A
bstract
The cross section of the process
e
+
e
−
→
π
+
π
−
has been measured in the Spherical Neutral Detector (SND) experiment at the VEPP-2000
e
+
e
−
collider VEPP-2000 in the energy region 525
...<
s
<
883 MeV. The measurement is based on data with an integrated luminosity of about 4.6 pb
−
1
. The systematic uncertainty of the cross section determination is 0.8% at
s
>
0
.
600 GeV. The
ρ
meson parameters are obtained as
m
ρ
= 775
.
3 ± 0
.
5 ± 0
.
6 MeV, Γ
ρ
= 145
.
6 ± 0
.
6 ± 0
.
8 MeV,
B
ρ
→
e
+
e−
×
B
ρ
→
π
+
π−
= (4
.
89 ± 0
.
02 ± 0
.
04) × 10
−
5
, and the parameters of the
e
+
e
−
→
ω
→
π
+
π
−
process, suppressed by
G
-parity, as
B
ω
→
e
+
e−
×
B
ω
→
π
+
π−
= (1
.
32 ± 0
.
06 ± 0
.
02) × 10
−
6
and and
ϕ
ρω
= 110
.
7 ± 1
.
5 ± 1
.
0 degrees.
In this paper, we describe the project of a photon source with energies up to 2500 MeV at the SKIF synchrotron radiation facility (under construction in Novosibirsk). It is intended for experiments ...on photonuclear reactions, nonlinear QED, EM detector calibration and other applications. A polarized photon beam with a flux of 10
6
–10
8
Hz (in full spectrum) is produced using Compton backscattering (or inverse scattering) of IR, visible, and UV laser radiation, as well as the UV band of its own synchrotron radiation, on the SKIF electron beam (15 kHz). Spectrum monochromatization with collimators or/and tagging system by recoil electrons is possible. The discrepancy between experimental and theoretical photofission cross sections of actinide nuclei in a photon energy range of hundreds of MeV has been known since the 1980s, so it is proposed to study these cross sections in the first series of experiments.
The Laser Polarimeter is being developed at VEPP-4M collider for beam energy calibration by Resonant Depolarization technique. The essential part of this facility is a photon-tracking detector ...measuring coordinates of backscattered gammas.
Results are presented from measuring the
cross section and effective neutron timelike form factor. Data are collected in 2020–2021 at the VEPP-2000
collider in the 1891 to 2007 MeV center-of-mass ...range of energies. The general purpose nonmagnetic SND detector is used to detect neutron–antineutron events. The time-of-flight approach is used to select
events. The measured cross section is 0.4–0.6 nbn. The neutron form factor in the investigated range of energies varies from 0.3 to 0.2.
Study of the Process in the Energy Range GeV Achasov, M. N.; Barnyakov, A. Yu; Beloborodov, K. I. ...
Physics of atomic nuclei,
2023/12, Letnik:
86, Številka:
6
Journal Article
Recenzirano
The
cross section is measured in the center-of-mass energy range from 1.07 to 2.00 GeV in the decay channel
,
. The data set with an integrated luminosity of 242 pb
accumulated in the experiment with ...the SND detector at the VEPP-2000
collider is analyzed.
The Spherical Neutral Detector (SND) is an experiment for e+e− annihilation study at low energies 0.2−2 GeV. The light quark anti−quark bound states are the main subject of study at these energies. ...They express themselves as resonances in the e+e− hadronic cross sections. Hadronic cross sections could be recalculated to hadronic vacuum polarization (HVP). The Standard Model predictions today are limited by HVP which is not calculable with modern QCD theory. In this talk we present the review of the hadronic cross sections measurements at SND and new measurements: e+e− → π+π−, π0γ, π+π−π0, ωπ0, K+K−η, η, KsKLπ0, π+π−π0η, ωπ0η e.t.c.
The process
was studied in the energy range between 1 and 2 GeV to the best precision in the world. The data used correspond to an integrated luminosity of
accumulated with the SND detector at the ...VEPP-2000
collider. The statistical accuracy of the measured cross section is 2 to 22
, whereas the systematic uncertainty is 2.6 to 14
. The present results agree with the results of earlier measurements but have a better precision.
The process
is studied in the range of center-of-mass (c.m.) collision energies between 1.05 and 2.00 GeV on the basis of data corresponding to an integrated luminosity of 94.5 pb
that were ...accumulated in an experiment with the SND detector at the VEPP-2000
collider. The cross section for this process was measured for the first time and was found to receive a dominant contribution from the mechanism of a transition through an
intermediate state. The cross section measured for the process
agrees with the results of earlier measurements in the channel
. At a level of 5.7 standard deviations (5.7
), it is established that the process
is not fully described by hadronic intermediate states of the
type. The cross section was measured for this missing contribution, which may be generated by radiative processes—for example,
. It ranges from 15 to 20 pb over a broad energy interval extending from 1.3 to 1.9 GeV.
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