documentary evidence of the accuracy of the created models. Therefore, experts need to independently test the models for accuracy. Moreover, such tests make it possible to reveal expert errors at the modeling stage. The paper proposes the authors’ method of testing for the accuracy of a computer-graphic model of objects, studied by a forensic land surveying.
Films with amorphous structure are grown by magnetron sputtering of La
0.7
Sr
0.3
MnO
3
targets. The clusterization kinetics of magnetron plasma in the flow of interacting particles with the initial ...formation of local atomic configurations of the pre-cluster level (the first clusterization stage) followed by flow deposition on an extended glassy substrate (the second stage of different-scale cluster formation). It is shown that the nonmonotonicity in variations of the atomic order and sample properties with increasing distance from the target is caused by different-valence manganese ions in the flow and their spatial modulation by an ion-acoustic wave. It is found that Mn
3+
and Mn
4+
ions are contained in fragments of (
)–R, (203)–R, (212)–O, (003)–O planes belonging to different-scale clusters.
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