Production of four-prong final states in photon-photon collisions

Journal Article · Fri Jan 01 04:00:00 EST 1988 · Phys. Rev. D; (United States)

DOI:https://doi.org/10.1103/PhysRevD.37.28· OSTI ID:5511838

Aihara, H; Alston-Garnjost, M; Avery, R E; Barbaro-Galtieri, A; Barker, A R; Barnes, A V; Barnett, B A; Bauer, D A; Bengtsson, H; Bintinger, D L; others, and

Results are presented on the exclusive production of four-prong final states in photon-photon collisions from the TPC/Two-Gamma detector at the SLAC e/sup +/e/sup -/ storage ring PEP. Measurement of dE/dx and momentum in the time-projection chamber (TPC) provides identification of the final states 2..pi../sup +/2..pi../sup -/, K/sup +/K/sup -/..pi../sup +/..pi../sup -/, and 2K/sup +/2K/sup -/. For two quasireal incident photons, both the 2..pi../sup +/2..pi../sup -/ and K/sup +/K/sup -/..pi../sup +/..pi../sup -/ cross sections show a steep rise from threshold to a peak value, followed by a decrease at higher mass. Cross sections for the production of the final states rho/sup 0/rho/sup 0/, rho/sup 0/..pi../sup +/..pi../sup -/, and phi..pi../sup +/..pi../sup -/ are presented, together with upper limits for phirho/sup 0/, phiphi, and K/sup *//sup 0/K-bar /sup *//sup 0/. The rho/sup 0/rho/sup 0/ contribution dominates the four-pion cross section at low masses, but falls to nearly zero above 2 GeV. Such behavior is inconsistent with expectations from vector dominance but can be accommodated by four-quark resonance models or by t-channel factorization. Angular distributions for the part of the data dominated by rho/sup 0/rho/sup 0/ final states are consistent with the production of J/sup P/ = 2/sup +/ or 0/sup +/ resonances but also with isotropic (nonresonant) production. When one of the virtual photons has mass (m/sub ..gamma..//sup 2/ = -Q/sup 2/not =0), the four-pion cross section is still dominated by rho/sup 0/rho/sup 0/ at low final-state masses W/sub ..gamma..//sub ..gamma../ and by 2..pi../sup +/2..pi../sup -/ at higher mass. Further, the dependence of the cross section on Q/sup 2/ becomes increasingly flat as W/sub ..gamma..//sub ..gamma../ increases.

• Research Organization: Lawrence Berkeley Laboratory, Berkeley, California 94720
• OSTI ID: 5511838
• Journal Information: Phys. Rev. D; (United States), Journal Name: Phys. Rev. D; (United States) Vol. 37:1; ISSN PRVDA
• Country of Publication: United States
• Language: English

Related Subjects

645101* -- High Energy Physics-- Particle Interactions & Properties-Experimental-- Electromagnetic Interactions & Properties
72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS
ANGULAR DISTRIBUTION
ANGULAR MOMENTUM
ANNIHILATION
BASIC INTERACTIONS
BOSONS
CROSS SECTIONS
DISTRIBUTION
ELECTROMAGNETIC INTERACTIONS
ELEMENTARY PARTICLES
EXCLUSIVE INTERACTIONS
GAS TRACK DETECTORS
HADRONS
INTERACTIONS
KAONS
KAONS MINUS
KAONS PLUS
MASS
MATHEMATICAL MODELS
MEASURING INSTRUMENTS
MESONS
PARITY
PARTICLE INTERACTIONS
PARTICLE MODELS
PARTICLE PRODUCTION
PARTICLE PROPERTIES
PEP STORAGE RINGS
PHOTON-PHOTON INTERACTIONS
PIONS
PIONS MINUS
PIONS PLUS
POSTULATED PARTICLES
PROJECTION SPARK CHAMBERS
PSEUDOSCALAR MESONS
QUARKS
RADIATION DETECTORS
SPARK CHAMBERS
SPIN
STORAGE RINGS
STRANGE MESONS
STRANGE PARTICLES
T CHANNEL
VECTOR DOMINANCE MODEL