As you can see elsewhere on these pages, I am intrigued by the possibility that the particles and symmetry of the Standard Model may be “emergent” – arising from an underlying theory without these fields or symmetries. While I would also like to find a viable theory with this property, it is also important to think of ways to test this possibility. As explained in a talk that I gave at the Meeting on CPT and Lorentz Symmetry, this can happen if we observe a violation of gauge invariance or of general covariance.
Mohamed Anber, Ufuk Aydemir and I are involved in a set of projects that develops this idea. The paper describing this program has been posted on the arXiv. Space limitations prevent full comments and also full referencing, but hopefully we can provide these in our future papers.
This idea is pretty unconventional in particle physics. However, that is an attraction. Thinking about this new topic leads to many interesting ideas and who knows where it will lead!

This week Thibault Damour and I put out two papers on potential violations of the equivalence principle due to light scalars. These are:

a short paper with the main results designed to be easier to read, and

a longer paper with more detail and discussion of several theoretical issues

I think that these will be useful for the field. Maybe the most unusual aspect is that they took 7.5 years to complete. On my sabbatical to the IHES, Thibault was discussing the EP and noted that the main unknown was in the effects of nuclear binding. This lead to my work on the quark mass dependence of nuclear binding, and our other collaborative work on limits on the variation of quark masses. So it has been a fruitful effort, but it sure did take longer than it needed to.