# Femtoscopic Correlation Measurement with Symmetric Lévy-Type Source at NA61/SHINE

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## Abstract

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## 1. Introduction

## 2. Femtoscopy with Lévy Shaped Sources

## 3. Measurement Details

## 4. Results

## 5. Conclusions

## Funding

## Data Availability Statement

## Acknowledgments

## Conflicts of Interest

## Abbreviations

QCD | quantum chromodynamics |

CERN | Conseil européen pour la recherche nucléaire |

SPS | Super Proton Synchrotron |

HBT | Hanbury Brown and Twiss |

BE | Bose-Einstein |

CEP | critical endpoint |

NA61/SHINE | North Area 61 / SPS Heavy Ion and Neutrino Experiment |

LCMS | Longitudinally Co-Moving System |

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**Figure 2.**Example fit with Bose–Einstein correlation function at ${K}_{T}=0.25$–$0.30$ GeV/c for the sum $\left(\right)open="("\; close=")">{\pi}^{+}+{\pi}^{+}$. Blue points with error bars represent the data, the green dash-dotted line shows the fitted function with Coulomb correction given by Equation (11) within the range of 0.0525 GeV/c to 0.2 GeV/c and red dashed line represent normalization to background 0.2 GeV/c to 0.4 GeV/c. In the low-q region, the black dotted line indicates the extrapolated function outside of the fit range due to prominent detector resolution effects, mentioned in the text.

**Figure 3.**The Lévy stability index, $\alpha $, for 0–10% central Ar+Sc at 150A GeV/c, as a function of ${m}_{T}$. Special cases corresponding to a Gaussian ($\alpha =2$) or a Cauchy ($\alpha =1$) source are shown, as well as $\alpha =0.5$, the conjectured value corresponding to the critical endpoint. Boxes denote systematic uncertainties, bars represent statistical uncertainties.

**Figure 4.**The radial scale parameter, R, for 0–10% central Ar+Sc at 150A GeV/c, as a function of ${m}_{T}$. Boxes denote systematic uncertainties, bars represent statistical uncertainties.

**Figure 5.**The correlation strength parameter, $\lambda $, for 0–10% central Ar+Sc at 150A GeV/c, as a function of ${m}_{T}$. Boxes denote systematic uncertainties, bars represent statistical uncertainties.

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**MDPI and ACS Style**

Pórfy, B., on behalf of the NA61/SHINE Collaboration.
Femtoscopic Correlation Measurement with Symmetric Lévy-Type Source at NA61/SHINE. *Universe* **2023**, *9*, 298.
https://doi.org/10.3390/universe9070298

**AMA Style**

Pórfy B on behalf of the NA61/SHINE Collaboration.
Femtoscopic Correlation Measurement with Symmetric Lévy-Type Source at NA61/SHINE. *Universe*. 2023; 9(7):298.
https://doi.org/10.3390/universe9070298

**Chicago/Turabian Style**

Pórfy, Barnabás on behalf of the NA61/SHINE Collaboration.
2023. "Femtoscopic Correlation Measurement with Symmetric Lévy-Type Source at NA61/SHINE" *Universe* 9, no. 7: 298.
https://doi.org/10.3390/universe9070298