Production of the F(0) Meson in Photon-photon Collisions

The CELLO collaboration Behrend, H.J. ; Fenner, H. ; Schachter, M.J. ; et al.
Z.Phys.C 23 (1984) 223, 1984.
Inspire Record 199731 DOI 10.17182/hepdata.16320

The production of thef0 in two photon collisions, with the subsequent decayf0→π+π− has been observed in the CELLO detector at PETRA. Thef0 peak was found to lie on a dipion continuum and to be shifted downwards in mass by ≃50 MeV/c2. The ππ mass spectrum from 0.8 to 1.5 GeV/c2 was well fitted by the model of Mennessier using only a unitarised Born amplitude and helicity 2f0 amplitude. The previously observed mass shift and distortion of thef0 peak are explained by strong interference between the Born andf0 amplitudes. The only free parameter in the fit of the data to the model is the radiative widthΓγγ(f0). It was found that:Γγγ(f0)=2.5±0.1±0.5 keV where the first (second) quoted errors are statistical (systematic).

2 data tables match query

Data read from graph.

Data read from graph.


Measurement of the Reaction gamma gamma ---> pi+ pi+ pi- pi- at PETRA

The CELLO collaboration Behrend, H.J. ; Fenner, H. ; Schachter, M.J. ; et al.
Z.Phys.C 21 (1984) 205, 1984.
Inspire Record 191578 DOI 10.17182/hepdata.16344

We have determined the cross section for γγ→π+π+π−π− in a way free of assumptions about the relative contributions fromρ0ρ0,ρ02π and 4π (uncorrelated phase space). We find a sharp onset above threshold and a rather high cross section of about 200 nb aroundWγγ=1.5 GeV which consists to about 40% ofρ0ρ0 production with sizeable contributions fromρ02π and 4π (PS). The total cross section as well as theρ0ρ0 content fall rather fast at higher c.m. energies. Attempts to explain this behaviour in terms of production of known resonances are not successful so far. The angular distributions do not show any significant structure pointing to resonance formation in the 4π-system. Only theρ0-meson is observed in the moment analysis. The decay distributions of theρ0 for forward produced rhos are fairly consistent with helicity conservation of the produced rhos in accordance with the VDM picture.

4 data tables match query

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RESULTS OF DECOMPOSITION OF THE CROSS SECTION INTO RHO RHO, RHO 2PI, AND 4PI(PHASE SPACE) USING TWO WIDE W BINS. SEE TEXT OF PAPER FOR DISCUSSION OF FITS.

RESULTS OF DECOMPOSITION OF THE CROSS SECTION INTO THE RHO RHO, RHO PI, AND 4PI (PHASE SPACE) USING SMALL W BINS. SEE TEXT OF PAPER FOR DISCUSSION OF FITS.

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High statistics measurement of the cross sections of gamma gamma --> pi+ pi- production.

The Belle collaboration Mori, T. ; Uehara, S. ; Watanabe, Y. ; et al.
J.Phys.Soc.Jap. 76 (2007) 074102, 2007.
Inspire Record 749358 DOI 10.17182/hepdata.51842

We report on a high statistics measurement of the total and differential cross sections of the process gamma gamma -> pi^+ pi^- in the pi^+ pi^- invariant mass range 0.8 GeV/c^2 < W < 1.5 GeV/c^2 with 85.9 fb^{-1} of data collected at sqrt{s}=10.58 GeV and 10.52 GeV with the Belle detector. A clear signal of the f_0(980) resonance is observed in addition to the f_2(1270) resonance. An improved 90% confidence level upper limit Br.(eta'(958) -> pi^+ pi^-) < 2.9 x 10^{-3} is obtained for P- and CP-violating decay of the eta'(958) meson using the most conservative assumption about the interference with the background.

1 data table match query

Total cross section.