Eur. Phys. J. A (2007) 31: 245-254
https://doi.org/10.1140/epja/i2006-10169-6

Regular Article - Hadron Physics

Inclusive ω photoproduction from nuclei and ω in the nuclear medium

¹ Departamento de Fısica Teórica and IFIC, Centro Mixto Universidad de Valencia-CSIC, Institutos de Investigación de Paterna, Aptd. 22085, 46071, Valencia, Spain
² Grupo de Fısica Nuclear, Departamento de Fisica Fundamental e IUFFyM, Facultad de Ciencias, Universidad de Salamanca, Plaza de la Merced s/n, E-37008, Salamanca, Spain

^* e-mail: Murat.Kaskulov@theo.physik.uni-giessen.de

Received: 28 October 2006
Accepted: 22 December 2006
Published online: 1 February 2007

Abstract

With the aim of extracting information on the shift of the ω mass in the nuclear medium we analyze data obtained at ELSA from where claims for evidence of a mass shift of the ω have been made. We develop a Monte Carlo simulation code which takes into account the possible reactions in the experimental set-up of (γA → π⁰γX) in the vicinity of the ω production region with subsequent ω → π⁰γ decay. We compare our results with experiment for the distribution of π⁰γ invariant masses and conclude that the distribution is compatible with an enlarged ω width of about 90MeV at nuclear-matter density and no shift in the mass. This change in the width would be compatible with the preliminary results obtained from the transparency ratio in the A-dependence of ω production. The discrepancy of the present conclusions with former claims of an evidence for a shift of the ω mass stems from a different choice of background which is discussed in the paper.