The 1932 Majorana Equation: A Forgotten but Surprisingly Modern Particle Theory

Round 1

Reviewer 1 Report

In this paper, the author reviews the Majorana equation that is proposed in 1932. Then it is shown that infinite components of state appears as a solution whose masses are given by quantum number. I think it is worth to revisit the equation giving some insight. So the paper can be published after the author answering questions below.

1. At line 189 below Eq.(17) it is said $T^\dagger T = \beta$ while $\beta = T^2$ is written below Eq.(18). It is nice to add a comment to explain.

2. Below Eq.(32) $x$ and $y$ should be $x_0$ and $y_0$ in the definition of $\lambda_0$?

3. Below Eq.(42) charged lepton mass is discussed. I wonder if there is n=3 state. In there is such case a particle heavier than tau lepton appears that might not be realistic. It is nice to add some comments regarding this point.

4.$m_\mu$ at the third equation of Eq.(49) should be $m_\tau$.

Author Response

See attached file.

Author Response File: Author Response.pdf

Reviewer 2 Report

In this manuscript the author revisits the Majorana equation on relativistic particles with arbitrary intrinsic angular momentum. In particular time-like, space-like and light-like solutions of the equation are discussed for free particles. Last part is dedicated to some speculative interpretation of the mass term (which was not commented by Majorana), correlating the mass values of the charged leptons, and extending the formalism to baryons and  mesons, making contact with suggested mass formulas in the literature.
While I am skeptical about the robustness and usefulness
of this last part (section 4), the previous sections are interesting, certainly from the point of view of history of physics.

The manuscript is well written.   
Overall, I think  the manuscript can be published.

Author Response

See attached file.

Author Response File: Author Response.pdf

Reviewer 3 Report

See attached pdf.

Comments for author File: Comments.pdf

See attached pdf.

Author Response

See attached file.

Author Response File: Author Response.pdf

Round 2

Reviewer 3 Report

In line 51, 

"it can explains"

must be corrected to

"it can explain"

In line 51, 

"it can explains"

must be corrected to

"it can explain"

Author Response

The grammar error highlighted by the reviewer has been corrected. Before submission, the paper was edited by an English professional service. The error probably comes from the conversion in the MPDI template.
I thank the reviewer for the deep attention paid to reading the manuscript.