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Anomalous low mass e/sup +/e/sup -/ pair production in 17 GeV/c. pi. /sup -/p collisions

Conference ·
OSTI ID:5159753
; ;
An experiment was performed at the Multiparticle Spectrometer using 17 GeV/c ..pi../sup -/ from the BNL AGS, triggering upon inclusive e/sup +/e/sup -/ production. Electron identification was based on two transition radiator detectors and lead-scintillator shower detectors. Good acceptance for the e/sup +/e/sup -/ pair covered the region x/sub F/ > 0.3 for all p/sub T/ and pair masses. Charged particles and photons associated with the e/sup +/e/sup -/ pair are detected over a large solid angle. e/sup +/e/sup -/ pairs of mass up to 1.2 GeV/c/sup 2/ were produced. A clear peak due to rho, ..omega.. ..-->.. e/sup +/e/sup -/ is observed. For e/sup +/e/sup -/ masses below the rho, ..omega.., an excess of events is found over those expected from known sources such as eta ..-->.. e/sup +/e/sup -/..gamma.. and ..omega.. ..-->.. e/sup +/e/sup -/..pi../sup 0/. This anomalous excess is more strongly produced at small x/sub F/. The structure of events containing anomalous e/sup +/e/sup -/ pairs is reported in an attempt to elucidate their origin. In particular, effective mass distributions of e/sup +/e/sup -/..gamma.., e/sup +/e/sup -/..pi../sup 0/, e/sup +/e/sup -/ charged hadrons are presented.
Research Organization:
Brookhaven National Lab., Upton, NY (USA); Pennsylvania Univ., Philadelphia (USA); State Univ. of New York, Stony Brook (USA)
DOE Contract Number:
AC02-76CH00016
OSTI ID:
5159753
Report Number(s):
BNL-28178; CONF-800724-23
Country of Publication:
United States
Language:
English

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Related Subjects

645101* -- High Energy Physics-- Particle Interactions & Properties-Experimental-- Electromagnetic Interactions & Properties
72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS
BOSONS
ELEMENTARY PARTICLES
ENERGY RANGE
GEV RANGE
GEV RANGE 10-100
HADRON-HADRON INTERACTIONS
INTERACTIONS
INTERMEDIATE BOSONS
INTERMEDIATE VECTOR BOSONS
MASS
MEASURING INSTRUMENTS
MESON-BARYON INTERACTIONS
MESON-NUCLEON INTERACTIONS
MULTIPARTICLE SPECTROMETERS
PAIR PRODUCTION
PARTICLE INTERACTIONS
PARTICLE PRODUCTION
PION MINUS-PROTON INTERACTIONS
PION-NUCLEON INTERACTIONS
PION-PROTON INTERACTIONS
POSTULATED PARTICLES
SPECTROMETERS