# 13.1. Introduction to Nucleosynthesis¶

Yonglin is working on the impact of neutrinos on nucleosyntheis, especially on r-process in Neutron Ster Merger(for a good review, check Neutron Star Mergers and Nucleosynthesis of Heavy Elements)

Why are we interested in r-process?

Because it is very important.

WHY

AAAAAAAAAA

## 13.1.1. XXXXXX¶

Projection Technique :class: note

First of all define a diagonalizing operator \(\hat D\) which just keeps the diagonal elements and simply drops the off diagonal elements. We see that \(1-\hat D\) will eliminate all diagonal elements.

We can define the diagonalized density matrix as \(\hat \rho_d = \hat D \hat \rho\) and off-diagonalized density matrix as \(\hat \rho_{od} = (1-\hat D)\hat \rho\). As an application,

\[\hat \rho = \hat \rho_d + \hat \rho_{od} .\]

What to Do?

wait