PION PRODUCTION FROM $pi$$sup -$-p COLLISIONS IN THE LONG-RANGE INTERACTION MODEL

Journal Article · Sat Oct 15 04:00:00 EDT 1960 · Physical Review (U.S.) Superseded in part by Phys. Rev. A, Phys. Rev. B: Solid State, Phys. Rev. C, and Phys. Rev. D

DOI:https://doi.org/10.1103/PhysRev.120.599· OSTI ID:4144364

Salzman, F; Salzman, G

Long-range interactions of negative pions with protons resulting in single and double pion production are examined in terms of a meson field theory model in which it is assumed that there is a pion-pion interaction and that the single virtual pion exchange graphs are dominant in largeimpact-parameter collisions. This pion exchange leads, in single pion production, to an "excited state," pi *, which "decays" into two pions, and, in double pion production, also to an "excited state." N*, which "decays" into a pion and a nucleon. For sufficiently high relative energy of the incident pi /sup -/ and proton, each of these processes can occur for small values of the invariant square of the virtual pion four-momentum, ?2, in which case the virtual pion carries very little transverse three-momentum. For small ?2 it is shown that it is reasonable to neglect final state interactions between the "decay products" of the pi * and those of the N*. It is found that in the limit?2 - - mu /sup 2/, where mu is the pion rest mass, the virtual pion behaves kinematically, in the pi * barycentric system. as an incoming pion which scatters elastically with the incident pi /sup -/, and also behaves, in the N* barycentric system, as an incoming pion which scatters elastically with the incident proton. Thus, for small ?2 in the physical region the pi * and N* vertices are defined as the corresponding off-the-mass-shell scattering amplitudes. A ratio of appropriately defined double-tosingle pion production cross sections is obtained which is independent of the details of the assumed pion-pion interaction. and depends only on the relative strengths of N* and N formation. This ratio is estimated by means of the p-wave static nucleon model, applied in appropriate coordinate systems. For incident 5-bev/c pions this model leads to double pion production which is important compared to single pion production, both because of the 3/2 3/ 2 pionnucleon resonance and because of important phase-space factors. Kinematical considerations similar to those described above suggest that this model may also be the theoretical genesis of the "two fireballs" model proposed for ultrarclativistic nucleon-nucleon collisions. (auth)

• Research Organization: European Organization for Nuclear Research, Geneva; Univ. of Colorado, Boulder
• NSA Number: NSA-15-003350
• OSTI ID: 4144364
• Journal Information: Physical Review (U.S.) Superseded in part by Phys. Rev. A, Phys. Rev. B: Solid State, Phys. Rev. C, and Phys. Rev. D, Journal Name: Physical Review (U.S.) Superseded in part by Phys. Rev. A, Phys. Rev. B: Solid State, Phys. Rev. C, and Phys. Rev. D Vol. Vol: 120; ISSN PHRVA
• Country of Publication: Country unknown/Code not available
• Language: English

Related Subjects

COLLISIONS
DECAY
ENERGY
FIELD THEORY
INTERACTIONS
PHYSICS
PI MESONS
PIONS
PRODUCTION
RESONANCE