Speaker
Christoph Mayer
(Polish Academy of Sciences (PL))
Description
The strong electromagnetic fields generated in the collision of Pb ions at the LHC allow photon-photon and photonuclear interactions to be studied in a kinematic regime unexplored so far. The exclusive photoproduction of vector mesons was studied with the ALICE detector in ultra-peripheral PbPb collisions, where the impact parameter is larger than the sum of the nuclear radii and hadronic interactions are strongly suppressed.
A data sample corresponding to about 3.6 microb^-1 was collected during the 2010 LHC heavy-ion run at an energy sqrt(s_NN) = 2.76 TeV using triggers that select ultra-peripheral collisions.
In this data sample, Rho0 photoproduction at mid-rapidity corresponds to a photon-nucleon center of mass energy of 45 GeV, about 4 times higher than in previous experiments. The cross section for exclusive rho0 production was measured, and the relative contributions to the invariant mass distribution from resonant and non-resonant processes was evaluated.
The results are compared to calculations with different theoretical models.
Primary author
Collaboration ALICE
(CERN, Geneva, Switzerland)
Co-author
Christoph Mayer
(Polish Academy of Sciences (PL))
