# Majorana Equation Explained for Newbies

• WeakCarrier
In summary, the conversation discusses the realistic wave equation, also known as the Dirac equation, which describes a spin-1/2 particle with a 4-component wave function. The equation is derived using Dirac matrices and states that E^2-p^2=m^2. The conversation also mentions the Majorana spinor, which is equal to its antiparticle and is explained in Peskin and Schroeder's exercise 3.13. This spinor is postulated to explain neutrino physics.

#### WeakCarrier

can someone please explain this realistic wave equation
i'm new with spinors :)

Last edited by a moderator:
I think you mean "relativistic wave equation" also called the "Dirac equation". the slashed $$\partial$$ is Feynman's short form for $$\gamma^\mu\partial_\mu$$ where $$\gamma^\mu$$'s are the Dirac matrices (4x4) and $$\mu=0,1,2,3$$. In essence, it is just an equation saying that $$E^2-p^2=m^2$$ for a spin-1/2 particle with wave function $$\psi$$. $$\psi$$ is a 4-component object.
I guess I can go on and derive everything but since I don't know what level you are at, I shall keep my explanation to that as this stage. feel free to ask again.

The wikipedia article where you got the image from explains that this is a similar equation to the Dirac equation, but, however, with the difference that it contains the spinor and its conjugate in the same equation (there are two separate Dirac equations for the spinor and its congujate). This is due to the fact that the Majorana spinor has its particle equal to its antiparticle, $\psi = \mathcal{C}\psi\mathcal{C}^{-1}$ with $\mathcal{C}$ charge conjugation. This condition implies $\psi = - i \gamma^2 \psi^{\ast}$ as you can verify in Peskin and Schroeder eq. (3.145) ($\gamma^2$ the second gamma matrix and $\psi^{\ast}$ the complex conjugate). This is sometimes called Majorana condition. The properties of this spinors as well as the Lagrangian that lead to that equation are explained in exercise 3.13 of Peskin and Schroeder. Majorana spinors are postulated to explain neutrino physics.

Last edited:

## 1. What is the Majorana equation?

The Majorana equation is a mathematical equation that describes the behavior of spin-half particles, such as electrons or protons. It was proposed by Italian physicist Ettore Majorana in the 1930s.

## 2. What does the Majorana equation explain?

The Majorana equation explains the behavior of spin-half particles in quantum mechanics, particularly in relation to their mass and charge. It also has implications for understanding the nature of dark matter and the origin of matter in the universe.

## 3. How does the Majorana equation differ from other quantum equations?

The Majorana equation differs from other quantum equations, such as the Schrödinger equation or the Dirac equation, in that it describes particles with no charge. It also predicts the existence of a unique type of particle called the Majorana fermion, which is its own antiparticle.

## 4. What are some real-world applications of the Majorana equation?

One potential application of the Majorana equation is in the development of quantum computers. The Majorana fermion, with its unique properties, could be used as a qubit (quantum bit) in quantum computing systems, which have the potential to perform certain calculations much faster than classical computers.

## 5. Is the Majorana equation a proven concept?

While the Majorana equation has been extensively studied and has shown promising results in theoretical models, its existence has not yet been definitively proven through experiments. However, recent advancements in technology have allowed for the potential detection of Majorana fermions, bringing us closer to confirming the validity of the Majorana equation.