Measurement of event-by-event transverse momentum and multiplicity fluctuations using strongly intensive measuresΔ[PT,N]andΣ[PT,N]in nucleus-nucleus collisions at the CERN Super Proton Synchrotron

Results from the NA49 experiment at the CERN Super Proton Synchrotron (SPS) are presented on event-by-event transverse momentum and multiplicity fluctuations of charged particles, produced at forward rapidities in central Pb + Pb interactions at beam momenta $20A, 30A, 40A, 80A$, and $158A$ GeV/c, as well as in systems of different sizes ($p+p$, C + C, Si + Si, and Pb + Pb) at $158A$ GeV/c. This publication extends the previous NA49 measurements of the strongly intensive measure ${\mathrm{\ensuremath{\Phi}}}_{{p}_{T}}$ by a study of the recently proposed strongly intensive measures of fluctuations $\mathrm{\ensuremath{\Delta}}[{P}_{T},N]$ and $\mathrm{\ensuremath{\Sigma}}[{P}_{T},N]$. In the explored kinematic region transverse momentum and multiplicity fluctuations show no significant energy dependence in the SPS energy range. However, a remarkable system size dependence is observed for both $\mathrm{\ensuremath{\Delta}}[{P}_{T},N]$ and $\mathrm{\ensuremath{\Sigma}}[{P}_{T},N]$, with the largest values measured in peripheral Pb + Pb interactions. The results are compared with NA61/SHINE (SPS Heavy Ion and Neutrino Experiment) measurements in $p+p$ collisions, as well as with predictions of The Ultrarelativistic Quantum Molecular Dynamics and EPOS models.