On the formation by photon-photon fusion of resonances decaying to. pi. sup +. pi. sup minus. pi. sup 0 and. eta. pi. sup +. pi. sup minus

Thesis/Dissertation · Fri Jan 01 04:00:00 EST 1988

OSTI ID:7206005

Barker, A R

The TPC/Two-Gamma detector facility at PEP has been used to study the formation by {gamma}{gamma} fusion of the resonances {alpha}{sub 2}{sup 0} (1320), {eta}{prime} (958), and f{sub 1} (1285). The {alpha}{sub 2}{sup 0} (1320) was observed in reactions involving two nearly-real photons (untagged) as well as reactions involving one nearly-real and one highly virtual photon (singly-tagged). It was detected in the final state {pi}{sup +}{pi}{sup {minus}}{gamma}{gamma}, resulting from the decay {alpha}{sub 2}{sup 0} (1320) {yields} {rho}{sup {plus minus}} (770){pi}{sup {minus plus}} {yields} {pi}{sup +}{pi}{sup {minus}}{pi}{sup 0}. On the basis of the 150-event signal seen in the untagged data, the {gamma}{gamma} partial width of the {alpha}{sub 2}{sup 0} (1320) is found to be 0.82 {plus minus} 0.09 {plus minus} 0.14 keV. The {eta}{prime} (958) and f{sub 1} (1285) were also observed in the final state {pi}{sup +}{pi}{sup {minus}}{gamma}{gamma}, when the final state photons resulted from an {eta} decay. Only 3{eta}{prime} (958) events were seen in the untagged data, because of poor experimental acceptance. However, on the basis of about 36 {eta}{prime} (958) events in singly tagged {eta}{pi}{sup +}{pi}{sup {minus}} data, a measurement of the {eta}{prime}{gamma}{gamma}{sup *} form factor is reported. The observed Q{sup 2}-dependence is consistent with a {rho}-pole form. A peak at 1,273 {plus minus} 11 MeV/c{sup 2} in the {eta}{pi}{sup +}{pi}{sup {minus}} mass spectrum containing about 27 events was identified with the axial vector state f{sub 1} (1285) because it was present only in the singly-tagged data. This signature is characteristic of a spin-one state because the Yang-Landau Theorem forbids it formation in the interaction of two real photons.

• Research Organization: California Univ., Santa Barbara, CA (United States)
• OSTI ID: 7206005
• Country of Publication: United States
• Language: English

Related Subjects

662390* -- Electromagnetic Processes & Properties-- (1992-)
72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS
A2-1320 MESONS
AXIAL VECTOR MESONS
BASIC INTERACTIONS
BOSONS
DECAY
ELECTROMAGNETIC INTERACTIONS
ELECTROMAGNETIC PARTICLE DECAY
ELEMENTARY PARTICLES
ETA PRIME-958 MESONS
F1-1285 MESONS
FINAL-STATE INTERACTIONS
HADRONIC PARTICLE DECAY
HADRONS
INTERACTIONS
MASS SPECTRA
MASSLESS PARTICLES
MESONS
PARTICLE DECAY
PARTICLE INTERACTIONS
PARTICLE PRODUCTION
PARTICLE PROPERTIES
PARTICLE WIDTHS
PEP STORAGE RINGS
PHOTONS
PHOTOPRODUCTION
PSEUDOSCALAR MESONS
SPECTRA
STORAGE RINGS
TENSOR MESONS