$\rho /\omega$ properties from dilepton spectra in $pA$ reactions at 12 GeV

Abstract

The dilepton production from $pC$ and $pCu$ collisions at $T_{lab}=12$ GeV is calculated using the semi-classical BUU transport model, that includes the off-shell propagation of vector mesons nonperturbatively and calculates the width of the vector mesons dynamically. It is found that the collisional broadening of the vector meson width and dropping vector meson masses lead to a small enhancement of the dilepton yield below the $\omega$ meson mass pole in $pCu$ collisions compared to $pC$, which is, however, not sufficient to explain the enhanced production of dileptons as observed in the experiment by the KEK-PS E325 collaboration. It is argued that such in-medium effects are expected to be small due to kinematical reasons -- the dominant part of vector mesons radiate dileptons and decay outside the nucleus due to the finite formation time for $\rho$ and $\omega$ mesons, which is large by Lorentz covariance since the produced vector mesons move with high velocity relative to the target nucleus.

14 pages, including 5 eps figures, to be published in Phys. Lett. B

References in corpus (7)

• Relativistic Hadron-Hadron Collisions in the Ultra-Relativistic Quantum Molecular Dynamics Model (UrQMD)
• Excitation functions of hadronic observables from SIS to RHIC energies
• Observation of $\rho /\omega$ Meson Modification in Nuclear Matter
• Semiclassical transport of hadrons with dynamical spectral functions in A+A collisions at SIS/AGS energies
• Perspectives of $e^{+}{e}^{-}$ production in pp, pd and p Be reactions at SIS energies
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Cited by in corpus (8)

• Dilepton production and off-shell transport dynamics at SIS energies
• Dilepton production in heavy ion collisions at intermediate energies
• Dilepton production in heavy-ion collisions with in-medium spectral functions of vector mesons
• In-medium Properties of Hadrons -- Observables
• In-Medium Properties of Hadrons - Observables II
• Dilepton production in elementary and in heavy ion reactions
• Hadrons in Medium
• Dilepton production at SIS energies