The cross section of the process e + e − → π + π − has been measured in the center-of-mass energy range from 0.32 to 1.2 GeV with the CMD-3 detector at the electron-positron collider VEPP-2000. The ...measurement is based on an integrated luminosity of about 88 pb − 1 , of which 62 pb − 1 represent a complete dataset collected by CMD-3 at center-of-mass energies below 1 GeV. In the dominant region near the ρ resonance a systematic uncertainty of 0.7% was achieved. The implications of the presented results for the evaluation of the hadronic contribution to the anomalous magnetic moment of the muon are discussed. Published by the American Physical Society 2024
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CMK, CTK, FMFMET, NUK, UL
We report the status of a neural network regression model trained to extract new physics (NP) parameters in Monte Carlo (MC) simulation data. We utilize a new EvtGen NP MC generator to generate B → ...K*0µ+µ− events according to the deviation of the Wilson Coefficient C9 from its SM value, δC9. We train a three-dimensional ResNet regression model, using images built from the angular observables and the invariant mass of the di-muon system, to extract values of δC9 directly from the MC data samples. This work is intended for future analyses at the Belle II experiment but may also find applicability at other experiments.
Overview of the CMD-3 recent results Ryzhenenkov, A E; Akhmetshin, R R; Amirkhanov, A N ...
Journal of physics. Conference series,
04/2020, Volume:
1526, Issue:
1
Journal Article
Peer reviewed
Open access
The CMD-3 detector started data taking at the electron-positron collider VEPP-2000 in December 2010 with a goal to collect about 1 fb−1. The collected data sample corresponds to an integrated ...luminosity of 200 pb−1 in the center-of-mass energy range from 0.32 up to 2 GeV. This paper reports recent results on the hadronic cross sections measurements with the CMD-3 detector.
SuperKEKB, the next generation B factory, has been constructed in Japan as an upgrade of KEKB. This brand new e+ e- collider is expected to deliver a very large data set for the Belle II experiment, ...which will be 50 times larger than the previous Belle sample. Both the triggered physics event rate and the background event rate will be increased by at least 10 times than the previous ones, and will create a challenging data taking environment for the Belle II detector. The software system of the Belle II experiment is designed to execute this ambitious plan. A full detector simulation library, which is a part of the Belle II software system, is created based on Geant4 and has been tested thoroughly. Recently the library has been upgraded with Geant4 version 10.1. The library is behaving as expected and it is utilized actively in producing Monte Carlo data sets for various studies. In this paper, we will explain the structure of the simulation library and the various interfaces to other packages including geometry and beam background simulation.
The results of the experiment on the measurement of the e+e− → π+π− cross section in a cm energy range of 370–520 MeV are presented. The systematic measurement error is equal to 0.7%. In the vector ...dominance model, the pion electromagnetic radius is calculated using all the CMD-2 data on the pion form factor. The cross section for the production of a muon pair is measured in the energy range of the experiment.
Monte-Carlo generator with photon jets radiation in collinear regions for the process
e
+
e
−
→
γγ
is described in detail. Radiative corrections in the first order of
α
are treated exactly. Large ...leading logarithmic corrections coming from collinear regions are taken into account in all orders of
α
by applying the Structure Function approach. Theoretical precision of the cross section with radiative corrections is estimated to be 0.2%. This process is considered as an additional tool to measure luminosity in forthcoming experiments with the CMD-3 detector at the
e
+
e
−
collider VEPP-2000.
Existing Monte-Carlo generators with radiative corrections to the
e
+
e
-
→π
+
π
-
process are usually developed under the assumption that pions can be treated as pointlike particles. We study the
e
...+
e
-
→π
+
π
-
γ
process with final-state radiation and test this assumption using simulated events from the MCGPJ generator based on the scalar QED hypothesis. In order to increase a fraction of events with FSR, the analysis was performed in the energy region to the left from the
ρ
-meson peak (660÷785 MeV) that is based on the integrated luminosity of about 8.4 pb
-1
. The experimental data for the photon energy spectrum agree with the simulation results at 1% level.
Drift chamber for the CMD-3 detector Grancagnolo, F.; Fiore, G.; Ignatov, F.V. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
11/2010, Volume:
623, Issue:
1
Journal Article
Peer reviewed
The construction, digitizing electronics and results of test with cosmic rays of cylindrical drift chamber for CMD-3 detector are described. To uniformly fill the sensitive volume small hexagonal ...cells were chosen. The coordinate along the wire is measured by charge division technique. A resolution in the R–ϕ-plane of better than 110μm and about 3mm along the wire as well as a dE/dx resolution of about 12% were obtained in cosmic test runs.
The process e+ e−→ K+ K−π0 has been studied in the center-of-mass energy range from 1.2 to 2 GeV using a 80.6 pb−1 data sample collected with the CMD-3 detector at the electron-positron collider ...VEPP-2000. Preliminary results of the cross-section measurement are presented.
The cross section of the process e+ e−→ KS KL π0 has been studied with the CMD-3 detector at the VEPP-2000 electron-positron collider in the center-of-mass energy range from 1.1 to 2 GeV. Preliminary ...results on the total cross section of the process are presented.
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