# Universal Nuclear Equation of State Introducing the Hypothetical X17 Boson

^{1}

^{2}

^{3}

^{*}

^{†}

## Abstract

**:**

## 1. Introduction

## 2. Tolman–Oppenheimer–Volkoff Equations and the Equation of State

## 3. Analysis Results

## 4. Conclusions

## Author Contributions

## Funding

## Institutional Review Board Statement

## Informed Consent Statement

## Data Availability Statement

## Acknowledgments

## Conflicts of Interest

## References

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**Figure 1.**(Color online). Binding energy (BE) of the ${}^{208}Pb$ versus its neutron skin using 30% admixture of the $17\phantom{\rule{3.33333pt}{0ex}}$ MeV boson in an EoS.

**Figure 2.**(Color online). The pressure as function of nuclear density for three EoSs with admixtures of 30% and 40% of the $17\phantom{\rule{3.33333pt}{0ex}}$ MeV boson plus the NL3 EoS. The parameters are defined in Table 2.

**Figure 3.**(Color online). The mass–radius relation for three EoSs plus the NL3 with admixtures of 30% and 40% of the $17\phantom{\rule{3.33333pt}{0ex}}$ MeV boson plus the NL3 EoS.

**Table 1.**Constrained parameter sets for three EoSs with three admixtures q and incompressibility K${}_{0}$ = 250 ± 20 MeV.

K${}_{0}$ | q | $\mathit{\kappa}$ | $\mathit{\lambda}$ | g${}_{\mathit{v}}$ | g${}_{\mathit{s}}$ | m${{}^{*}}_{\mathit{v}}$ [MeV] | m${}_{\mathit{\sigma}}$ [MeV] |
---|---|---|---|---|---|---|---|

235.95 | 0.3 | 21.50 | −163.33 | 8.38 | 9.20 | 547.77 | 482.16 |

269.14 | 0.4(A) | 11.00 | −50.00 | 6.85 | 7.23 | 469.55 | 391.44 |

257.50 | 0.4(B) | 11.50 | −60.00 | 6.85 | 7.23 | 469.55 | 391.44 |

**Table 2.**Polytropes for three EoSs plus the NL3 EoS used for the Tolman–Oppenheimer–Volkoff calculations. The 0.3 EoS represents a 30% admixture of the $X17$ boson and the 0.4A and 0.4B EoSs represent a 40% admixture with different values of parameters $\kappa $ and $\lambda $.

EoS q-Admixture (%) | ${\mathit{a}}_{0}$ | ${\mathsf{\Gamma}}_{1}$ | ${\mathsf{\Gamma}}_{2}$ | ${\mathsf{\Gamma}}_{3}$ | K${}_{0}$ (MeV) |
---|---|---|---|---|---|

0.3 (30%) | 34.703 | 3.741 | 3.118 | 2.497 | 235.95 |

0.4(A) (40%) | 34.673 | 3.744 | 3.036 | 2.517 | 269.14 |

0.4(B) (40%) | 34.653 | 3.643 | 3.095 | 2.540 | 257.50 |

NL3 (0%) | 34.846 | 3.872 | 2.925 | 2.394 | 332 |

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**MDPI and ACS Style**

Veselský, M.; Petousis, V.; Leja, J.; Navarro, L.
Universal Nuclear Equation of State Introducing the Hypothetical X17 Boson. *Symmetry* **2023**, *15*, 49.
https://doi.org/10.3390/sym15010049

**AMA Style**

Veselský M, Petousis V, Leja J, Navarro L.
Universal Nuclear Equation of State Introducing the Hypothetical X17 Boson. *Symmetry*. 2023; 15(1):49.
https://doi.org/10.3390/sym15010049

**Chicago/Turabian Style**

Veselský, Martin, Vlasios Petousis, Jozef Leja, and Laura Navarro.
2023. "Universal Nuclear Equation of State Introducing the Hypothetical X17 Boson" *Symmetry* 15, no. 1: 49.
https://doi.org/10.3390/sym15010049