The atomic nucleus as a bound system of $3A$ quarks

TL;DR

This paper explores modeling the atomic nucleus as a bound system of quarks using effective theories, gauge/gravity duality, and modified bag models to explain nuclear properties and stability.

Contribution

It introduces a modified bag model combined with gauge/gravity duality to describe nuclear static properties and predict limits of nuclear stability.

Findings

The model explains the approximate equality of u and d quarks in light nuclei.

It predicts the maximum charge of stable heavy nuclei as Z≈82.

The framework accounts for the finite number of stable elements in the periodic table.

Abstract

The atomic nucleus, viewed as a system of bound quarks, should, in principle, be described within an effective theory of low-energy quantum chromodynamics. This paper provides an overview of recently developed models that embody essential features of the desired effective theory. The Fermi gas model helps explain why the number of $d$ quarks is approximately equal to that of $u$ quarks in stable light nuclei up to ${\rm {}^{40}_{20}Ca}$. A modified bag model accounts for the deviation from this rule in heavier nuclei. With this model, the static properties of a wide range of stable nuclei can be described with reasonable accuracy. To make the most of the modified bag model, it is useful to invoke gauge/gravity duality. A refined version of duality states: ``The dynamics inside an extremal black hole in ${\rm AdS}_5$ is mapped onto the corresponding dynamics of a stable subnuclear system in ${\mathbb R}_{1,3}$''. This version of duality allows one to predict the primary decay channel of the lightest glueball. Another implication is that this framework explains why the periodic table contains a finite number of stable elements. Duality makes it possible to calculate the maximum allowed charge $Z_{\rm max}$ of stable heavy nuclei: $Z_{\rm max}\approx 82$, which is the charge of the ${\rm {}^{208}_{82}Pb}$ nucleus.