Observation of K+→π+π0π0γ decay Artamonov, A. V.; Bychkov, V. N.; Donskov, S. V. ...
The European physical journal. C, Particles and fields,
04/2024, Letnik:
84, Številka:
4
Journal Article
Recenzirano
Odprti dostop
The
K
+
→
π
+
π
0
π
0
γ
decay is observed by the OKA collaboration. About 60 events of the decay observed with signal:noise
≈
1
. The branching ratio obtained by normalization to
K
+
→
π
+
π
0
π
0
is ...measured to be
(
3.7
±
0.9
(
s
t
a
t
)
±
0.3
(
s
y
s
t
)
)
×
10
-
6
for
E
γ
∗
>
10
MeV
. The branching ratio,
γ
energy spectrum and angular distribution are consistent with ChPT prediction.
Celotno besedilo
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DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
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
.
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DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
We retrieve ionization rates in the atmosphere caused by energetic electron precipitation from balloon observations in the polar atmosphere and compare them against ionization rates recommended for ...the Phase 6 of the Coupled Model Intercomparison Project. In our retrieval procedure, we consider the precipitating electrons with energies from about tens of keV to 5 MeV. Our simulations with 1‐D radiative‐convective model with interactive neutral and ion chemistry show that the difference of the Phase 6 of the Coupled Model Intercomparison Project and balloon‐based ionization rate can lead to underestimation of the NOx enhancement by more than 100% and ozone loss up to 25% in the mesosphere. The atmospheric response is different below 50 km due to considering highly energetic electrons, but it is not important because the absolute values of atmospheric impact is tiny. Ionization rates obtained from the balloon observations reveal a high variability.
Plain Language Summary
The main idea of our manuscript is to demonstrate that the atmospheric ionization rates (IR) can be successfully retrieved from the long‐term balloon observations of the energetic electron precipitation (EEP) events and used to evaluate the uncertainties of the other IR data sets, for example, IR recommended for the Phase 6 of the Coupled Model Intercomparison Project (CMIP6). IR obtained from the balloon observations reveal a high variability. This means that the time resolution used in CMIP6 probably is not enough to consider high frequency variability of the precipitating electron fluxes. Using 1‐D radiative‐convective model with neutral and ion chemistry, we compared the atmospheric response to the one particular EEP observed by balloons and presented in CMIP6 data. We show that the difference of the CMIP6 and balloon‐based IRs can lead to underestimation of the NOx enhancement by more than 100% and ozone loss by up to 25% in the mesosphere. Our results are new and needed for the understanding of the potential uncertainties in CMIP6 EEP forcing. Our paper will give inspiration for the continuation of the balloon measurements of EEP‐related processes using improved instruments.
Key Points
Ionization rates (IR) from energetic electron precipitation (EEP) are calculated using balloon observations and compared to the CMIP6 data set
The difference in the atmospheric response calculated with these two data sets can exceed 100% for NOx and reach 25% for O3
IR obtained from balloon measurements reveal a high temporal variability, which is absent in CMIP6 data
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.
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DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
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.
There is given a construction of a series of semisimple finite-dimensional Hopf algebras having a single irreducible representation of dimension greater than 1. This dimension is equal to the number ...of one-dimensional representations.
Polar regions are the most exposed to secondary particles and radiation produced by primary cosmic rays in the atmosphere, because naturally they are with marginal geomagnetic shielding. In addition, ...the secondary particle flux contributing to the complex radiation field is enhanced at high-mountain altitudes compared to sea level because of the reduced atmospheric attenuation. At present, there are very few systematic experimental measurements of environmental dose at high southern latitudes, specifically at high-altitude region. Here, we report a campaign of measurements with different devices, that is passive and Liulin-type dosimeters, of the radiation background at high-mountain Antarctic station Vostok (3488 m above sea level, 78° 27′ S; 106° 50′ E). We compare the measurements with a Monte Carlo-based model for the propagation of the cosmic rays through the atmosphere and assessment of the radiation field in the atmosphere. We employed the model to estimate the radiation dose at Vostok station during the ground-level enhancement at 28 October 2021. As in previous studies by other teams, we show that the annual dose equivalent at high-altitude Antarctic facilities can significantly exceed the limit of 1 mSv established for the general population by the ICRP.
Display omitted
•Measurement of radiation background at high-altitude Antarctic station Vostok•Comparison with model for propagation of the cosmic rays through the atmosphere•Assessment of the contribution of cosmic rays to radiation during solar proton event•The dose at high-altitude Antarctic stations significantly exceeds the limit of 1 mSv.
Many historians believe that Russia became a great power either as a result of the Poltava victory in 1709, or after the Nystadt Peace of 1721. It is difficult to agree with this. Peter the Great’s ...rule indeed produced a combat-ready regular army, a guard, an officer corps, a navy with shipyards, military bases, and coastal artillery. There was an upsurge in the metallurgical industry and mining. Schools with high-quality military and secular education, the Academy of Sciences, the Senate, and the Synod were established. St. Petersburg was founded. Talented and enterprising individuals were promoted to military, diplomatic and administrative posts. The main factor in the rise of the state was military modernization. The main geopolitical achievement of Peter I was the conquest of full access to the Baltic Sea. However, a limited resource base, military and diplomatic defeats and setbacks did not allow Russia to rise to the rank of a great power. The disasters of Narva in 1700 and on the Prut River in 1711 were painful. Russia lost access to the Sea of Azov, the city of Azov, city of Taganrog, the Azov squadron, shipyards and shipbuilding in the Voronezh Territory were lost. The damage from three treatises with the Ottomans in 1711-1713 was great. Russia has lost all of Zaporozhye. The demarcation of the borders of 1714 threw Russia back several hundred kilometers from the Black Sea region. In 1719, the Russian military force was squeezed out of Central Europe – from Mecklenburg. The sphere of influence of Russia after the victorious Peace of Nystad in 1721 was established only in Northern and Eastern Europe – in the Polish-Lithuanian Commonwealth, the Swedish and Danish-Norwegian kingdom, partly in Prussia. The tsar had no claims to hegemony in Europe and no claims to join the circle of the then great powers. Russia was not a great power like the Habsburg monarchy, France, Great Britain, and the Eurasian-African Ottoman Empire. Russia could not compare with the great powers of that time neither in terms of economic (industrial, financial) power, nor in terms of the intensity of expansionism. The entry of the Russian Empire into the system of international relations as one of the five great powers – France, Great Britain, Austria, Prussia, and Russia – occurred during the Seven Years War of 1756-1763. Another rise to great power took place during the reign of Catherine II. The apogee of greatness and the culmination of Russia's influence on European affairs was the Congress of Vienna in 1814-1815.
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.).
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.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
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