Skip to main content

Dear Dr B: Why Are Neutrinos Prove For Physics Beyond The Criterion Model?

Dear Chris,

The criterion model of particle physics contains 2 dissimilar types of particles. There are the fermions, which brand upwardly matter, in addition to the gauge-bosons which mediate interactions betwixt the fermions and, inwards approximately cases, amid themselves. There is i additional particle – the Higgs-boson – which is needed to give masses to both bosons in addition to fermions.

Neutrino number at the IceCube Observatory inwards Antarctica.
Image: IceCube Collaboration

The fermions come upwardly inwards left-handed in addition to right-handed versions which are mirror-images of each other. In what I recollect is the most perplexing characteristic of the criterion model, the left-handed in addition to right-handed versions of fermions comport differently. We state the fermions are “chiral.” The departure betwixt the left- in addition to right-handed particles is most apparent if yous hold off at neutrinos: Nobody has always seen a right-handed neutrino.

You could say, well, no problem, let’s simply become rid of the right-handed neutrinos. Who needs those anyway?

But it’s non that slow because nosotros accept known for xx years or in addition to so that neutrinos accept masses. We know this because nosotros encounter them mix or “oscillate” into each other, in addition to such an oscillation requires a non-vanishing mass-difference. This agency non all the neutrino-masses tin last zero.

Neutrino masses are a complication because the commons way to give masses to fermions is to span the left-handed version alongside the right-handed version in addition to alongside the Higgs. So what practice yous practice if yous accept no right-handed neutrinos in addition to yet neutrinos are massive?

The electrical flow condition is thence that either a) in that place are right-handed neutrinos but nosotros haven’t yet seen them, or b) neutrinos are dissimilar from the other fermions in addition to tin become masses inwards a dissimilar way. In either case, the criterion model is incomplete.

It is partly an number of terminology though. Some physicists state right-handed neutrinos are business office of the criterion model. In this instance they aren’t “beyond the criterion model” but instead their regain is pending.

I accept a personal fascination alongside neutrinos because I believe they’ll last fundamental to agreement the designing of particle-masses. This is because the right-handed neutrino is the solely particle inwards the criterion model that doesn’t send gauge-charges (or they are all zero, respectively). It seems to me that this should last the argue for it either beingness really heavy or non beingness in that place at all. But that’s speculation.

In whatsoever case, in that place many neutrino experiments shortly nether way to closer written report neutrino-oscillations in addition to equally good to hold off for “neutrinoless double-beta decay.” The relevance of the latter is that such a decay is possible solely if neutrinos are dissimilar from the other fermions of the criterion model, in addition to so that no additional particles are needed to practice neutrino masses.

So, no, particle physics isn’t dead in addition to over, it’s withal amount alongside discoveries waiting to happen!

Thanks for an interesting question.

See also:
or click here for all posts inwards this series.
Labels:

Comments

Post a Comment

Popular posts from this blog

Outraged Nigh The Google Multifariousness Memo? One Desire You Lot To Mean Value Nigh It.

Chairs. [ Image: Verco ] That leaked internal memo from James Damore at Google ? The 1 that says 1 shouldn’t hold off employees inwards all professions to reverberate the demographics of the whole population? Well, that was a pretty dumb affair to write. But non because it’s wrong. Dumb is that Damore thought he could receive got a reasoned give-and-take close this. In the USA, out of all places. The version of Damore’s memo that get-go appeared on Gizmodo missed references together with images. But meanwhile, the multifariousness memo has its ain website together with it comes with links together with graphics. Damore’s strikes me equally a pamphlet produced past times a well-meaning, but also utterly clueless, immature white man. He didn’t deserve to get fired for this. He deserved mayhap a slap on the too-quickly typing fingers. But inwards his world, bespeak for give-and-take is evidently plenty to learn fired. I don’t commonly write close the underrepresentation of wo...
Post a Comment
Read more

Away Note

I’ll endure inwards Utrecht adjacent calendar week for the 19th U.K. together with European Conference on Foundations of Physics . August 28th I’ll endure inwards Santa Fe, September sixth inwards Oslo , September 22nd I’ll endure inwards London for about other installment of the HowTheLightGetsIn Festival . I convey been educated that this festival derives its advert from Leonard Cohen’s vocal “Anthem” which features the lines “Ring the bells that withal tin ring Forget your perfect offering There is a fissure inwards everything That’s how the calorie-free gets in.” If you lot convey read my book , the fissure metaphor may telephone a bell. If you lot haven’t, you lot should. Oct third I’m inwards NYC, Oct fourth I’m inwards Richmond, Kentucky, together with the instant calendar week of Oct I am at the International Book Fair inwards Frankfurt. In instance our paths cross, delight tell “Hi” – I’m e'er happy to come across readers irl.
Post a Comment
Read more

Dear Dr B: Should 1 Report String Theory?

Strings. [image: freeimages.com ] “Greetings doctor Hossenfelder! I am a Princeton physics major who regularly reads your wonderful blog. I lately came across a curious passage inwards Brian Greene’s introduction to a reprint edition of Einstein's Meaning of Relativity which claims that: “Superstring theory successfully merges full general relativity in addition to quantum mechanics [...] Moreover, non exclusively does superstring theory merge full general relativity with quantum mechanics, but it also has the capacity to comprehend — on an equal reason — the electromagnetic force, the weak force, in addition to the strong force. Within superstring theory, each of these forces is merely associated with a dissimilar vibrational designing of a string. And so, similar a guitar chord composed of 4 dissimilar notes, the 4 forces of nature are united inside the music of superstring theory. What’s more, the same goes for all of thing every bit well. The electron, the quarks,...
Post a Comment
Read more