A high-statistics data sample of the
K
+
decays is recorded by the OKA collaboration. A missing mass analysis is performed to search for a light invisible pseudoscalar axion-like particle (ALP)
a
in ...the decay
K
+
→
π
+
π
0
a
. No signal is observed, and the upper limits for the branching ratio of the decay are calculated. The
90
%
confidence level upper limit changes from
2.5
·
10
-
6
to
2
·
10
-
7
for the ALP mass from 0 to 200 MeV/
c
2
, except for the region of
π
0
mass, where the upper limit is
4.4
·
10
-
6
.
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.
Anorectal abnormalities are among the most common congenital malformations in children requiring emergency surgical interventions.The objective is to analyze existing domestic and foreign ...publications on the features of anesthesia in anorectal abnormalities in children.Subjects and Methods. The search for publications was carried out in the abstract bases of Russian Scientific Citation Index, PubMed and Scopus according to the key words: anorectal abnormalities, anesthesia, regional anesthesia, children. 105 publications were found, 49 studies were selected for analysis.Results. For the purpose of anesthesia, both general and regional anesthesia are used to correct anorectal anomalies. Among regional techniques, spinal and caudal anesthesia is most often used. The most effective anesthesia option for anorectal surgery is saddle anesthesia since it is accompanied by a significant decrease in the tone of the anal sphincter. Combined use of general anesthesia and caudal analgesia contributes to the reduction of intraoperative blood loss and early restoration of bowel functions.Conclusion. Further research is needed to establish rapid post-operative recovery protocols for anorectal malformations in children.
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.
A precise measurement of the vector and axial-vector form factors difference Formula omitted in the Formula omitted decay is presented. About 95K events of Formula omitted are selected in the OKA ...experiment. The result is Formula omitted. Both errors are smaller than in the previous Formula omitted measurements.
A high statistics data sample of the decays of Formula omitted 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 Formula omitted decays with the energy of the photon in the kaon rest frame greater than 30 MeV. The measured branching fraction of the Formula omitted, with Formula omitted is equal to Formula omitted. The measured differential branching fraction over photon energy is compared with the prediction of the chiral perturbation theory to Formula omitted. A search for an up-down asymmetry of the photon with respect to the hadronic system decay plane is also performed.
Abstract A high-statistics data sample of the $$K^{+}$$ K + decays is recorded by the OKA collaboration. A missing mass analysis is performed to search for a light invisible pseudoscalar axion-like ...particle (ALP) a in the decay $$K^{+} \rightarrow \pi ^{+} \pi ^{0} a$$ K + → π + π 0 a . No signal is observed, and the upper limits for the branching ratio of the decay are calculated. The $$90\%$$ 90 % confidence level upper limit changes from $$2.5\cdot 10^{-6}$$ 2.5 · 10 - 6 to $$2\cdot 10^{-7}$$ 2 · 10 - 7 for the ALP mass from 0 to 200 MeV/ $$c^{2}$$ c 2 , except for the region of $$\pi ^{0}$$ π 0 mass, where the upper limit is $$4.4\cdot 10^{-6}$$ 4.4 · 10 - 6 .
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.
Study of [Formula omitted] 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
Results of a study of the Formula omitted 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 Formula omitted decay are calculated for different cuts on Formula omitted and Formula omitted. In particular, the branching ratio for Formula omitted MeV and Formula omitted is measured R = Formula omitted = = (0.587±0.010(stat.)±0.015(syst.)) Formula omitted, which is in a good agreement with ChPT Formula omitted calculations.
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.).
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