Monday, February 20, 2017

Will SMASH Be A Smash?

Here comes a new extension to the Standard Model!

A new theoretical paper in PRL has extended the Standard Model of elementary particles to include new particles, and tries to mash different ideas and theories into this new standard model called SMASH - Standard Model Axion See-saw Higgs portal inflation (yeah, it's a mouthful).

SMASH adds six new particles to the seventeen fundamental particles of the standard model. The particles are three heavy right-handed neutrinos, a color triplet fermion, a particle called rho that both gives mass to the right-handed neutrinos and drives cosmic inflation together with the Higgs boson, and an axion, which is a promising dark matter candidate. With these six particles, SMASH does five things: produces the matter–antimatter imbalance in the Universe; creates the mysterious tiny masses of the known left-handed neutrinos; explains an unusual symmetry of the strong interaction that binds quarks in nuclei; accounts for the origin of dark matter; and explains inflation.

Of course, with ANY theoretical ideas, which often has long gestation period, a lot of patient waiting and testing will have to be done to verify many of its predictions. But this seems to create quite an excitement in revamping the Standard Model.



Douglas Natelson said...

Dumb question: Given that ordinary, garden-variety neutrinos are massive, doesn't that mean that they can't be helicity eigenstates, so that it should be possible to find a right-handed electron neutrino, for example? I mean, in principle if you find an ordinary left-handed relativistic electron neutrino, it should be possible to boost into a frame moving in the same direction and just a hair faster than the neutrino, and to an observer in that frame the neutrino would look right-handed. (That must mean that when these folks say "right-handed neutrinos" they mean that you'd have to do that procedure to make those particles look left-handed. Still, if all inertial frames are equivalent, then handedness just doesn't seem meaningful here.)

ZapperZ said...

I know that the spin property may change under a Lorentz boost. See, for example:

Hui Li and Jiangfeng Du, Phys. Rev. A 68, 022108 (2003).

So they must obviously have a "proper" frame for this to be unambiguous.