Reaction πN → ππN near threshold
- Univ. of Virginia, Charlottesville, VA (United States)
The LAMPF E1179 experiment used the π0 spectrometer and an array of charged particle range counters to detect and record π+π0, π0p, and π+π0p coincidences following the reaction π+p → π0π+p near threshold. The total cross sections for single pion production were measured at the incident pion kinetic energies 190, 200, 220, 240, and 260 MeV. Absolute normalizations were fixed by measuring π+p elastic scattering at 260 MeV. A detailed analysis of the π0 detection efficiency was performed using cosmic ray calibrations and pion single charge exchange measurements with a 30 MeV π- beam. All published data on πN → ππN, including our results, are simultaneously fitted to yield a common chiral symmetry breaking parameter ξ =-0.25±0.10. The threshold matrix element |α0(π0π+p)| determined by linear extrapolation yields the value of the s-wave isospin-2 ππ scattering length α$$2\atop{0}$$(ππ) = -0.041±0.003 m$$-1\atop{π}$$-1, within the framework of soft-pion theory.
- Research Organization:
- Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
- Sponsoring Organization:
- USDOE; National Science Foundation (NSF)
- DOE Contract Number:
- W-7405-ENG-36
- OSTI ID:
- 10107111
- Report Number(s):
- LA-12663-T; ON: DE94003895; TRN: 94:001432
- Resource Relation:
- Other Information: DN: Thesis submitted to University of Virginia, Dept. of Physics, Charlottesville, VA; TH: Thesis (Ph.D.); PBD: Nov 1993
- Country of Publication:
- United States
- Language:
- English
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Preface and Summary
Dispersion relation for hadronic light-by-light scattering: two-pion contributions