Method for the analysis of forward-backward multiplicity correlations in heavy-ion collisions

De, S.; Tarnowsky, T.; Nayak, T. K.; Scharenberg, R. P.; Srivastava, B.

doi:10.1103/physrevc.88.044903

Cited by 16 publications

(11 citation statements)

References 27 publications

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“…Eq. (26). Moreover, various rank-3 moments shown in the plot are essentially equal to one another in the Glauber treatment.…”

Section: A Results For the Correlations Of Sourcesmentioning

confidence: 80%

“…Long-range rapidity correlations between multiplicities of produced hadrons have been under active consideration since the early experiments with pp and pp collisions [1][2][3][4], followed with heavy-ion data in the RHIC era [5][6][7]. Numerous theoretical investigations followed, in particular [8][9][10][11][12][13][14][15][16][17][18][19][20][21][22][23][24][25][26][27]. The interest is driven by the expectation that such correlations may provide understanding of the elementary space-time dynamics in the earliest (partonic) stages of the reaction.…”

Section: Introductionmentioning

confidence: 99%

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Multibin correlations in a superposition approach to relativistic heavy-ion collisions

Olszewski

Broniowski

2015

Phys. Rev. C

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Analysis of correlation of multiplicities between various rapidity bins is carried out in the framework of a superposition approach consisting of three phases of the ultra-relativistic nuclear collision: early partonic phase, intermediate collective evolution, and statistical hadronization. Simple relations between the moments of produced hadrons and the moments of the sources produced in the initial partonic phase are presented. They involve only a few effective parameters describing the microscopic dynamics of the system. We illustrate the practicality of the approach with the Glauber model simulations. Our study bears direct relevance for the interpretation of the upcoming results for the multibin multiplicity correlations from the LHC, which will help in an assessment of the correlation features of the state formed in the earliest stage of the reaction.

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“…Eq. (26). Moreover, various rank-3 moments shown in the plot are essentially equal to one another in the Glauber treatment.…”

Section: A Results For the Correlations Of Sourcesmentioning

confidence: 80%

Section: Introductionmentioning

confidence: 99%

Multibin correlations in a superposition approach to relativistic heavy-ion collisions

Olszewski

Broniowski

2015

Phys. Rev. C

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“…Early investigations of pp and pp collisions [19][20][21][22][23][24][25] and nuclear collisions [26,27] were followed by the studies of ultra-relativistic heavy-ion and pp reactions at RHIC [2,28] and at the LHC [29][30][31][32][33][34][35]. Numerous physical models and theoretical methods have been invented in attempts to understand the mechanisms behind the generation of long-range correlations [3,12,17,18,. The importance of these investigations lies in the well-known fact that the correlations over a large rapidity separation can originate only from the earliest stages of the collision, thus they may reveal fingerprints of the early dynamics of the system.…”

Section: Forward-backward Multiplicity Correlationsmentioning

confidence: 99%

“…Then, to improve statistics, one may average the obtained covariance matrices over several narrow centrality bins within a broader class. This method, essentially based on the concept of conditional correlation (see, e.g., [1]), was successfully used in the analysis by the STAR Collaboration [2], with further proposals presented in [3].…”

Section: Introductionmentioning

confidence: 99%

Partial correlation analysis method in ultrarelativistic heavy-ion collisions

Olszewski

Broniowski

2017

Phys. Rev. C

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We argue that statistical data analysis of two-particle longitudinal correlations in ultra-relativistic heavy-ion collisions may be efficiently carried out with the technique of partial covariance. In this method, the spurious event-by-event fluctuations due to imprecise centrality determination are eliminated via projecting out the component of the covariance influenced by the centrality fluctuations. We bring up the relationship of the partial covariance to the conditional covariance. Importantly, in the superposition approach, where hadrons are produced independently from a collection of sources, the framework allows us to impose centrality constraints on the number of sources rather than hadrons, that way unfolding of the trivial fluctuations from statistical hadronization and focusing better on the initial-state physics. We show, using simulated data from hydrodynamics followed with statistical hadronization, that the technique is practical and very simple to use, giving insight into the correlations generated in the initial stage. We also discuss the issues related to separation of the short-and long-range components of the correlation functions, and show that in our example the short-range component from the resonance decays is largely reduced by considering pions of the same sign. We demonstrate the method explicitly on the cases where centrality is determined with a single central control bin, or with two peripheral control bins.PACS numbers: 25.75Gz, 25.75.Ld

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“…The conditional covariance is defined by first fixing the values of Z to obtain the covariance of X i and X j , and then averaging over the control variable(s) Z. Note that the prescription of using very narrow centrality bins and then averaging over them, advocated in [9][10][11], precisely conforms to this recipe. It has been shown [10,12,13]…”

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confidence: 99%

Partial Correlation Analysis in Ultra-relativistic Nuclear Collisions

Broniówski¹,

Olszewski²

2019

Acta Phys. Pol. B Proc. Suppl.

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We show that the method of partial covariance is a very efficient way to introduce constraints (such as the centrality selection) in data analysis in ultra-relativistic nuclear collisions. The technique eliminates spurious event-by-event fluctuations of physical quantities due to fluctuations of control variables. Moreover, in the commonly used superposition approach to particle production the method can be used to impose constraints on the initial sources rather than on the finally produced particles, thus separating out the trivial fluctuations from statistical hadronization or emission from sources and focusing strictly on the initial-state physics. As illustration, we use simulated data from hydrodynamics started on the wounded-quark event-by-event initial conditions, followed with statistical hadronization, to show the practicality of the approach in analyzing the forward-backward multiplicity fluctuations. We mention generalizations to the case with several constraints and other observables, such as the transverse momentum or eccentricity correlations. This talk is based on [1] where more details can be found. The technique of partial covariance is widely used in other areas of science in situations where one can distinguish the physical variables and the control (spurious, nuisance) variables in multivariate statistical samples (see, e.g., [2,3]). Such a separation occurs in typical setups in ultra-relativistic nuclear collisions, where response of certain detectors is used to determine centrality, the quantile from a given measure quantity, which plays the role of a control variable, whereas other quantities correspond to physical variables.The problem of eliminating fluctuations of centrality, spuriously correlating to physical quantities, has a long history with numerous methods,

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Method for the analysis of forward-backward multiplicity correlations in heavy-ion collisions

Cited by 16 publications

References 27 publications

Multibin correlations in a superposition approach to relativistic heavy-ion collisions

Multibin correlations in a superposition approach to relativistic heavy-ion collisions

Partial correlation analysis method in ultrarelativistic heavy-ion collisions

Partial Correlation Analysis in Ultra-relativistic Nuclear Collisions

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