What Are the Key Differences Between Dirac and Majorana Masses?

[Trixie Mattel]

Hello,

I am having a real problem trying to figure out what a Majorana mass is.

The only thing I gather so far is that dirac mass is the mass that is the result of the Higgs Mechanism.

What exactly is the Majorana mass, and for which particles does it exist.Thank you

 

[vanhees71]

Have a look at the following lecture notes. There's a nice explanation of what Majorana fermions are:

https://www.nikhef.nl/pub/theory/academiclectures/QFT2012-Majorana.pdf

In the Standard Model of elementary particle physics all fermions are treated as Dirac fermions. Since only uncharged fermions can be Majorana fermions, because otherwise you'd violate charge conservation (which is bad since if you violate charge conservation you also violate gauge invariance which is at the heart of the standard model), the only candidates of the particles in the standard model for being Majorana fermions are the neutrinos, and it's up to now not clear whether they are Dirac fermions as assumed in the Standard Model or Majorana fermions, i.e., their own antiparticles. To clarify this question one looks for neutrino-less double beta decay:

https://en.wikipedia.org/wiki/Double_beta_decay

 

[Trixie Mattel]

Have a look at the following lecture notes. There's a nice explanation of what Majorana fermions are:

https://www.nikhef.nl/pub/theory/academiclectures/QFT2012-Majorana.pdf

In the Standard Model of elementary particle physics all fermions are treated as Dirac fermions. Since only uncharged fermions can be Majorana fermions, because otherwise you'd violate charge conservation (which is bad since if you violate charge conservation you also violate gauge invariance which is at the heart of the standard model), the only candidates of the particles in the standard model for being Majorana fermions are the neutrinos, and it's up to now not clear whether they are Dirac fermions as assumed in the Standard Model or Majorana fermions, i.e., their own antiparticles. To clarify this question one looks for neutrino-less double beta decay:

https://en.wikipedia.org/wiki/Double_beta_decay

Thank you. So, a Majorana mass term can only be given to a majorana particle, and the only particle that that could possibly be is the neutrino??
But what is the difference really between majorana mass and a dirac mass? Also can majorana particles have both dirac and majorana terms?