Evidence of forward–backward correlation of pions in ultra-relativistic ring- and jet-like events in 16O- Ag/ Br interactions at Elab= 60 A GeV

An investigation on the presence of the forward–backward correlations in the pions multiplicity, emitted in 16O- Ag/ Br interactions at energy Elab= 60 A GeV are carried out. The study of the forward–backward correlation between various observables which is separated by two different pseudorapidity intervals can be treated as an important probe to defining the primordial conditions for the formation of the Quark Gluon Plasma (QGP). We have observed the dependency of correlation fluctuations and correlation strength on pseudorapidity (η) and the increasing width of the pseudorapidity bin size Δη. The roughness of the multiplicities and the particle number deviations are also investigated. The nuclear photographic emulsion technique has been employed to collect the experimental data. We have performed the FRITIOF and Ultra-relativistic Quantum Molecular Dynamics (UrQMD) simulations to compare the experimental results with the simulated results. The analysis strongly indicates the presence of forward–backward correlations in the experimental distributions of pions beyond statistical noise. We have also analyzed the ring- and jet-like structure to confirm the presence of the forward–backward correlations in the multiplicities of 16O- Ag/ Br interactions at 60 A GeV. We have also taken the variations of correlation fluctuations and correlation strength in η and Δη space, respectively for the ring-like and jet-like structure. The average behavior of correlation parameters of ring-like events strongly differs from jet-like events due to expected Cherenkov Gluon radiation. © 2021, The Author(s), under exclusive licence to Società Italiana di Fisica and Springer-Verlag GmbH Germany, part of Springer Nature.