Blog – Of Particular Significance

It has been a somber weekend in New York. In a city of many millions, thousands of premature deaths in ninety minutes  left a deep scar.  Among my acquaintances, not everyone knew someone who died, but it seems almost everyone knew someone who knew someone who perished.  And for those of us who watched the towers being built, wandered for years in their shadows, and walked on the roof deck gaping at the astounding view, their destruction and absence from the skyline will be permanently unsettling, and motivating.  I have stood atop that which does not exist; my memory floats in the air.

Three nights ago I was far downtown, and the austere memorial that has graced Manhattan skies each September — a pair of vertical shafts of blue-white floodlight, recalling the towers — was illuminating the sky just overhead.  Several layers of thin clouds caught the light, creating pairs of soft-edged moons stacked one atop the next.  As the wind rushed the clouds along, each moon separately glowed and flickered, yielding a spectacle at once simple and enigmatic — a conjunction of artifice and nature, of the steady and the unpredictable.

There’s much to say about the aftermath of 9/11/01 and the consequences, as far as internal and external U.S. politics, U.S. society and values, and U.S. science in particular. But not right now.

In the next week (two weeks? three?), in between pushing two papers toward completion and preparing a colloquium (= a talk intended for an entire physics department) that I will give a few times this year, I will try to use my last week’s intensive study of the existing papers and talks from the Large Hadron Collider (LHC) to characterize what their measurements tell us so far about nature — and what they don’t tell us.  This isn’t easy, at the very least because [for very general reasons] one typically can’t rule out a class of theories (such as supersymmetry or extra dimensions or technicolor) through a single set of measurements — and conversely, a single measurement says something about many classes of theories.   Given this, should a discussion of LHC results be organized by measurements or by theories?  By empirical data from nature or by the  ideas of the human mind?  These practical questions have a principled side, and the answers illuminate more than we might initially expect.  For what is the best way to summarize our knowledge so that we actually know what we know?

I have updated the article laying out some of the implications of the search for the Higgs particle, as of September 2011.  In particular, I filled in the last two subjects in the table of contents:

1. The Standard Model Higgs particle
2. A Standard Model Higgs sector but with Other New Particles
3. The case of two Higgs particles
4. The case of five Higgs particles
5. Supersymmetry: Five Higgs particles along with superpartners [new!]
   
6. No Higgs particle (to speak of) [new!]
   

If you’d like to learn a bit about how Higgs particles work in supersymmetric theories, and about how a theory can have a Higgs field but no Higgs particle, you may enjoy taking a look at the new material.  Implications of the Higgs searches so far are still rather limited for these two cases, but the article describes what you should keep an eye on, and why.

Two full non-stop days of work at Canada’s Perimeter Institute, filled with  intensive study of the papers, notes and conference talks from the ATLAS and CMS experiments at the Large Hadron Collider, have left me slightly exhausted but pretty well up-to-date.   This higher level of knowledge will start to percolate into these pages almost immediately.

Meanwhile, a bit more insight into the CRESST dark matter situation (see yesterday’s post). There  have already been silly press articles.  The BBC article says

• Researchers at the Cresst experiment in Italy say they have spotted 67 events in their detectors that may be caused by dark matter particles called Wimps.

No, that’s not what they said.  (more…)

Well, just as if we didn’t have enough to keep track of in particle physics, along comes another claim that dark matter has been detected, by looking for extremely rare and faint signals of collisions of dark matter particles with atomic nuclei in a special type of crystal. (more…)

Working hard at Canada’s Perimeter Institute, that is.   Longer posts are on hold for a couple of days while some friends and I stuff our brains with the details of as many ATLAS and CMS papers as we can handle.  We’ve gotten through fifteen or so, I suppose, on several topics.  Already I have learned a lot about the Higgs searches and the supersymmetry-like searches, which eventually will make their way onto these pages.   There are many devils in the details…  In the meantime, in case you’re interested, I did a small update to the article on the  implications of current data for Higgs particles of various types.

I’ve started a new article [click here] that tries to lay out the scientific implications of the Large Hadron Collider searches for the Higgs particle, as of early September 2011.   It’s a work in progress, so there will be more to come.  So far I’ve considered the implications for the Standard Model itself [recall the Standard Model consists of the known elementary particles and the simplest possible Higgs field and particle], and for variations on the Standard Model in which nature has a few extra types of particles that we don’t know about yet.  I’ll get to more complex cases, including supersymmetry and its five Higgs particles, later.  But I’ll bet that you will already be shocked at how different is the case of the Standard Model itself, which is easy to discuss succinctly, from even the simplest variants of the Standard Model.