The eV scale IV

Unless I have forgotten something, I do not know a good explanation for where a new, 1 eV scale of physics (e.g. as the mass of a sterile neutrino) would come from. Sheppeard has an idea but it relies on a particular mass spectrum for the active neutrinos, that I don't find compelling.

Reality of a 1 eV neutrino seems to require baroque interactions. They would also be needed to satisfy cosmological constraints (section 3).

Dual purpose Higgs

Someone at a philosophy club asked me about the Higgs boson, and I was saying the usual stuff about how it's the Higgs field which does the real work, and 'the Higgs boson' is actually just a leftover, the only one of four Higgs field excitations which doesn't even get absorbed into a gauge boson... but the Higgs mass does turn out to be important and mysterious since it indicates our vacuum is critically tuned by unknown means and for unknown reasons. Oh, and there's also a theory that the Higgs is the inflaton.

Afterwards I was thinking, isn't it strange that the leftover Higgs boson should happen to be the messenger of criticality? Is there some theoretical framework, in which this neat division of labor between seemingly disparate tasks - electroweak goldstones, and messenger of criticality - makes sense, is to be expected, is the product of a deeper unity? That's the question for today.

Some intuition makes me think of conformal symmetry breaking. As if the Higgs is a top condensate that spontaneously breaks conformal symmetry and electroweak symmetry at the same time, and the mechanics of the process is responsible for giving it a critically tuned mass. But I do not know a mechanism that works this way.

Desert denial

There is lately a debate about whether a new generation of even more powerful particle accelerators would be scientifically warranted. I have said a few times that the LHC's most important discovery may be, not just confirmation of the Higgs boson's existence, but determination of its mass as being around 125 GeV, because that places the standard model vacuum on the edge of instability.

Light scalars have a finetuning problem, and the theoretical expectation was that there are other particles (such as superpartners) that render physics "natural" through quantum cancellations. The failure of such particles to appear, along with the discovery that the Higgs mass is tuned to a critical value, might lead one to suppose that whatever mechanism is responsible for this critical tuning, is also responsible for stabilizing it.

As it happens, the Higgs mass was more or less predicted by Shaposhnikov and Wetterich in 2009, using an alternative quantum gravity paradigm. Even given the attractions of string theory, I always thought their work was mysteriously neglected. But now it occurs to me: maybe it's because their theory is premised on a 'desert' - no new particles to discover at higher energies - so it has no instrumental value when making the case for new colliders.