# The 24th International Spin Symposium

18-22 October 2021
Matsue, Shimane Prefecture, Japan
Asia/Tokyo timezone

## Dipole polarizability from small-angle proton scattering and implications for symmetry energy properties and the formation of neutron skins

18 Oct 2021, 16:40
30m
Matsue, Shimane Prefecture, Japan

#### Matsue, Shimane Prefecture, Japan

Matsue City, Shimane Prefecture, Japan
Plenary Presentation (by invitation only) Plenary presentations

### Speaker

Peter von Neumann-Cosel (Institut fur Kernphysik, TU Darmstadt)

### Description

The dipole polarizability of nuclei carries information on the density dependence of the symmetry energy governing the properties of the Equation of State of neutron-rich matter relevant to neutron stars and core-collapse supernovae. In recent years, zero-degree polarized proton scattering has been developed at RCNP as an experimental tool to measure the dipole polarizability [1]. Such data also provide constraints on the neutron skin thickness of heavy nuclei [2]. A recent study of $^{40}$Ca together with results from a previous experiment on $^{48}$Ca [3] serve as a test of state-of-the-art ab initio [4,5] and energy densitiy functional [6] calculations. From the good agreement obtained for both methods one can set limits on the density dependence of the symmetry energy. These are clearly at variance with those derived [7] from the recently published result of the PREX-II experiment [8].

[1] P. von Neumann-Cosel and A. Tamii, Eur. Phys. J. A 55, 110 (2019).
[2] A. Tamii et al., Phys. Rev. Lett. 107, 262502 (2011).
[3] J. Birkhan et al., Phys. Rev. Lett. 118, 252501 (2017).
[4] J. Simonis, S. Bacca, and G. Hagen, Eur. Phys. J. A 55, 241 (2019).
[5] S. Kaufmann et al., Phys. Rev. Lett. 124, 132502 (2020).
[6] P.-G. Reinhard, X. Roca-Maza, and W. Nazarewicz, arXiv:2105.15050.
[7] B.T. Reed, F.J. Fattoyev, C.J. Horowitz, and J. Piekarewicz, Phys. Rev. Lett. 126, 172503 (2021).
[8] D. Adhikari et al., Phys. Rev. Lett. 126, 172502 (2021).

### Primary author

Peter von Neumann-Cosel (Institut fur Kernphysik, TU Darmstadt)

### Presentation Materials

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