Multiplicity dependence of transverse-momentum spectra in hadron-hadron collisions ande+e−annihilations

We argue that the observed, but still not fully comprehended, increase of the mean transverse momentum $〈p_T〉$ with the number of charged particles $n_{\mathrm{ch}}$ in high-energy hadron-hadron collisions should be also observed in $e^{+}{e}^{-}$ annihilations into hadrons. Since no such data are available, we study the correlation of $〈p_T〉$ and $n_{\mathrm{ch}}$ using the Lund Monte Carlo model. The magnitude of the correlation increases much faster with energy for $e^{+}{e}^{-}$ annihilations than in hadronic collisions showing that these last processes cannot be treated as simple superpositions of more elementary $e^{+}{e}^{-}$ reactions.