The NA60 experiment has studied low-mass muon pair production in
proton-nucleus (p-A) collisions with a system of Be, Cu, In, W, Pb and U
targets using a 400 GeV/c proton beam at the CERN SPS. Thanks to the
collected data sample of 180\,000 low mass muon pairs, the most precise
measurement currently available was performed for the electromagnetic
transition form factors of the η and ω mesons. The ρ line
shape was quantitatively investigated, and its effective temperature measured
for the first time in elementary collisions. The transverse momentum spectra
for the ω and ϕ mesons have been studied in the full \pt range
accessible, up to 2 GeV/c. The cross section ratios
σρ/σω and σϕ/σω have been
considered in full \pt as a function of the size of the production target.
The nuclear dependence of the production cross sections of the η, ω
and ϕ mesons has finally been studied in terms of the power law
σpA∝Aα, where the α parameter
has been found to increase as a function of \pt.Comment: On behalf of the NA60 Collaboration. arXiv admin note: substantial
text overlap with arXiv:1108.097