Strongly intensive variable in the model of high-energy pp interactions with the formation of string clusters

For high-energy pp scattering described in the framework of a model taking the merger of quark–gluon strings and the formation of string clusters into account, we calculate the strongly intensive variable $\Sigma$ characterizing correlations between the numbers of particles formed in two rapidity-separated observation intervals. We compare results of the calculations with experimental data of the ALICE collaboration at the Large Hadron Collider. We show that the experimentally observed increase in this variable with increasing initial energy can be explained only if the formation of string clusters consisting of the increasing number of merged strings is taken into account.