Speaker
Description
We shall present theoretical predictions for production of
$J/\Psi$ meson, $\gamma\gamma$, one and two pairs of leptons
and $p \bar{p}$ in ultrarelativistic UPC.
Analyses are done in the impact parameter space equivalent photon approximation.
We use so-called realistic form factor which is a Fourier transform
of the charge distribution in nuclei.
We consider both ultraperipheral and for the first time semi-central collisions.
We get very good description of the latest ALICE data for single $J/\psi$
photoproduction for different centrality bins. We show that a correct interpretation
of data requires to use a modification of a photon flux.
Next, we will report on our results for light-by-light scattering.
Our rather optimistic predictions became a motivation for experimental groups
to perform corresponding experimental studies.
Our calculations were a source of a ATLAS Monte Carlo simulation.
A recent ATLAS measurement is a first experimental observation
of the PbPb$\to$PbPb$\gamma\gamma$ mechanism and $\gamma \gamma \to \gamma \gamma$ scattering.
Next we will discuss a electromagnetic double scattering
production of two positron-electron pairs.
Our calculations suggest that measurements (with the help of
detectors at the LHC) are possible in a near future. We get very good agreement with ALICE data
for single $e^+e^-$ pair production.
Finally we shall present very fresh results for $p \bar{p}$ production.
We are a first group which can describe, concurrently, angular distributions and total cross section
for $\gamma\gamma \to p \bar{p}$ process. We inserted this elementary cross section
into nuclear UPC calculations and, dependently on $z=\cos\theta$ limitation,
we get a cross section of the order of 1 mb.