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rivet Analysis
Measurement of Resonance Productions in the Reactions $\gamma \gamma \to \pi^0 \pi^0$ and $\gamma \gamma \to \pi^0 \eta$

The JADE collaboration Oest, T. ; Olsson, J. ; Allison, J. ; et al.

Z.Phys.C 47 (1990) 343-352, 1990.

Inspire Record 295180 DOI 10.17182/hepdata.15242

Resonance production in the γγ reactionse+e−→e+e+e−π0π0 ande+e−π0η has been studied with the JADE detector at PETRA. The decay widths into γγ of thef2(1270),a0(980) anda2(1320) were measured to be$\Gamma _{\gamma \gamma } (f_2 (1270)) = 3.19 \pm 0.09_{ - 0.38}^{ + 0.22} $ Kev,Γλλ(a0(980))=0.28±0.04±0.10 KeV/BR(a0(980)→π0η) andΓλλ(a2(1320))=1.01±0.14±0.22KeV. For thef0(975) andf4(2050) upper limits of the widths were obtained,Γλλ(f0(975))<0.6 KeV, andΓλλ(f4(2050))<1.1 KeV, both at the 95% C.L. Assuming that the spin 0 background under thef2(1270) is small, thef2(1270) was found to be produced exclusively in a helicity 2 state. The helicity 0 contribution is <15% at the 95% C.L. The cross section forλλ→π0π0 in the mass range 2.0–3.5 GeV/c2 was measured for the first time. Since the cross section forλλ→π+π− is a factor ∼2 larger, ππ production in this range can be interpreted as taking place via isospin 0 production.

6 data tables

Table 1

Cross section for ABS(COS(THETA*)) < 0.3.

Table 2

Cross section under assumptions of spin 2, helicity 2 production.

Table 3

Cross section under assumption of spin 0 production.

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Comparison of the Particle Flow in $q \bar{q} \gamma$ and $q \bar{q} g$ Events From $e^+ e^-$ Annihilations at {PETRA}

The JADE collaboration Saada, F.Ould ; Allison, J. ; Ambrus, K. ; et al.

Z.Phys.C 39 (1988) 1, 1988.

Inspire Record 260834 DOI 10.17182/hepdata.15623

The particle flow distributions in the event plane of 3-jet$(e^ +e^ -\to q\bar qg)$ and of radiative 2-jet$(e^ +e^ -\to q\bar q\gamma )$ events are compared at a centre of mass energy of 35 GeV. The number of particles in the angular region opposite to the gluon in$q\bar qg$ events is found to be significantly reduced relative to the number of particles in the region opposite to the hard photon in$q\bar q\gamma $ events. This depletion is expected from the “string effect” observed in 3-jet events. It can be explained within the framework of QCD as arising from soft gluon interference.

1 data table

Table 1

Data requested from authors.

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rivet Analysis
Measurement of Resonance Productions in the Reactions $\gamma \gamma \to \pi^0 \pi^0$ and $\gamma \gamma \to \pi^0 \eta$

Comparison of the Particle Flow in $q \bar{q} \gamma$ and $q \bar{q} g$ Events From $e^+ e^-$ Annihilations at {PETRA}

Date

Collaboration Reset

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CM Energies (GeV)

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rivet Analysis Measurement of Resonance Productions in the Reactions $\gamma \gamma \to \pi^0 \pi^0$ and $\gamma \gamma \to \pi^0 \eta$

Comparison of the Particle Flow in $q \bar{q} \gamma$ and $q \bar{q} g$ Events From $e^+ e^-$ Annihilations at {PETRA}

rivet Analysis
Measurement of Resonance Productions in the Reactions $\gamma \gamma \to \pi^0 \pi^0$ and $\gamma \gamma \to \pi^0 \eta$