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.
The beam energy measurement system for the VEPP-2000 electron-positron collider is described. The method of Compton backscattering of CO laser photons on the electron beam is used. The relative ...systematic uncertainty of the beam energy determination is estimated as 610 super(-5). It was obtained through comparison of the results of the beam energy measurements using the Compton backscattering and resonance depolarization methods.
Status and perspectives of the VEPP-2000 Shatunov, P. Yu; Berkaev, D. E.; Zharinov, Yu. M. ...
Physics of particles and nuclei letters,
12/2016, Letnik:
13, Številka:
7
Journal Article
Recenzirano
The electron-positron collider VEPP-2000 operates at BINP from 2010 year. The application of round colliding beams concept along with the accurate orbit and lattice correction yielded the high peak ...luminosity of 1.2 × 10
31
cm
−2
s
−1
at 500MeV. The peak luminosity limited only by beam-beam effects, while average luminosity–by present lack of positrons in whole energy range of 160–1000 MeV. To perform high luminosity at high energies the top-up injection is needed. At present new electron and positron injection complex at BINP is commissioned and ready to feed VEPP-2000 collider with intensive beams with energy of 450MeV.
The cross section for the process
e
+
e
−
→
ηK
+
K
−
wasmeasured at c.m. energies in the range between 1.56 and 2.00 GeV in an experiment with the SND detector at the VEPP-2000
e
+
e
−
collider. The ...invariant-mass distribution of kaon pairs is consistent with the hypothesis that the transition through the
ηφ
intermediate state makes a dominant contribution to the transition in question.
VEPP-2000 is the only electron–positron collider with round beams. This factor enables one to increase the beam–beam effect limit. During the 2018–2019 season, the experimental program was focused on ...the energy range of 550–990 MeV per beam. Data accumulation was performed using CMD-3 and SND detectors. The measured luminosity integral proved to have a record value of 68 pb
–1
per detector. After connecting to the BINP injection complex in 2016, the luminosity of VEPP-2000 is limited by the beam–beam effects in the entire energy range.
One of the main tasks of the NICA project is to produce colliding beams of polarized protons. It is planned to accelerate polarized protons from the source to the maximum energy in the existing ...proton synchrotron. We consider all depolarizing spin resonances in the Nuclotron and propose methods to overcome them.
Possible approaches to experimentally detecting
P
-parity violation in polarized proton or deuteron interactions with an unpolarized target are discussed. Within the first approach, a polarized ...proton or deuteron beam is scattered on a thick internal target deployed in one of rings of the NICA collider, and the spin state of the circulating beam is transformed to the mode of precession in the horizontal plane using an RF spin flipper. In this case, parity-violating effects can be probed by measuring the correlation between the interaction cross section and the particle spin direction. In an alternative experimental approach, beam-particle spins are rotated into the horizontal plane using a spin flipper, and then the beam is extracted to a beamline at a definite stage of spin precession. In this experimental scheme, which can be viewed as more traditional, one then collides the extracted beam with a dense external target and compares the measured cross sections for particles with opposite helicities passing through the target.
The VEPP-2000 electron–positron collider has been operating at the Budker Institute of Nuclear Physics (BINP) since 2010. Applying the concept of round colliding beams allowed the record value of the ...beam–beam parameter ξ ∼ 0.12 to be reached. The upgrading of the VEPP-2000 complex, including the connection to the new BINP Injection Complex and modification of the electron–position booster and the BEP–VEPP-2000 transfer channels to work at 1 GeV, resulted in a significant increase in luminosity. Work on statistical data collection using detectors is in progress.
Nuclotron based Ion Collider fAcility (NICA) project is in progress at the Joint Institute for Nuclear Research and will start experiments with heavy ions. In the context of the NICA hadronic physics ...programme double polarized
-,
- and
-collisions even at lower energies of
GeV, which will be accessible already at the initial stage of experiments,are essential tools for precise studying the spin dependence of the nucleon–nucleon strong interactions, in both elastic and deep-inelastic regimes. A special interest is interaction in few baryon systems at double strangeness, charm and beauty thresholds.For instance, polarized large-angle elastic
and
scattering near the charm threshold allows one to get an access to properties of possible exotic multiquark states and their relation to the states recently observed at LHCb.Large angle scattering of protons and deuterons on the deuteron contains unique information on the short-range structure of the deuteron, its nonnucleonic degrees of freedom and also on color transparency phenomenon. Furthermore, double polarized proton–deuteron scattering offer a possibility to test the Standard Model through the search for time-invariance (or CP-invariance under CPT symmetry) violation and parity-violation in single-polarized scattering. This paper contains suggestions for experiments with usage of the Spin Physics Detector (SPD) and discusses perspectives of the first stage of the SPD Programme. This includes experiments with nonpolarized beams too as well as collisions like
12
С–
12
С and
40
Сa–
40
Ca.
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