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THE PION-PION CROSS SECTION BY THE CHEW-LOW METHOD (thesis)

Technical Report ·
DOI:https://doi.org/10.2172/4819836· OSTI ID:4819836
By the use of the Alvarez 72-inch hydrogen bubble chamber exposed to a 1.25-Bev/c pi plus or minus beam designed by Professor Frank Crawford, a study of the processes pi /sup +/ + p yielding p + pi/sup +/ and pi/sup -/ + p yielding p + pi/sup -/ + pi/sup 0/ was carried out. All together, 1737 pi /sup +/ and 466 pi /sup -/ events with low momentum transfer to the proton (less than 400 Mev/c) were measured. Evidence was found for a T = J = l di-pion resonance of mass 730 Mev and full width at half maximum of 150 Mev (total di-pion energy squared = 29 neutral pion masses squared). The height of the cross section by extrapolation for both the pi /sup +/ and pi /sup -/ data and in the physical region for the pi /sup +/ is consistent with (2J + l) 4 pi lambda /sup 2/ for a p-wave resonance. Angular distributions were determined in the physical region for the pi /sup +/ data. These distributions are strongly dominated by a cos/ sup 2/ theta /sub pi pi / term (s-,d-, and f-wave resonances can be ruled out by this experiment). The pi /sip -/ data do not show the dominance of the single-pion exchange process in the physical region. The cross section sigma / sub pi/-/sub pi/0 as determined by the ChewLow extrapolation method does show a resonant rise, thus indicating that the applicability of the Chew-Low method is not restricted to situations in which the physical region contains already as much information as one hopes to learn by extrapolation. (auth)
Research Organization:
University of California, Lawrence Radiation Laboratory, Berkeley, CA (US)
Sponsoring Organization:
US Atomic Energy Commission (AEC)
DOE Contract Number:
W-7405-ENG-48
NSA Number:
NSA-16-006924
OSTI ID:
4819836
Report Number(s):
UCRL-9886
Country of Publication:
United States
Language:
English