Probing meson spectral functions with double differential dilepton spectra in heavy-ion collisions

Abstract:The double differential dilepton spectrum d/(d2d⊥2) at fixed transverse mass M⊥ allows a direct access to the vector meson spectral functions. Within a fireball model the sensitivity of d/(d2d⊥2) against variations of both the in-medium properties of mesons and the dynamics of the fireball is investigated. In contrast to the integrated invariant-mass spectrum d/d2, in the spectrum d/(d2d⊥2) with fixed M⊥ the ω signal is clearly seen as bump riding on the ρ background even in case of strong in-medium modifications.[3mm]