It is argued that a standard measurement of multiplicities in proton-proton collisions is sufficient to construct a single nucleon fragmentation function. A proposed method is based on measurement of mean values of produced particles and pairs of particles in symmetric and asymmetric rapidity bins.

The ratios of particle densities in lead-lead and proton-lead collisions to particle density in proton-proton collision in the central rapidity region at the LHC energy are predicted on the basis of wounded quark-diquark model.

Using the Landshoff-Nachtmann two-gluon exchange model of the pomeron, the double pomeron exchange contribution to production of gluon pairs in the central region of rapidity is calculated. The results are compared with those for production of quark-antiquark pairs.

Small momentum transfer elastic pion-proton cross-section at high energies is calculated assuming the proton is composed of two constituents, a quark and a diquark. We find that it is possible to fit very precisely the data when (i) the pion acts as a single entity (no constituent quark structure) and (U) the diquark is rather large, comparable to the size of the proton.

The wounded quark-diquark model predictions for charged pions multiplicities in PbPb and pPb collisions in the central rapidity region at √s = 17.3 GeV c.m. energy are presented.

We investigate the wounded nucleon model contribution to the forward-backward multiplicity correlation coefficient measured by the STAR Collaboration in AuAu collisions at √s = 200 GeV.

The forward-backward long-range multiplicity correlations in proton-proton collisions are investigated in the model with two independent sources of particles: one left- and one right-moving wounded nucleon. A good agreement with the UA5 Collaboration proton-antiproton data at the c.m. energy of 200 GeV is observed. For comparison the model with only one source of particles is also discussed.

Small momentum transfer elastic proton-proton cross-section at high energies is calculated assuming the nucleon composed of two constituents - a quark and a diquark. A comparison to data (described very well up to -t ≈ 2 GeV2/c) allows to determine some properties of the constituents. While quark turns out fairly small, the diquark appears to be rather large, comparable to the size of the proton.

This contribution reports on the results obtained in the two recently published papers [A. Bialas, A. Bzdak, K. Zalewski, Phys. Lett. B710, 332 (2012); A. Bialas, K. Zalewski, Acta Phys. Pol. B 43, 1357 (2012)] demonstrating that data of the STAR Collaboration show a substantial asymmetric component in the rapidity distribution of the system created in central Au-Au collisions, implying that boost invariance is violated on the event-by-event basis even at the mid c.m. rapidity.

In this contribution, we will discuss how the study of various fluctuation observables may be used to explore the phase diagram of the strong interaction. We will briefly summarize the present study of experimental and theoretical research in this area. We will then discuss various corrections and issues which need to be understood and applied for a meaningful comparison of experimental measurements with theoretical predictions.