Intermittency and related issues in ¹⁶O-Ag/Br collision at 200A GeV/c

Abstract

In this paper we present some results on the nonstatistical fluctuation in the 1-dimensional (1-d) density distribution of singly charged produced particles in the framework of the intermittency phenomenon. A set of nuclear emulsion data on 16 O-Ag/Br interactions at an incident momentum of 200A GeV/c, was analyzed in terms of different statistical methods that are related to the self-similar fractal properties of the particle density function. A comparison of the present experiment with a similar experiment induced by the 32 S nuclei and also with a set of results simulated by the Lund Monte Carlo code FRITIOF is presented. A similar comparison between this experiment and a pseudo-random number generated simulated data set is also made. The analysis reveals the presence of a weak intermittency in the 1-d phase space distribution of the produced particles. The results also indicate the occurrence of a nonthermal phase transition during emission of final-state hadrons. Our results on factorial correlators suggests that short-range correlations are present in the angular distribution of charged hadrons, whereas those on oscillatory moments show that such correlations are not restricted only to a few particles. In almost all cases, the simulated results fail to replicate their experimental counterparts. PACS Nos: 25.75-q, 25.70 Mn, 24.60 Ky Résumé : Nous présentons ici des résultats sur les fluctuations non statistiques des distribution de densités en 1-D (une dimension) des particules à une charge produites dans des phénomènes intermittents. Nous avons analysé un ensemble de données sur émulsions nucléaires résultant d'interactions 16 O-Ag/Br avec une quantité de mouvement incidente de 200AGeV/c, à partir des différentes méthodes statistiques reliées aux propriétés fractales auto-similaires de la fonction de densité de particule. Nous comparons le présent travail avec d'autres expériences similaires induites par le noyau 32 S, et aussi avec un ensemble de résultats simulés à l'aide du programme Monte Carlo de Lund, FRITIOF. Dans certaines cas, de semblables comparaisons ont été faites entre l'expérience et des ensembles de données simulées par génération de nombres (pseudo) au hasard. L'analyse révèle la présence d'une faible intermittence dans la distribution dans l'espace de phase à 1-D des particules produites. Les résultats indiquent également la présence d'une transition de phase non thermique pendant l'émission des hadrons de l'état final. Nos données sur les corrélateurs factoriels suggèrent que des corrélations à courte portée jouent un rle dans la distribution angulaire des hadrons chargés, alors que celles sur les moments oscillants montrent que de telles corrélations ne sont pas limitées à quelques particules. Dans presque tous les cas, les simulations n'ont pas réussi à reproduire les résultats expérimentaux.[Traduit par la Rédaction]

Intermittency and erraticity of charged particles produced in 28Si-Ag/Br interaction at 14.5 A GeV

“…It is also dependent on the choice of the phase space variable, which, to a certain extent is in contradiction to the observation of ref. 24, but is consistent with our previous observations on AB interactions [16,17].…”

“…These values are about 1/6 times the maximum fluctuation strength (a = 1.0) allowed in the a model. Comparing with our previous results, we find that the present values are smaller than those obtained in 16 O-Ag/Br interaction at 200 A GeV/c (about 1/4 of the maximum value), but within error are of the same magnitude as the 32 S-Ag/Br interaction at 200 A GeV/c [16,17]. Thus, it appears that, for the same target, the fluctuation strength depends more on the mass number than on the energy of the incident projectile.…”

“…This is true in both h-and 4-spaces. At this point we may note that the string fragmentation model FRITIOF [22] also did not show any intermittency for AB interactions at 200 A GeV/c [16,17]. The values of the intermittency index along with the Pearson's R 2 coefficients, which indicate the goodness of fit [23], are shown in Table 1.…”

“…We have also performed the erraticity analysis on a purely statistical sample generated by random numbers. On several occasions, results of the present analysis are also compared with the results of other similar experiments on AB interactions [12,[14][15][16][17].…”

“…To conserve transverse momentum, the particles probably experience extra correlation in the azimuthal plane. However, such differences in the f q values are more prominent in interactions induced by nuclei with higher mass numbers (e.g., 28 Si or 32 S [16]) and are smaller when the interaction is induced by a comparatively lighter ( 16 O) nucleus [17]. Results of the present investigation differ significantly from those obtained from the analyses of another set of 28 Si-Ag/Br data at the same incident energy (14.5 A GeV) as in the present case [14,15].…”