Charged Particle Multiplicity Distributions Research Articles

Multiplicity Distributions and Modified Combinants in the Multipomeron Model of pp Interaction at High Energies

The multiplicity distributions of charged particles and their combinants for pp collisions at LHC energies are studied within the Multipomeron Exchange Model (MEM) that takes into account the phenomenon of string fusion. It is shown that the use of Gaussian-type distributions for multiplicity distributions at a fixed number of pomerons allows, within the MEM framework, the reproduction of the resulting multiplicity distributions and the oscillatory behavior of combinants, found in the ALICE and CMS pp collision data at LHC energies. It is important that in the proposed approach, the parameters of these Gaussian-type distributions are not considered free, but are calculated from the two-particle correlation function of a single string.

Moments of multiplicity distributions for KNO scaling study using the ATLAS results

The normalised order-q moments of primarily charged-particle multiplicity distributions are studied for KNO scaling investigation in pp collisions as deduced from the results of the ATLAS at the LHC. The normalised moments for the LHC and low-energy experiments are compared for the kinematic region with an absolute pseudorapidity less than 2.5. The normalised moments show a increases linearly with centre-of-mass energies, and therefore the KNO scaling is violated for the full-scaled multiplicity region. The normalised moments for scaled multiplicity greater than one average multiplicity are constant for the highest centre-of-mass energies, and therefore the KNO scaling is concluded to hold.

Pseudorapidity, transverse momentum and multiplicity distributions of charged particles in pp collisions at 13 TeV

Pseudorapidity, transverse momentum and multiplicity distributions of charged particles in pp collisions at 13 TeV

Imprints of clustering in multiplicity fluctuations

In this paper, we investigate the multiplicity fluctuations of charged particles observed in high-energy nuclear collisions and relate them to the size of hadronizing systems which happen during such processes. We use the average multiplicities langle Nrangle and variances Varleft( Nright) of multiplicity distributions of charged particles produced in centrality selected collisions of relativistic heavy-ion nuclei to evaluate the dynamic variance varOmega and study its dependence on the size of colliding systems. We connect the observed system-size dependence of multiplicity fluctuations with the clustering phenomena and the finiteness of the hadronizing sources and the thermal bath.

QGP generation and evolution simulation of pp collision on LHC

In this paper, the generation of Quark-Gluon Plasma(QGP) in proton–proton collisions is discussed based on the thermal equilibrium theory. A partons list at the initial stage of collisions are obtained by digital sampling method, which provides a reasonable initial state for the subsequent evolution simulation. The calculation shows that the multiplicity distribution of the final charged particles obtained by this method is very similar to that of experiment or PYTHIA event generator. Thus, a new mechanism for hadron production in LHC is proposed.

Modeling of charged-particle multiplicity and transverse-momentum distributions in pp collisions using a DNN

A machine learning technique is used to fit multiplicity distributions in high energy proton-proton collisions and applied to make predictions for collisions at higher energies. The method is tested with Monte Carlo event generators. Charged-particle multiplicity and transverse-momentum distributions within different pseudorapidity intervals in proton-proton collisions were simulated using the PYTHIA event generator for center of mass energies sqrt{s}= 0.9, 2.36, 2.76, 5, 7, 8, 13 TeV for model training and validation and at 10, 20, 27, 50, 100 and 150 TeV for model predictions. Comparisons are made in order to ensure the model reproduces the relation between input variables and output distributions for the charged particle multiplicity and transverse-momentum. The multiplicity and transverse-momentum distributions are described and predicted very well, not only in the case of the trained but also in the case of untrained energy values. The study proposes a way to predict multiplicity distributions at a new energy by extrapolating the information inherent in the lower energy data. Using real data instead of Monte Carlo, as measured at the LHC, the technique has the potential to project the multiplicity distributions for different intervals at very high collision energies, e.g. 27 TeV or 100 TeV for the upgraded HE-LHC and FCC-hh respectively, using only data collected at the LHC, i.e. at center of mass energies from 0.9 up to 13 TeV.

Study of the KNO scaling in pp collisions at sqrt{s} from 0.9 to 13 TeV using results of the ATLAS at the LHC

The comparisons of the charged-particle multiplicity and the average transverse momentum distributions on the scaled multiplicity, KNO scale, using the results of the ATLAS collaboration at the LHC are presented. These distributions were measured in proton–proton collisions at centre-of-mass energies from 0.9 to 13 TeV for the absolute pseudorapidity region less than 2.5 and two samples of events with each charged-particle transverse momentum greater than 100 and 500 MeV, respectively. The shape evolution of the multiplicity distributions with a collision energy is studied in terms of KNO scaling variables. The charged-particle multiplicity distributions on the KNO scale have the similar shape and decrease with increasing collision energy. The KNO distributions tend to be independent of energy for the highest energies. The average transverse momentum distributions on the KNO scale have a similar shape and increase with increasing collision energy.

Multiplicity Distribution and KNO Scaling of Charged Particles Production from pp Collisions at Different Energies

The multiplicity distribution of charged particles produced from proton–proton collisions at energies s = 2.36, 2.76, 5, 7, 8, 10, 13 and 14 TeV were studied in the present work. Furthermore, multiplicity distribution was studied in different pseudorapidity regions ∣η∣ < 0.5, 1, 1.5, 2, and 2.5. KNO scaling was studied at the same pseudorapidity regions. This is valid in the pseudorapidity region ∣η∣ < 0.5, but with increasing pseudorapidity, the violation increases. The influence of MPI and color reconnection in violation of KNO scaling were studied. The relation between mean multiplicity and collisions energy was explored, noted that it increases with the increasing energy of collisions.

Sub-Poissonian multiplicity distributions in jets produced in hadron collisions

In this work we show that the proper analysis and interpretation of the experimental data on the multiplicity distributions of charged particles produced in jets measured in the ATLAS experiment at the LHC indicates their sub-Poissonian nature. We also show how, by using the recurrence relations and combinants of these distributions, one can obtain new and otherwise unavailable information contained in them, which may broaden our knowledge of the particle production mechanism.

Dynamics of particle production in Pb-Pb collisions at sNN=2.76 TeV using the PYTHIA8 Angantyr model

We study the dynamics of identified, strange, and multistrange particle production in Pb-Pb collisions at $\sqrt{{s}_{NN}}$ = 2.76 TeV using the recently developed Angantyr model, incorporated within pythia8. We show the interplay between multiparton interactions (MPIs) and color reconnection (CR) on the experimentally measured quantities. We also investigate the role of string shoving within the rope hadronization framework and its impact in particle production. The charged-particle multiplicity (${N}_{\mathrm{ch}}$) and mean transverse momentum ($\ensuremath{\langle}{p}_{\mathrm{T}}\ensuremath{\rangle}$) distributions are well explained by pythia8 Angantyr with proper tuning, as presented in this paper. Predictions of ${p}_{\mathrm{T}}$ spectra, $\ensuremath{\langle}{p}_{\mathrm{T}}\ensuremath{\rangle}$, and ${p}_{\mathrm{T}}$ integrated yields of the identified, strange, and multistrange particles are studied. To provide insight into the collective nature of the produced particles, we look into the ratio of particle yields to pions and kaons. pythia8 Angantyr with MPI$+$CR and hadronization via string shoving is seen to mimic signs of collectivity due to different implementations in string interactions.

Properties of charged particle multiplicities in anti-neutrino interactions of the CHORUS experiment

In this study, the charged particle multiplicity distribution produced in anti-neutrino interactions in nuclear emulsion is investigated in terms of the log-normal parametric model and KNO-G scaling for the first time. The results are based on the data collected by the CHORUS experiment in the nu _{mu } beam from CERN SPS. The analysis of 369 bar{nu }_{mu }CC events showed that anti-neutrino charged-particle multiplicity data shape is well described by a log-normal distribution. Furthermore, KNO-G scaling has been successfully applied to the data and results confirm the validity of KNO-G scaling for the anti-neutrino interactions. Finally, results are presented in detail in the form of figures and tables.

Statistical Scrutiny of Particle Spectra in ep Collisions

Charged particle multiplicity distributions in positron–proton deep inelastic scattering at a centre-of-mass energy s = 300 GeV, measured in the hadronic centre-of-mass frames and in different pseudorapidity windows are studied in the framework of two statistical distributions, the shifted Gompertz distribution and the Weibull distribution. Normalised moments, normalised factorial moments and the H-moments of the multiplicity distributions are determined. The phenomenon of oscillatory behaviour of the counting statistics and the Koba-Nielsen-Olesen (KNO) scaling behaviour are investigated. This is the first such analysis using these data. In addition, projections of the two distributions for the expected average charged multiplicities obtainable at the proposed future ep colliders.

Log-normal and Negative Binomial Distributions of DONUT Data

There are several parametric models to describe the charged particle multiplicity distributions in literature. Among them, log-normal distribution and negative binomial distribution are the most well-known parametric models. In this study, negative binomial and log-normal distributions are compared and tested in neutrino interactions produced in DONUT experiment. This analysis was carried out using the real experimental results of the DONUT Collaboration. The results of the analysis show that the neutrino data, reported by DONUT collaboration, is well described by negative binomial and log-normal distribution. In terms of fit parameters, the χ/ndf value of the both distribution NBD and LND are close to unity but log-normal distribution data slightly better than negative binomial distribution.

Measurement of charged particle multiplicity distributions in DIS at HERA and its implication to entanglement entropy of partons

Charged particle multiplicity distributions in positron-proton deep inelastic scattering at a centre-of-mass energy sqrt{s}=319 GeV are measured. The data are collected with the H1 detector at HERA corresponding to an integrated luminosity of 136 pb^{-1}. Charged particle multiplicities are measured as a function of photon virtuality Q^2, inelasticity y and pseudorapidity eta in the laboratory and the hadronic centre-of-mass frames. Predictions from different Monte Carlo models are compared to the data. The first and second moments of the multiplicity distributions are determined and the KNO scaling behaviour is investigated. The multiplicity distributions as a function of Q^2 and the Bjorken variable x_{mathrm{bj}} are converted to the hadron entropy S_{mathrm{hadron}}, and predictions from a quantum entanglement model are tested.

The nuclear effect analysis in relativistic heavy ion collisions at BNL energies

In this article, an attempt has been made to understand the behavior of the secondary charged particles multiplicity distributions produced during the heavy ion collisions at ultra-relativistic energies by using the Hurst exponent of the two dimensional (2D) factorial moments, Fq. For this purpose the experimental data have been analyzed by using the “Hurst exponent” in the original intermittency formula by considering different values of Hurst exponent (H = 1.0, 1.5, 2.0, 2.5). The investigations reveal the power-law behavior, exhibited in self-affine or nuclear effect analysis, better than that in the self-similar analysis. Finally, the described works were found very much significant and also it was within good agreement with some other works.

The nuclear effect analysis in relativistic heavy ion collisions at BNL energies

In this article, an attempt has been made to understand the behavior of the secondary charged particles multiplicity distributions produced during the heavy ion collisions at ultra-relativistic energies by using the Hurst exponent of the two dimensional (2D) factorial moments, F q . For this purpose the experimental data have been analyzed by using the “Hurst exponent” in the original intermittency formula by considering different values of Hurst exponent (H = 1.0, 1.5, 2.0, 2.5). The investigations reveal the power law behavior, exhibited in self-affine or nuclear effect analysis, better than that in self-similar analysis. Finally, the described works were found very much significant and also it was within good agreement with some other works.

Charged particle production in pp collisions at s = 8, 7 and 2.76 TeV at the LHC-a case study

We analyze the charged-particle multiplicity distributions measured by the ALICE experiment, over a wide pseudorapidity range, for [Formula: see text] collisions at [Formula: see text], 7 and 2.76 TeV at the LHC. The analysis offers an understanding of particle production in high energy collisions in the purview of a new distribution, the shifted Gompertz distribution. Data are compared with the distribution and moments of the distributions are calculated. A modified version of the distribution is also proposed and used to improve the description of the data consisting of two different event classes: the inelastic and the nonsingle diffractive and their subsets in different windows of pseudorapidity, [Formula: see text]. The distribution used to analyze the data has a wide range of applicability to processes in different fields and complements the analysis done by the ALICE collaboration in terms of various LHC event generators and IP-Glasma calculations.

Multiplicity and pseudo-rapidity density distributions of charged particles produced in pp, pA and AA collisions at RHIC & LHC energies

Multiplicity and pseudorapidity (η) density (dN ch/dη) distributions of charged hadrons provide key information towards understanding the particle production mechanisms and initial conditions of high-energy heavy-ion collisions. However, detector constraints limit the η-range across which charged particle measurements can be carried out. Extrapolating the measured distributions to large η-range by parameterizing measured distributions and by using calculations from event generators, we characterize the production of charged particles over the full kinematic range. In the present study, we use three different anstze to obtain quantitative descriptions of the shape of pseudorapidity distributions of charged hadrons produced in pp, p–A, and A–A collisions for beam energies () ranging from a few GeV to a few TeV corresponding to RHIC and LHC energies. We study the limiting fragmentation behavior in these collisions and report evidence for participant-scaling violations in high-energy collisions at the TeV scale. We additionally examine measured pseudorapidity distributions to constrain models describing initial conditions of particle production. We predict the centrality dependence of charged particle multiplicity distributions at FAIR and NICA energies and give an estimation of charged particle multiplicity at η = 0 for the proposed HE-LHC and FCC energies.

Modeling charged-particle multiplicity distributions at LHC

With many applications in high-energy physics, Deep Learning or Deep Neural Network (DNN) has become noticeable and practical in recent years. In this article, a new technique is presented for modeling the charged particles multiplicity distribution [Formula: see text] of Proton-Proton [Formula: see text] collisions using an efficient DNN model. The charged particles multiplicity n, the total center of mass energy [Formula: see text], and the pseudorapidity [Formula: see text] used as input in DNN model and the desired output is [Formula: see text]. DNN was trained to build a function, which studies the relationship between [Formula: see text]. The DNN model showed a high degree of consistency in matching the data distributions. The DNN model is used to predict with [Formula: see text] not included in the training set. The expected [Formula: see text] had effectively merged the experimental data and the values expected indicate a strong agreement with Large Hadron Collider (LHC) for ATLAS measurement at [Formula: see text], 7 and 8 TeV.

Inclusive charged and neutral particle multiplicity distributions in χcJ and J/ψ decays

Using a sample of 106 million $\psi(3686)$ decays, $\psi(3686) \to \gamma \chi_{cJ} (J = 0, 1, 2)$ and $\psi(3686) \to \gamma \chi_{cJ}, \chi_{cJ} \to \gamma J/\psi$ $(J = 1, 2)$ events are utilized to study inclusive $\chi_{cJ} \to$ anything, $\chi_{cJ} \to$ hadrons, and $J/\psi \to$ anything distributions, including distributions of the number of charged tracks, electromagnetic calorimeter showers, and $\pi^0$s, and to compare them with distributions obtained from the BESIII Monte Carlo simulation. Information from each Monte Carlo simulated decay event is used to construct matrices connecting the detected distributions to the input predetection "produced" distributions. Assuming these matrices also apply to data, they are used to predict the analogous produced distributions of the decay events. Using these, the charged particle multiplicities are compared with results from MARK I. Further, comparison of the distributions of the number of photons in data with those in Monte Carlo simulation indicates that G-parity conservation should be taken into consideration in the simulation.