Quark degrees of freedom in the production of soft pion jets

Abstract

Experimental results obtained by studying the properties of soft jets in the 4-velocity space at √ s ∼ 2 to 20 GeV are presented. The changes in the mean distance from the jet axis to the jet particles, the mean kinetic energy of these particles, and the cluster dimension in response to the growth of the collision energy are consistent with the assumption that quark degrees of freedom manifest themselves in processes of pion-jet production at intermediate energies. The energy at which quark degrees of freedom begin to manifest themselves experimentally in the production of soft pion jets is estimated for the first time. The estimated value of this energy is 2.8 ± 0.6 GeV.

NICA fixed target mode: Soft jet studies in the relative 4-velocity space

“…1c, d) and confirms the hypothesis with regard to the changing of the dynamical regimes of multiparticle production at √ s ∼ 5 GeV [4]. [6,7]. A universal lower boundary for the manifestation of jet geometry for final states was qualitatively estimated in [14] at √ s l ∼ 3 GeV for multiparticle-production processes.…”

“…There is a substantial improvement of the quality of fits for any fragmentation region and any value ofX (χ 2 /ndf ∼ 3 − 5). Statistically acceptable values of χ 2 /ndf could be obtained for 45% of the samples [6,7]. Numerical values found for √ s c from a fit to G i ( √ s) for √ s < 4 GeV are summarized in the Table 1, the values corresponded to the fits of b k energy dependence being taken from [5].…”

“…Figure 1 gives the parameters from the set G versus √ s for various interactions at X = 0.1 (a, c, e) and X = 0.2 (b, d, f). The experimental-data array from [6,7] is under study and various samples of these data are approximated by the functions…”

“…For D, the fit quality is indicative of only qualitative agreement between the function in (1) and experimental data at either value of X (see Figs. 1e, f) [6,7]. In the Table 1, the values obtained for √ s c from a fit in the region of √ s > 2 GeV for global samples and for individual samples in the target-and beam fragmentation regions are given in the second rows for T k and D. The experimental results for the traditional definition of the thermal freeze-out temperature (T ) obtained for pp collisions at √ s ≈ 6 − 18 GeV [12] agrees quite reasonably with T k ( √ s) at soft X = 0.1 (see Fig.…”

“…. Special features of this method in the case of the production of two jets were considered in detail in [3,4,5,6,7]. In that case, secondary particles refer to the region of target (beam) fragmentation if…”