Published May 1988 | Version v1
Journal article

Measurement and analysis of the reaction γγ → π+π-π+π-

  • 1. Technische Hochschule Aachen (Germany, F.R.). Lehrstuhl fuer Experimentalphysik 1A und 1. Physikalisches Inst.
  • 2. Bergen Univ. (Norway)
  • 3. Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany, F.R.)
  • 4. Rome Univ. (Italy)
  • 5. Institute of Nuclear Physics, Krakow (Poland)
  • 6. Glasgow Univ. (UK)
  • 7. Hamburg Univ. (Germany, F.R.). 2. Inst. fuer Experimentalphysik
  • 8. Maryland Univ., College Park (USA)
  • 9. Siegen Univ. (Gesamthochschule) (Germany, F.R.)
  • 10. Tel Aviv Univ. (Israel)
  • 11. Wuppertal Univ. (Gesamthochschule) (Germany, F.R.)

Description

We have measured the cross section of four charged pion production in photon-photon interactions in the invariant mass range 1.0 ≤ Wyy ≤ 3.2 GeV and up to Q2 = 16 GeV2. For 1.2 GeV ≤ Wyy ≤ 1.7 GeV the process is dominated by ρ0ρ0 production with a rapid rise in cross section around 1.2 GeV, well below the nominal ρ0ρ0 threshold. The observed distributions in the two particle masses and in the production and decay angles are well described by an incoherent sum of the phase-space subprocesses γγ → ρ0ρ0, → ρ0π+π-, and → π+π-π+π-. A spin-parity analysis of the ρ0ρ0 system shows Jp = 2+ to dominate, although 0+ is also possible for Wyy ≤ 1.4 GeV. Negative parity states are exluded. (orig.)

Additional details

Publishing Information

Journal Title
Z. Phys., C
Journal Volume
38
Journal Issue
4
Series
Z. Phys., C.
Journal Page Range
521-533
ISSN
0170-9739
CODEN
ZPCFD

Optional Information

Collaborations
PLUTO Collaboration.