HADES EXPERIMENT: DI-LEPTON SPECTROSCOPY IN p + p (2.2 GeV) AND C+C (1 AND 2 A GeV) COLLISIONS

摘要

The HADES (High Acceptance Di-Electron Spectrometer) is a tool designed for lepton pair (e~+e~-) spectroscopy in pion, proton and heavy ion induced reactions in the 1-2 A GeV energy range. One of the goals of the HADES experiment is to study in-medium modifications of hadron properties like effective masses, decay widths, electromagnetic form factors etc. Such effects can be probed with vector mesons (ρ, ω, φ) decaying into e~+e~- channel. The identification of vector mesons by means of a HADES spectrometer is based on invariant mass reconstruction of e~+e~- pairs. The combined information from all spectrometer sub-detectors is used to reconstruct the di-lepton signal. The recent results from 2.2 GeV p + p, 1 A GeV and 2 A GeV C+C experiments are presented.