The strength of forward-backward multiplicity correlations have been studied in electron-positron, proton-proton and more recently in lead-lead collisions. The experimental results in proton-proton on these correlations and its comparison to different models reveals an incomplete understanding of the phenomena physical associated with these correlations. In this work, we present a study of forward backward multiplicity correlations in proton-proton collisions using PYTHIA event generator, at LHC energies. Detailed analysis is presented splitting data samples into soft and hard QCD processes, as well as, their comparisons of the correlation computed for short and long range pseudorapidity regions. Each region is analyzed taking into account effects on the colour reconnection and independently multiple parton interactions. We show that a combination of those effects are required to explain last measurements on proton-proton data, furthermore, the extraction of the strength of colour reconnection brings us also the possibility to predict the results to energies not reached in the experiment.

Theory/Pheno