# Heavy hadron molecules in effective field theory: the emergence of exotic nuclear landscapes

## TL;DR

This paper demonstrates that heavy hadron molecules can be described by effective field theories identical to those of nuclear physics, leading to the conjecture of exotic nuclear landscapes composed of heavy hadron bound states.

## Contribution

It establishes a formal equivalence between nuclear and heavy hadron effective field theories and explores their implications for exotic nuclear structures.

## Key findings

- Heavy hadron interactions can be expressed in terms of light quark degrees of freedom.
- The analogy allows calculation of two-pion exchange diagrams in heavy hadron systems.
- Proposes the existence of exotic nuclear landscapes with heavy hadron bound states.

## Abstract

Heavy hadron molecules were first theorized from a crude analogy with the deuteron and the nuclear forces binding it, a conjecture which was proven to be on the right track after the discovery of the $X(3872)$. However, this analogy with nuclear physics has not been seriously exploited beyond a few calculations in the two- and three-body sectors, leaving a great number of possible theoretical consequences unexplored. Here we show that nuclear and heavy hadron effective field theories are formally identical: using a suitable notation, there is no formal difference between these two effective field theories. For this, instead of using the standard heavy superfield notation, we have written the heavy hadron interactions directly in terms of the light quark degrees of freedom. We give a few examples of how to exploit this analogy, e.g. the calculation of the two-pion exchange diagrams. Yet the most relevant application of the present idea is the conjecture of exotic nuclear landscapes, i.e. the possibility of few heavy hadron bound states with characteristics similar to those of the standard nuclei.