# pi^0 -> gamma gamma*, omega -> pi^0 gamma*, and rho -> pi gamma* decays
in nuclear medium

Research paper by **Agnieszka Bieniek, Anna Baran, Wojciech Broniowski**

Indexed on: **22 Jun '01**Published on: **22 Jun '01**Published in: **Nuclear Theory**

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#### Abstract

We calculate the medium modification of the pi-omega-rho vertex and analyze
its significance for the pi^0 -> gamma gamma*, omega -> pi^0 gamma*, and rho ->
pi gamma* decays in nuclear matter. We use a relativistic hadronic approach at
zero temperature and in the leading-density limit, and consider decays of
particles at rest with respect to the medium. It is shown that for the pi^0 ->
gamma gamma* the effects of the Delta isobar cancel almost exactly the effects
of the nucleon ph excitations, such that the net medium effect is small. On the
contrary, for the decays omega -> pi^0 gamma* and rho -> pi gamma* we find a
sizeable increase of the partial widths at virtualities of the photon in the
range 0.3-0.6 GeV. The effect has direct significance for the calculation of
dilepton yields from the Dalitz decays in relativistic heavy-ion collisions.