Narrow Results

In this work we present some results of the interaction of high-energy muons with emulsion nuclei. The interaction results in emission of a number of fragments as a consequence of electromagnetic dissociation of the excited target nuclei. This excitation is attributed to absorption of photons by the target nuclei due to the intense electric field of the very fast incident muon particles. The interactions take place at impact parameters that allow ultra-peripheral collisions to take place, leading to giant resonances and hence multifragmentation of emulsion targets. Charge identification, range, energy spectra, angular distribution and topological cross-section of the produced fragments are measured and evaluated.

The exclusive photoproduction of the heavy vector mesons $\mathrm{\Psi }(1S,2S)$ is investigated in the context of ultra-peripheral collisions proton-proton and nucleus-nucleus for the energies available at the LHC run 2. Using the light-cone color dipole formalism, it was calculated the transverse momentum distribution in the central rapidity region, in which it is expected major contribution for the process.

Ultra-peripheral heavy ion collisions involve long range electromagnetic interactions at impact parameters larger than twice the nuclear radius, where the strong nucleon-nuecleon interactions are uneffective. We present recent results from the STAR collaboration on these ultra-peripheral interactions likes incoherent ρ⁰ production in deuteron-gold collisions and interferometry in gold-gold collisions.

By using a Regge-pole model for vector meson production (VMP), that successfully describes the HERA data, we analyse the correlation between VMP cross sections in photon-induced reactions at HERA and those in ultra-peripheral collisions at the Large Hadron Collider (LHC). The role of the low-energy behaviour of VMP cross sections in γp collisions is scrutinized.