I’ve been thinking about what to write about this essay by Ben Allanach, which gives his take on the current state of HEP theory. Allanach is a specialist on the phenomenology of SUSY models, but here he announces that he’s basically giving up on these models:
The trouble is that it’s not clear when to give up on supersymmetry. True, as more data arrives from the LHC with no sign of superpartners, the heavier they would have to be if they existed, and the less they solve the problem. But there’s no obvious point at which one says ‘ah well, that’s it – now supersymmetry is dead’. Everyone has their own biased point in time at which they stop believing, at least enough to stop working on it. The LHC is still going and there’s still plenty of effort going into the search for superpartners, but many of my colleagues have moved on to new research topics. For the first 20 years of my scientific career, I cut my teeth on figuring out ways to detect the presence of superpartners in LHC data. Now I’ve all but dropped it as a research topic.
While most HEP physicists still try and end their talks with some sort of optimistic expression of hope that things will change soon, I was struck by a recent talk by John Iliopoulos, which was more somber and more realistic:
No coherent picture emerges
We were expecting new physics to be around the corner…..
But we see no corner
The easy answer: We need more data
Two problems: (i) We do not know what kind of data
(ii) They will not come for quite a long time
A rather frustrating problem!
and he ends with
The Future of Particle Physics will undoubtedly be bright, but
I will not learn the answer
While thinking about this I happened to look at an old posting of mine, a review of Lisa Randall’s Knocking on Heaven’s Door written back in 2011. There I wrote
One odd thing about the book is the title, which for Randall carries a positive meaning that she acknowledges doesn’t correspond to the very dark one of the Bob Dylan song from the soundtrack of the Sam Peckinpah film. It’s a beautiful song, but one not about finding truth, but about getting shot in the gut and facing death, hopefully not relevant to particle physics in the LHC era:
Mama, put my guns in the ground
I can’t shoot them anymore.
That long black cloud is comin’ down
I feel like I’m knockin’ on heaven’s door.
It does seem like much of the last 40 years of HEP theory is now “knockin’ on heaven’s door”, deeply wounded by negative results from the LHC. What this means for the future is still up in the air: what story about what has happened will become the conventional wisdom?