a_1(1260) dominance in the process e+e- \to 4\pi at energies 1.05--1.38 GeV

The CMD-2 collaboration Akhmetshin, R.R. ; Anashkin, E.V. ; Arpagaus, M. ; et al.
Phys.Lett.B 466 (1999) 392-402, 1999.
Inspire Record 483994 DOI 10.17182/hepdata.50145

First results of the study of the process e+e- \to 4\pi by the CMD-2 collaboration at VEPP-2M are presented for the energy range 1.05--1.38 GeV. Using an integrated luminosity of 5.8 pb^{-1}, energy dependence of the processes e+e- \to \pi^+\pi^- 2\pi^0 and e+e- \to 2\pi^+ 2\pi^- has been measured. Analysis of the differential distributions demonstrates the dominance of the a_1\pi and \omega\pi intermediate states. Upper limits for the contributions of other alternative mechanisms are also placed.

3 data tables

Energy dependence of the cross section for the 2PI+ 2PI- final state. Statistical errors only.

Energy dependence of the cross section for the PI+ PI- 2PI0 final state. Statistical errors only.

Energy dependence of the cross section for the OMEGA PI0 final state. Statistical errors only.


Experiments at VEPP-2M with SND detector

The SND collaboration Achasov, M.N. ; Aulchenko, V.M. ; Baru, S.E. ; et al.
BINP-98-65, 1998.
Inspire Record 476386 DOI 10.17182/hepdata.50374

Short overview of experiments with SND detector at VEPP-2M e^+e^- collider in the energy range 2E = 400 - 1400 MeV and preliminary results of data analysis are presented.

4 data tables

No description provided.

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Measurement of the $e^+ e^- \to \pi^+ \pi^- \pi^+ \pi^-$ Cross-section in the $\rho^\prime$ (1600) Energy Region

Bacci, C. ; Baldini-Celio, R. ; Battistoni, G. ; et al.
Phys.Lett.B 95 (1980) 139-142, 1980.
Inspire Record 153382 DOI 10.17182/hepdata.27154

The cross section for the reaction e + e - →π + π - π + π - has been measured at the e + e - storage ring Adone, in the to tal c.m. energy range 1.42–2.20 GeV. The peak and the following descent of the ϱ′(1600) resonance is observed. Using also lower energy data, and assuming that only one resonant amplitude contributes to the observed cross section, the parameters of the ϱ′(1600) are deduced.

1 data table

No description provided.


Cross-section of the Reaction $e^+ e^- \to \pi^+ \pi^- \pi^+ \pi^-$ for Center-of-mass Energies From 890-{MeV} to 1100-{MeV}

Cordier, A. ; Delcourt, B. ; Eschstruth, P. ; et al.
Phys.Lett.B 81 (1979) 389-392, 1979.
Inspire Record 132828 DOI 10.17182/hepdata.27360

We present the results of a measurement of the cross section oof the reaction e + e − → π + π − π + π − from 890 to 1100 MeV in the center of mass, obtained with a magnetic detector at the Orsay Storage Ring ACO. With respect to previous experiments, the present one offers the possibility of reconstructing events with at least one constraint and his improved statistics. We find that our measurement of the cross section for e + e − → π + π − π + π − is compatible with quasi two-body production of π A 1 ( m A1 = 1.1 GeV, Γ A1 ∼ 0.2−0.3 GeV), through the ϱ and ϱ′(1600) intermediate states. We were able to states. We were able to determine the cross section of this reaction at the energy of the φ meson and consequently an upper limit on the branching ratio of φ → π + π − π + π − .

1 data table

UPPER LIMIT FOR PHI --> 4PI.


Multi-Pion Production Below 1.1-GeV by e+ e- Annihilation

Cosme, G. ; Courau, A. ; Dudelzak, B. ; et al.
Phys.Lett.B 63 (1976) 349-351, 1976.
Inspire Record 115717 DOI 10.17182/hepdata.27637

The production of multipion events by e + e − annihilation has been measured at centre of mass energies 915,990 and 1076 MeV. Both channels e + e − → π + π − π o and e + e − → π + π − π + π − have been analysed. An energy threshold effect analysed. An energy threshold effect around 919 MeV ( m ω + m π o ) has been evidenced for the π + π − π o π o channel and the cross section is consistent with the quasi two-body process e + e − → ωπ o . The cross section for π + π − π + π − is lower by an order of magnitude and increases with the energy.

2 data tables

SYSTEMATIC ERROR INCLUDED. RADIATIVE EFFECT (<15 PCT) INCLUDED.

MULTIHADRON PRODUCTION CROSS SECTION DEDUCED AS SUM OF FOUR PION CHANNELS.


Cross-Section Measurements for the Exclusive Reaction e+ e- --> 4 pi+- in the Energy Range 1.2-GeV to 3.0-GeV

Bernardini, M. ; Bollini, D. ; Brunini, P.L. ; et al.
Phys.Lett.B 53 (1974) 384-386, 1974.
Inspire Record 90250 DOI 10.17182/hepdata.27914

We have measured the crosss section for the reaction e + e − → 4 π ± in the energy range 1 2–3.0 GeV.No statistically significant evidence for a new vector meson in the ϱ″ region is found.

1 data table

No description provided.


Production of 4 pi+- and 6 pi+- by e+ e- Annihilation Between 2.4-GeV and 7.4-GeV

Jean-Marie, B. ; Abrams, G.S. ; Boyarski, A. ; et al.
SLAC-PUB-1711, 1976.
Inspire Record 108089 DOI 10.17182/hepdata.18658

None

2 data tables

No description provided.

No description provided.


Hadronic production by e+ e- collisions at the energy 990 mev with the orsay storage ring

Cosme, G. ; Jean-Marie, B. ; Jullian, S. ; et al.
Phys.Lett.B 40 (1972) 685-688, 1972.
Inspire Record 75666 DOI 10.17182/hepdata.28276

Data were taken at the energy 2 E = 990 MeV to search for multibody events, with the same large solid angle detector which has been used for the measurement of the ϱ , ω and φ production by e + e − annilations. Assuming a π + π − π 0 π 0 production by the quasi two-body process e + e − → ϱ → ωπ 0 we give the correspondi ng cross section σ (e + e − → π + π − π 0 π 0 ) = (1.1 ± 0.5) 10 −32 cm 2 . Since no events with 3 and 4 charged pions have been observed σ (e + e − → π + π − π 0 π − ) ⩽ 1.5 × 10 −33 cm 2 .

1 data table

RATIO TO MUON PAIR PRODUCTION CALCULATED FROM CROSS SECTION. INCLUDING SYSTEMATIC ERRORS.


Observation of the phi to pi+pi-pi+pi- Decay

The CMD-2 collaboration Akhmetshin, R.R. ; Anashkin, E.V. ; Arpagaus, M. ; et al.
Phys.Lett.B 491 (2000) 81-89, 2000.
Inspire Record 531667 DOI 10.17182/hepdata.41735

Using 11.6 pb^{-1} of data collected in the energy range 0.984--1.06 GeV by CMD-2 at VEPP-2M, the cross section of the reaction e+e- to pi+pi-pi+pi- has been studied. For the first time an interference pattern was observed in the energy dependence of the cross section near the phi meson. The branching ratio of the phi to pi+pi-pi+pi- decay double suppressed by the G-parity and OZI rule is measured Br(phi to pi+pi-pi+pi-) = (3.93 +- 1.74 +- 2.14) \cdot 10^{-6}. The upper limits have been placed for the decays phi to pi+pi-pi+pi-pi0 and phi to eta pi+pi- Br(phi to pi+pi-pi+pi-pi0) < 4.6 \cdot 10^{-6} 90% CL, Br(phi to eta pi+pi-) < 1.8 \cdot 10^{-5} 90% CL.

1 data table

Only statistical errors are presented. The total systematic error is estimated to about 13 PCT.


THE RESULTS OF EXPERIMENTS WITH CMD ON VEPP-2M STORAGE RING

Anikin, G.V. ; Barkov, L.M. ; Khazin, B.I. ; et al.
IYF-83-85, 1983.
Inspire Record 192095 DOI 10.17182/hepdata.37149

None

5 data tables

No description provided.

No description provided.

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