# 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