We report results on ρ(770)0 → π+ π- production at midrapidity in p + p and peripheral Au + Au collisions at psNN = 200 GeV. This is the first direct measurement of ρ(770)0 → π+ π- in heavy-ion collisions. The measured ρ0 peak in the invariant mass distribution is shifted by ∼40 MeV=c2 in minimum bias p + p interactions and ∼70 MeV=c2 in peripheral Au + Au collisions. The ρ0 mass shift is dependent on transverse momentum and multiplicity. The modification of the ρ0 meson mass, width, and shape due to phase space and dynamical effects are discussed.
All Science Journal Classification (ASJC) codes
- Physics and Astronomy(all)