Exploring the Mass Radius of $^4$He and Implications for Nuclear Structure

Rong Wang; Chengdong Han; Xurong Chen

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arXiv · 2309.01416

Exploring the Mass Radius of $^4$He and Implications for Nuclear Structure

Rong Wang·Chengdong Han·Xurong Chen

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Abstract

In this study, we determine the mass radius of $^4$He, a very light nucleus, by examining the near-threshold $\phi$-meson photoproduction data of the LEPS Collaboration. To assess the gravitational form factor of $^4$He, we employ multiple models for the mass distribution, including Yukawa-type, exponential, Gaussian, and uniform functions. The mass radius of $^4$He is measured to be $1.70\pm0.14$ fm, which is approximately equal to the charge radius of $^4$He. Surprisingly, in contrast to the findings of the proton, no noticeable discrepancy between the charge radius and the mass radius is noted for the $^4$He nucleus. The proton and neutron distributions within $^4$He are likely to be identical, confirming its regular tetrahedral structure in a new way. We propose exploring the difference between charge and mass radii as a new approach to examine the nuclear structure.

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Rong Wang, Chengdong Han, Xurong Chen. 2023-09-04. Exploring the Mass Radius of $^4$He and Implications for Nuclear Structure. https://arxiv.org/abs/2309.01416

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