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Forward-Backward Correlations and Multiplicity Fluctuations in Pb–Pb Collisions at √s_{NN} = 2.76 TeV from ALICE at the LHC^{ †}

^{†}

## Abstract

**:**

## 1. Introduction

## 2. Analysis Details

## 3. Results and Discussion

#### 3.1. Forward-Backward Correlation Coefficient ${b}_{corr}^{n-n}$

- (a)
- In all panels of Figure 1 a significant decrease of the correlation strength with decreasing size of the centrality class interval (from $10\%$ to $1\%$) is observed, regardless of the chosen centrality selection method.
- (b)
- There is an evident dependence of the forward-backward correlation coefficient ${b}_{corr}^{n-n}$ on the centrality selection method. This is valid for all studied centrality classes of Pb–Pb collisions.

#### 3.2. Strongly Intensive Quantity $\Sigma $

- (a)
- Contrary to the results obtained for the FB correlation coefficient ${b}_{corr}^{n-n}$, the data points measured for the $\Sigma $ observable appear unaffected by the reduction of centrality bin size. This behavior characterizes both the experimental data and MC HIJING results, regardless of the chosen centrality estimator. This implies that $\Sigma $ is insensitive to geometrical fluctuations.
- (b)
- From the comparison between right and left panels of Figure 2a,b, it is evident that the $\Sigma $ observable is insensitive to the centrality selection method.

## 4. Conclusions

## Funding

## Conflicts of Interest

## References

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**Figure 1.**The forward-backward correlation coefficient ${b}_{corr}^{n-n}$ obtained for (

**a**) experimental data and (

**b**) HIJING generated Pb–Pb collisions at $\sqrt{{s}_{\mathrm{NN}}}=2.76$ TeV, drawn as a function of centrality class size ($\Delta centrality$), for a fixed value of the pseudorapidity gap $\Delta \eta =1.2$. The results are obtained for different centrality selection methods: via ZDCvsZEM, via V0 and via impact parameter selection. The width of the centrality class changes from $1\%$ to $10\%$. The different colors of the data points correspond to different centralities of the Pb–Pb collision. Systematic uncertainties are shown as rectangles, statistical uncertainties are smaller than marker sizes.

**Figure 2.**The $\Sigma $ observable obtained for (

**a**) experimental data and (

**b**) HIJING generated Pb–Pb collisions at $\sqrt{{s}_{\mathrm{NN}}}=2.76$ TeV, drawn as a function of centrality class size ($\Delta centrality$), for a fixed value of the pseudorapidity gap $\Delta \eta =1.2$. The results are obtained for different centrality selection methods: via ZDCvsZEM, via V0 and via impact parameter selection. The width of the centrality class changes from $1\%$ to $10\%$. The different colors of the data points correspond to different centralities of the Pb–Pb collision. Systematic uncertainties are shown as rectangles, statistical uncertainties are labeled with vertical lines.

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**MDPI and ACS Style**

Sputowska, I.
Forward-Backward Correlations and Multiplicity Fluctuations in Pb–Pb Collisions at √*s*_{NN} = 2.76 TeV from ALICE at the LHC. *Proceedings* **2019**, *10*, 14.
https://doi.org/10.3390/proceedings2019010014

**AMA Style**

Sputowska I.
Forward-Backward Correlations and Multiplicity Fluctuations in Pb–Pb Collisions at √*s*_{NN} = 2.76 TeV from ALICE at the LHC. *Proceedings*. 2019; 10(1):14.
https://doi.org/10.3390/proceedings2019010014

**Chicago/Turabian Style**

Sputowska, Iwona.
2019. "Forward-Backward Correlations and Multiplicity Fluctuations in Pb–Pb Collisions at √*s*_{NN} = 2.76 TeV from ALICE at the LHC" *Proceedings* 10, no. 1: 14.
https://doi.org/10.3390/proceedings2019010014