Date

Measurement of e+e- -> pi+pi- cross section with CMD-2 around rho-meson

The CMD-2 collaboration Akhmetshin, R.R. ; Anashkin, E.V. ; Arbuzov, A.B. ; et al.
Phys.Lett.B 527 (2002) 161-172, 2002.
Inspire Record 568807 DOI 10.17182/hepdata.27037

The cross section of the process e+e- -> pi+pi- has been measured using about 114000 events collected by the CMD-2 detector at the VEPP-2M e+e- collider in the center-of-mass energy range from 0.61 to 0.96 GeV. Results of the pion form factor determination with a 0.6% systematic uncertainty are presented. Implications for the hadronic contribution to the muon anomalous magnetic moment are discussed.

1 data table match query

Updated measured values of the pion form factor and 'bare' cross section.


Measurement of omega meson parameters in pi^+pi^-pi^0 decay mode with CMD-2

The CMD-2 collaboration Akhmetshin, R.R. ; Anashkiny, E.V. ; Aulchenko, V.M. ; et al.
Phys.Lett.B 476 (2000) 33-39, 2000.
Inspire Record 523691 DOI 10.17182/hepdata.27036

About 11 200 e^+e^- -> omega -> pi^+pi^-pi^0 events selected in the center of mass energy range from 760 to 810 MeV were used for the measurement of the \omega meson parameters. The following results have been obtained: sigma _{0}=(1457 \pm 23 \pm 19)nb, m_{\omega}=(782.71 \pm 0.07 \pm 0.04) MeV/c^{2}, \Gamma_{\omega}=(8.68 \pm 0.23 \pm 0.10) MeV, \Gamma_{e^+e^-}\cdot Br (\omega -> pi^+pi^-pi^0)= (0.528 \pm 0.012 \pm 0.007) \cdot 10^{-3} MeV.

1 data table match query

Updated measurements of the E+ E- --> OMEGA --> PI+ PI- PI0 measured and 'bare' cross sections.


Measurement of phi meson parameters with CMD-2 detector at VEPP-2M collider

Akhmetshin, R.R. ; Aksenov, G.A. ; Anashkin, E.V. ; et al.
Phys.Lett.B 364 (1995) 199-206, 1995.
Inspire Record 406880 DOI 10.17182/hepdata.28437

Results of the measurement of the φ meson parameters with the general purpose detector CMD-2 at the upgraded e + e − collider VEPP-2M at Novosibirsk are presented. This is the first measurement of the four major φ decay modes in a single e + e − experiment. The results based on about 55,600 identified hadronic events are consistent with previous measurements, and have precision comparable to the current world average.

1 data table match query

No description provided.


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 match query

Only statistical errors are shown in the table.


Measurement of the $\phi$ meson parameters with CMD-2 detector at VEPP-2M Collider

The CMD-2 collaboration Akhmetshin, R.R. ; Anashkin, E.V. ; Arpagaus, M. ; et al.
Phys.Lett.B 466 (1999) 385, 1999.
Inspire Record 502164 DOI 10.17182/hepdata.41645

About 300 000 $e^+e^-\to \phi\to K^0_L K^0_S$ events in the center of mass energy range from 984 to 1040 MeV were used for the measurement of the $\phi$ meson parameters. The following results have been obtained: $\sigma_0 = (1367 \pm 15 \pm 21) nb, m_{\phi}=(1019.504 \pm 0.011 \pm 0.033) MeV/c^2, \Gamma_\phi=(4.477 \pm 0.036 \pm 0.022) MeV, \Gamma_{e^+e^-}\cdot B(\phi\to K^0_L K^0_S) = (4.364 \pm 0.048 \pm 0.065)\cdot 10^{-4}$ MeV.

4 data tables match query

Updated measurements of the E+ E- --> PHI --> K0L K0S measured and 'bare' cross sections for SCAN 1.

Updated measurements of the E+ E- --> PHI --> K0L K0S measured and 'bare' cross sections for SCAN 2.

Updated measurements of the E+ E- --> PHI --> K0L K0S measured and 'bare' cross sections for SCAN 3.

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Precise measurement of the positive muon anomalous magnetic moment.

The Muon g-2 collaboration Brown, H.N. ; Bunce, G. ; Carey, R.M. ; et al.
Phys.Rev.Lett. 86 (2001) 2227-2231, 2001.
Inspire Record 552899 DOI 10.17182/hepdata.41719

A precise measurement of the anomalous g value, a_mu=(g-2)/2, for the positive muon has been made at the Brookhaven Alternating Gradient Synchrotron. The result a_mu^+=11 659 202(14)(6) X 10^{-10} (1.3 ppm) is in good agreement with previous measurements and has an error one third that of the combined previous data. The current theoretical value from the standard model is a_mu(SM)=11 659 159.6(6.7) X 10^{-10} (0.57 ppm) and a_mu(exp)-a_mu(SM)=43(16) X 10^{-10} in which a_mu(exp) is the world average experimental value.

1 data table match query

The anomalous G value is related to the gyromagnetic ratio by MOM(N=A_MU) =(G-2)/2.


Improved measurement of the positive muon anomalous magnetic moment.

The Muon (g-2) collaboration Brown, H.N. ; Bunce, G. ; Carey, R.M. ; et al.
Phys.Rev.D 62 (2000) 091101, 2000.
Inspire Record 533384 DOI 10.17182/hepdata.41731

A new measurement of the positive muon's anomalous magnetic moment has been made at the Brookhaven Alternating Gradient Synchrotron using the direct injection of polarized muons into the superferric storage ring. The angular frequency difference omega_{a} between the angular spin precession frequency omega_{s} and the angular orbital frequency omega_{c} is measured as well as the free proton NMR frequency omega_{p}. These determine R = omega_{a} / omega_{p} = 3.707~201(19) times 10^{-3}. With mu_{mu} / mu_{p} = 3.183~345~39(10) this gives a_{mu^+} = 11~659~191(59) times 10^{-10} (pm 5 ppm), in good agreement with the previous CERN and BNL measurements for mu^+ and mu^-, and with the standard model prediction.

1 data table match query

The anomalous g value is related to the gyromagnetic ratio by MOM(NAME=ANOMALOUS MAGNETIC) = (G-2)/2. The beam momentum spread is about 1 PCT.


High-statistics measurement of the pion form factor in the rho-meson energy range with the CMD-2 detector

The CMD-2 collaboration Akhmetshin, R.R. ; Aulchenko, V.M. ; Banzarov, V.Sh. ; et al.
Phys.Lett.B 648 (2007) 28-38, 2007.
Inspire Record 728302 DOI 10.17182/hepdata.41782

We present a measurement of the pion form factor based on e+e- annihilation data from the CMD-2 detector in the energy range 0.6&lt;sqrt(s)&lt;1.0 GeV with a systematic uncertainty of 0.8%. A data sample is five times larger than that used in our previous measurement.

2 data tables match query

Measured values of the pion form factor. The errors are statistical only.

Measured value of the bare PI+ PI- cross section including corrections for radiative effects but excluding corrections for vacuum polarization effects. The errors are statistical only.


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 match query

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

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

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.


MEASUREMENT OF THE PION FORM-FACTOR NEAR THE THRESHOLD OF THE REACTION e+ e- ---> pi+ pi- WITH A TIME-OF-FLIGHT DETECTOR

Vasserman, I.B. ; Ivanov, P.M. ; Kezerashvili, G.Ya. ; et al.
SLAC-TRANS-0196, 1981.
Inspire Record 164524 DOI 10.17182/hepdata.37120

None

1 data table match query

RADIATIVE CORRECTIONS APPLIED.