HEPData Search

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Study of the process e+e-\to \mu+\mu- in the energy region \sqrt{s}=980, 1040 -- 1380 MeV

Achasov, M.N. ; Aulchenko, V.M. ; Beloborodov, K.I. ; et al.

Phys.Rev.D 79 (2009) 112012, 2009.

Inspire Record 798415 DOI 10.17182/hepdata.50493

The cross section of the process e+e-\to\mu+\mu- was measured in the SND experiment at the VEPP-2M e+e- collider in the energy region \sqrt{s}=980, 1040 -- 1380 MeV. The event numbers of the process e+e-\to\mu+\mu- were normalized to the integrated luminosity measured using e+e-\to e+e- and e+e-\to\gamma\gamma processes. The ratio of the measured cross section to the theoretically predicted value is 1.006\pm 0.007 \pm 0.016 and 1.005 \pm 0.007 \pm 0.018 in the first and second case respectively. Using results of the measurements, the electromagnetic running coupling constant \alpha in the energy region \sqrt{s}=1040 -- 1380 MeV was obtained <1/\alpha> = 134.1\pm 0.5 \pm 1.2 and this is in agreement with theoretical expectation.

2 data tables

Table 1

The E+ E- --> MU+ MU- cross section obtained using the (GAMMA GAMMA) luminosity measurement.

Table 2

The measured E+ E- --> E+ E- cross section in the electron angle 30 to 150 degrees.

rivet Analysis
Measurement of the e+e- -> pi+pi- cross section with the CMD-2 detector in the 370-520 MeV c.m. energy range

Aul'chenko, V.M. ; Akhmetshin, R.R. ; Banzarov, V.Sh. ; et al.

JETP Lett. 84 (2006) 413-417, 2006.

Inspire Record 728191 DOI 10.17182/hepdata.41786

The cross section of the process e+e- -> pi+pi- has been measured at the CMD-2 detector in the 370-520 MeV center-of-mass (c.m.) energy range. A systematic uncertainty of the measurement is 0.7 %. Using all CMD-2 data on the pion form factor, the pion electromagnetic radius was calculated. The cross section of muon pair production was also determined.

3 data tables

Table 1

The measured Born muon pair production cross section. Errors are statistical only.

Table 2

The measured pion form factor. The errors are statistical only.

Table 3

The measured bare PI+ PI- production cross section. This is corrected for radiative effects but excludes a correction for vacuum polarization effects. The errors are statistical only.

Search for rare Phi decays in pi+ pi_ gamma final state

The CMD-2 collaboration Akhmetshin, R.R. ; Aksenov, G.A. ; Anashkin, E.V. ; et al.

Phys.Lett.B 415 (1997) 452-462, 1997.

Inspire Record 451091 DOI 10.17182/hepdata.41643

A search for phi radiative decays has been performed using a data sample of about 2.0 million phi decays collected by the CMD-2 detector at VEPP-2M collider in Novosibirsk. From the selected e+ e- -> pi+ pi- gamma events the following results were obtained: B(phi -> f0(980) gamma) < 1x10-4 for destructive and B(phi -> f0(980) gamma) < 7x10-4 for constructive interference with the Bremsstrahlung process respectively, B(phi -> gamma -> pi+ pi- gamma) < 3x10-5 for E of gamma > 20 MeV, B(phi -> rho gamma) < 7x10-4. From the selected e+ e- -> mu+ mu- gamma events B(phi -> mu+ mu- gamma) = (2.3+-1.0)x10-5 has been obtained for E of gamma> 20 MeV. The upper limit on the P,CP-violating decay eta -> pi+ pi- has also been placed: B(eta -> pi+ pi-) < 9x10-4 . All upper limits are at 90 % C.L.

1 data table

Table 1

Only statistical errors are shown in the table.

First physical results from SND detector at VEPP-2M.

The SND collaboration Achasov, M.N. ; Beck, M.G. ; Beloborodov, K.I. ; et al.

BUDKER-INP-1997-78, 1997.

Inspire Record 450009 DOI 10.17182/hepdata.50302

The paper describes experiments with the SND detector at VEPP-2M collider, carried out during the period from October 1995 until June 1997. The total integrated luminosity of 6.4 pb^{-1} was collected in the energy range 2E=0.4-1.4 GeV (MHAD97 experiment), corresponding to 4*10^5 mu^+ mu^- pairs produced. Preliminary results of the 1996 phi-meson experiment (FI96) are presented. The total number of phi-mesons produced is 4*10^6. New data on rare decays of phi and eta (550) mesons, in particular B(phi -> eta gamma) = (1.30+-0.06+-0.07)%, B(phi -> pi^0 pi^0 gamma) = (1.1+-0.2)*10^{-4}, (M_{pi^0 pi^0} > 800 MeV), B(phi -> f^0 gamma) = (4.7+-1.0)*10^{-4}, B(phi -> eta pi^0 gamma) = (1.3+-0.5)*10^{-4}, B(phi -> eta' gamma) < 1.7*10^{-4}, B(phi -> 2 pi^0 ) < 6*10^{-4} were obtained.

4 data tables

Table 1

No description provided.

Table 2

No description provided.

Table 3

No description provided.

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rivet Analysis
Summary of experiments with the neutral detector at the e+ e- storage ring VEPP-2M

Dolinsky, S.I. ; Druzhinin, V.P. ; Dubrovin, M.S. ; et al.

Phys.Rept. 202 (1991) 99-170, 1991.

Inspire Record 321108 DOI 10.17182/hepdata.19310

The complete results of the experiments carried out with the Neutral Detector at the e + e − storage ring VEPP-2M in the energy range 2 E =0.5–1.4 GeV are reviewed. The data sample corresponds to a total integrated luminosity of 19 pb −1 .

17 data tables

Table 1

ND results from Dolinsky et al., PL B174 (1986) 453.. Statistical errors only are shown. There is an additional systematic errorof 8%.

Table 2

New ND data.. Statistical errors only are shown. There is an additional systematic errorof 8%.

Table 3

Averaged ND data.. Statistical errors only are shown. There is an additional systematic errorof 8%.

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Measurement of $\phi$ Meson Radiative Decays at the Storage Ring Vepp-2m With the Neutral Detector

Druzhinin, V.P. ; Golubev, V.B. ; Ivanchenko, V.N. ; et al.

Phys.Lett.B 144 (1984) 136-140, 1984.

Inspire Record 202874 DOI 10.17182/hepdata.6570

Results of the first experiments with the Neutral Detector at the electron-positron storage ring VEPP-2M are presented. Branching ratios of the ø-meson radiative decays have been measured: B ( ø → ηγ )=(1.30±0.06)%, B ( ø → π 0 γ )=(0.130±0.013)%, their accuracy being several times higher than the world average. The width ratio is Γ(ø→ηγ) Γ(ø→π 0 γ)=(10±1) . Using the abovementioned quantities, the ω − ø mixing angle θ v =(38.3±0.2) ° , as well as the ratio between the effective magnetic moments of the s- and u-quarks, μ s μ u =(0.57±0.03) have been calculated.

8 data tables

Table 1

CROSS SECTIONS IN THE PHI MESON PEAK (CORRECTED FOR RADIATIVE EFFECTS).

Table 2

No description provided.

Table 3

SAME AS FIG 2A, BUT KINEMATICAL RECONSTRUCTION ARE APPLIED. I.E. THE ENERGY- MOMENTUM CONSERVATIONS ARE USED TO IMPROVE THE ACCURACY OF PARTICLE ENERGIES AND ANGLES MEASURED IN DETECTOR.