Measurement of the W and Q/sup 2/ dependence of the total hadronic cross section in virtual photon-photon interactions

Thesis/Dissertation · Tue Jan 01 04:00:00 EST 1985

OSTI ID:5108658

Kees, K H

The total hadronic cross section for virtual photon-photon interactions, sigma/sub ..gamma.....gamma.....-->.. hadrons/, has been measured for center-of-mass energy, W, between 2 and 20 GeV. The data were collected with the TPC/Two-Gamma experiment at the PEP e/sup +/e/sup -/ storage ring at SLAC, at e/sup +/e/sup -/ center-of-mass energy of 29 GeV, and correspond to an integrated luminosity of 51.7 pb/sup -1/. A sample of 790 double-tagged events from the process e/sup +/e/sup -/ ..-->.. e/sup +/e/sup -/..gamma../sup */..gamma../sup */ ..-->.. e/sup +/e/sup -/ + hadrons was selected, in which the scattered electron and positron were detected in two high-resolution NaI calorimeters. Each virtual photon's four-momentum, q/sup 2/, and polarization mixture was determined directly from the tag electron and positron on an event-by-event basis, as was W and the photon-photon collision axis. The photon's q/sup 2/'s for this experiment were in the range -0.1 to -1.6 GeV/sup 2/, with an average q/sup 2/ of -0.3 GeV/sup 2/. The photon helicity interference terms were measured and the tau/sub TT/ term was found to be present at the two-standard-deviation level of significance. The dependence of sigma/sub ..gamma.....gamma... ..-->.. hadrons/ on q/sup 2/ is in agreement with a generalized vector-meson-dominance model, while there is very little dependence on W, and the total cross section averages 120 nb at q/sub 1//sup 2/ = q/sub 2//sup 2/ = -0.3 GeV/sup 2/.

• Research Organization: California Univ., San Diego (USA)
• OSTI ID: 5108658
• 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
ANTILEPTONS
ANTIMATTER
ANTIPARTICLES
BASIC INTERACTIONS
CROSS SECTIONS
DATA
ELECTROMAGNETIC INTERACTIONS
ELECTRON-POSITRON INTERACTIONS
ELECTRONS
ELEMENTARY PARTICLES
ENERGY DEPENDENCE
ENERGY RANGE
EXPERIMENTAL DATA
FERMIONS
FOUR MOMENTUM TRANSFER
GEV RANGE
GEV RANGE 10-100
HADRONS
INFORMATION
INTERACTIONS
LEPTON-LEPTON INTERACTIONS
LEPTONS
MOMENTUM TRANSFER
MULTIPLE PRODUCTION
NUMERICAL DATA
PARTICLE INTERACTIONS
PARTICLE PRODUCTION
PEP STORAGE RINGS
PHOTON-PHOTON INTERACTIONS
POSITRONS
STORAGE RINGS
TOTAL CROSS SECTIONS