Universality in energy dependence of the average charged particle multiplicity for e+e− and p±p collisions

Chliapnikov, P.; Uvarov, V.

doi:10.1016/0370-2693(90)90252-2

Cited by 26 publications

(25 citation statements)

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“…the effective 1/3 energy in hadronic interactions. Earlier, the factor 1/3 has been already shown to provide an agreement in e + e − and pp/p p mean multiplicity data [23]; for a discussion, see [13]. Such a universality is found to correctly predict [15,16] the value of the midrapidity density in pp interactions at the TeV LHC energies [24].…”

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confidence: 78%

Effective-energy budget in multiparticle production in nuclear collisions

et al. 2014

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The dependencies of charged particle pseudorapidity density and transverse energy pseudorapidity density at midrapidity on the collision energy and on the number of nucleon participants, or centrality, measured in nucleusnucleus collisions are studied in the energy range spanning a few GeV to a few TeV per nucleon. The approach in which the multiparticle production is driven by the dissipating effective energy of participants is introduced. This approach is based on the earlier proposed consideration, combining the constituent quark picture together with Landau relativistic hydrodynamics shown to interrelate the measurements from different types of collisions. Within this picture, the dependence on the number of participants in heavy-ion collisions are found to be well described in terms of the effective energy defined as a centrality-dependent fraction of the collision energy. For both variables under study, the effective-energy approach reveals a similarity in the energy dependence obtained for the most central collisions and centrality data in the entire available energy range. Predictions are made for the investigated dependencies for the forthcoming higher-energy measurements in heavy-ion collisions at the LHC. 1.Multiparticle production in high-energy particle and nuclear collisions attracts high interest, as, on the one hand, the observables measured first in high-energy collisions, namely multiplicity and transverse energy, are immediate characteristics of this process and bring important information on the underlying dynamics of strong interactions, while on the other hand, this process still eludes its complete understanding. It is already more than half a century as the multia e-mail: Aditya.Nath.Mishra@cern.ch b e-mail: Raghunath.Sahoo@cern.ch c e-mail: sedward@mail.cern.ch d e-mail: Alexandre.Sakharov@cern.ch plicity of the produced particles are considered to be derived by the collision energy [1][2][3]. In this picture the energy pumped into the collision zone in the very first stage of the collision defines the volume of the interaction lump of participant patterns. Later on, the approach of "wounded" nucleons, or nucleon participants, has been proposed to describe the multiplicity and particle distributions [4]; for a review, see [5]. In this approach the multiplicity is expected to be proportional to the number of participants. However, it was observed at RHIC and similarly at LHC energies, the concept of wounded nucleons does not describe the measurements where the data found to demonstrate an increase with the number of nucleon participants. The problem has been addressed in the nuclear overlap model using Monte Carlo simulation in the constituent quark framework, and the scaling has been shown to be restored [6][7][8][9][10][11]. In addition, it was observed that the multiplicity and midrapidity-density distributions are similar in e + e − and in the most central (headon) nuclear collisions [12] at the same center-of-mass (c.m.) energy pointing to the universality of multihadron pro...

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confidence: 78%

Effective-energy budget in multiparticle production in nuclear collisions

et al. 2014

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“…The dashed curve corresponds to a t to e + e data of dierent centre-of-mass energies published in Ref. [136], where it is claimed that e + e and p p data can be described with the same phenomenological parameterization. The peak positions of the distribution have been measured by experiments at LEP and by colliders with lower centre-of-mass energies.…”

Section: Dependence On Centre-of-mass Energymentioning

confidence: 99%

Inclusive particle production in hadronic decays of the Z boson at LEP I

Böhrer

1997

Physics Reports

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Inclusive particle production in hadronic events taken at the Z resonance with LEP I is reviewed. With approximately 20 million Z decays, the four LEP experiments have studied the fragmentation of partons into identied particles. The high statistics allows for a detailed study of this non-perturbative QCD process. In this review the measurements of the four experiments are collected and the momentum spectra are compared to Monte Carlo models. More detailed aspects, such as relative production rates, particle content in gluon jets, particle correlation etc., are also treated.This review represents the`Habilitationsschrift', which has been submitted to the Physics Department at the Universit at-GH Siegen, D-57068 Siegen.

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“…The universality in energy dependence of the average charged particle multiplicities in e + e annihilation and (p= p)p collisions [6] imply that the hadron production rates are dominantly determined by some quite simple characteristics such as longitudinal phase space and available energy, the hadron masses, isospins and spins.…”

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Striking regularity in meson and baryon production rates in e+e− annihilations

Chliapnikov

Uvarov

1995

Physics Letters B

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It is shown that e + e data on the production rates of all particles (apart from pions) belonging to the SU(3) nonets of the pseudoscalar and vector mesons and, to the octet and decuplet of the baryons are determined only by particle spins, isospins and their masses. Contrary to a general belief and popular models, such as the Jetset model, the 2J + 1 spin counting factor works perfectly. The meson and baryon production rates at Z 0 pole at LEP as a function of particle mass squared lie on the one universal curve described by a simple formula < N ( particle) > = 2J+1 2Im+1 a exp( bM 2 ) with parameters a = 1 1 : 28 0:31 and b = 3 : 872 0:027 (GeV/c 2 ) 2 and 2 =N D F = 15/10, where I m is isospin for baryons or modied isospin I m for mesons introduced in this paper. Similar universal dependence with the same value of the slope b is observed at PETRA and PEP energies.To be submitted to Phys. Lett. B 1 Hadron production in Z 0 decays proceeds through two main steps: parton shower development from the primary q q pair produced from the Z 0 , followed by fragmentation of the coloured partons into colorless hadrons. The rst is well described by QCD, the theory of strong interactions. However, perturbative QCD is not applicable to the soft processes of hadronization. The formation of hadrons, mesons and baryons, out of quarks and gluons has been studied in many experiments in an attempt to understand the hadronization process better and to test phenomenological models of parton fragmentation. The most successful of these models are the string [1] and the cluster fragmentation [2] models implemented in the widely used Monte Carlo programs Jetset 7.4 PS [3] and Herwig 5.8 [4] respectively. H o w ever, the number of parameters in these models is quite large. Thus in the Jetset model many parameters control production of pseudoscalar and vector mesons. The most important are the suppression of s quark pair production compared with u or d pair production, the probability that a light meson (containing u and d quarks) has spin 1 and the probability that a strange meson has spin 1.The treatment of baryon production in e + e annihilations by the existing hadronization models is based on the experimental observations at PETRA and PEP energies that the dierential momentum spectra of mesons and baryons are rather similar. This justies the diquark model in which the fragmentation functions for baryons and mesons are assumed to be almost the same, quark-antiquark and diquark-antidiquark pairs are produced from the sea and a diquark combines with a quark to form a baryon. The relative production rates of the dierent octet and decuplet baryons are again controlled by free parameters tuned to the experimental data. The number of such parameters is also large. Thus in the Jetset model, the parameters relevant to octet and decuplet baryon production include the diquark to quark ratio (qq=q), the strange to non-strange quark ratio ((s=d), the same as used for the mesons), the strange diquark suppression factor (us=ud) (d=s), t...

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Universality in energy dependence of the average charged particle multiplicity for e+e− and p±p collisions

Cited by 26 publications

References 14 publications

Effective-energy budget in multiparticle production in nuclear collisions

Effective-energy budget in multiparticle production in nuclear collisions

Inclusive particle production in hadronic decays of the Z boson at LEP I

Striking regularity in meson and baryon production rates in e+e− annihilations

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