Dielectron Production in {sup 12}C+{sup 12}C Collisions at 2A GeV with the HADES Spectrometer

Journal Article · Fri Feb 02 00:00:00 EST 2007 · Physical Review Letters

DOI:https://doi.org/10.1103/PHYSREVLETT.98.052302· OSTI ID:20955421

Agakichiev, G; Gilardi, C; Kuehn, W; Lehnert, J; Lins, E; Metag, V; Pechenov, V; Perez, T; Ritman, J; Spruck, B; Toia, A ^[1]; Agodi, C; Bellia, G; Coniglione, R; Cosentino, L; Finocchiaro, P; Maiolino, C; Piattelli, P; Sapienza, P; Vassiliev, D ^[2]

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1. II.Physikalisches Institut, Justus Liebig Universitaet Giessen, 35392 Giessen (Germany)
2. Istituto Nazionale di Fisica Nucleare, Laboratori Nazionali del Sud, 95125 Catania (Italy)

The invariant-mass spectrum of e{sup +}e{sup -} pairs produced in {sup 12}C+{sup 12}C collisions at an incident energy of 2 GeV per nucleon has been measured for the first time. The measured pair production probabilities span over 5 orders of magnitude from the {pi}{sup 0}-Dalitz to the {rho}/{omega} invariant-mass region. Dalitz decays of {pi}{sup 0} and {eta} account for all the yield up to 0.15 GeV/c{sup 2}, but for only about 50% above this mass. A comparison with model calculations shows that the excess pair yield is likely due to baryon-resonance and vector-meson decays. Transport calculations based on vacuum spectral functions fail, however, to describe the entire mass region.

• OSTI ID: 20955421
• Journal Information: Physical Review Letters, Vol. 98, Issue 5; Other Information: DOI: 10.1103/PhysRevLett.98.052302; (c) 2007 The American Physical Society; Country of input: International Atomic Energy Agency (IAEA); ISSN 0031-9007
• Country of Publication: United States
• Language: English

Related Subjects

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS
CARBON 12 BEAMS
CARBON 12 REACTIONS
CARBON 12 TARGET
COLLIDING BEAMS
ELECTRON-POSITRON INTERACTIONS
ELECTRONS
ETA MESONS
MASS SPECTRA
PAIR PRODUCTION
PARTICLE DECAY
PIONS NEUTRAL
POSITRONS
PROBABILITY
RESONANCE PARTICLES
SPECTRAL FUNCTIONS
SPECTROMETERS
VECTOR MESONS