# How do the right-handed fermions acquire mass?

I am constructing a presentation on how elementary particles acquire mass via interaction with Higgs field. I asked this question previously in a different form and received the usual clap trap, so I researched it personally. I have most everything else ready but the following.

What I need to know specifically right now, is how do the right handed elementary fermions acquire mass? or don't they? I am familiar with the process for the left handed fermions re absorption and emission of the weak hypercharge.

No maths please plain English if anyone is willing to respond. Pls don't send me to text books or other websites.

• Perhaps this is related to ESB ( electroweak symmetry breaking), and these masses are generated by the Higgs vacuum expectation value and goes to new pathways for physics beyond the Standard Model.see for discussion:quantumdiaries.org/2011/06/19/… – drvrm Jul 14 '16 at 6:59

Charged fermions get masses through their cubic "Yukawa" interactions with the Higgs $$L_{Yuk} = y\cdot h \psi_L \psi_R$$ When the Higgs field is $h=v$ in the vacuum, the simple part of this cubic term generates the quadratic term $$m \cdot \psi_L \psi_R$$ which is the mass term for the fermion, $m=yh$. Note that the mass term is something that depends both on the left-handed field and the right-handed field. Charged particles' masses cannot be chosen separately for the left-handed and right-handed parts. The Dirac mass is something that allows the left-handed chiral fermion to turn into the right-handed one and vice versa. (The angular momentum is preserved in these processes but the helicity is not.)
The situation is different for neutrinos, the neutral fermions we know. In that case, there may still be masses of the Dirac type I just mentioned. But there may also be Majorana mass terms proportional to $\psi_L \psi_L$ that violate the lepton number by $\Delta L = \pm 2$. For the visible left-handed neutrinos, these terms cannot appear at the tree level. But they may be generated as an effective interaction from some high-scale physics. The high-scale physics may also contain Majorana mass terms with a very heavy mass for the right-handed neutrinos, $M\psi_R \psi_R$. The coefficient $M$ here may be high, e.g. at the GUT scale. This mass term doesn't contradict any known conservation laws because $\psi_R$ is a Standard Model singlet (carries no conserved charges or representations).