One question I’ve been wondering about for the last 20 years or so has been what SUSY proponents would do when the LHC finally gathered data and found no SUSY. Would they finally admit this was an idea that hadn’t worked out, or would they never give up, no matter what the data said? The answer is now in. John Ellis was a co-organizer of a Royal Society conference earlier this week, and a report from the conference has the following:
“I think that the physics case for supersymmetry has, if anything, improved with the LHC’s first run, in the sense that, for example, supersymmetry predicted that the Higgs [boson particle] should weigh less than 130 gigaelectronvolts, and it does,” Ellis said.
“Of course, we haven’t seen any direct signs of supersymmetric particles, which is disappointing, but it’s not tragic,” Ellis added. “The LHC will shortly almost double its energy — we’re expecting eventually to get maybe a thousand times more collisions than have been recorded so far. So we should wait and see what happens at least with the next run of the LHC.”
And if the LHC’s next run does fail to reveal any sparticles, there is still no reason to give up on looking for them, he said. In that case, new colliders with even higher energies should be built, for collisions at energies as high as 100 TeV.
“I’m not giving up on supersymmetry,” Ellis told LiveScience. “Individual physicists have to make their own choices, but I am not giving up.”
So, Ellis has made his position clear: no giving up, no matter what the LHC data from the next run says.
Is it even theoretically possible that susy will be found at the LHC?
My impression is that the SM is so constrained by high-precision data, that a direct discovery of sparticles at 14TeV is very unlikely. What could rather be found is some anomaly in the high-precision data, which could herald a discovery at yet higher energy. Or something else.
Wow. You’d think ACME’s zero dipole moment measurement for the electron would give the SUSY crowd some cause to doubt that there is an exotic particle zoo out there.
Reasons not to give up on SUSY include the fact that there aren’t many promising alternatives. The two biggest mysteries in physics are dark matter and dark energy, and SUSY can at least hint at solutions. What else can? Nor are there many promising alternatives for quantum gravity.
Physics will move on if something more promising comes up.
It is ironic that the Ptolomaic system failed because it was stuck with the more symmetric circular motion against the less symmetric but observed elliptical motion, while the more symmetric supersymmetry leads to a less symmetric nonspherical electron with a non-observed electric dipole moment. I once had told Edward Witten that supersymmetry can exist without superstring theory but not the other way around. His answer was that you can say this about almost any theory. But without supersymmetry can there be a superstring theory? And how about Juan Maldacena’s anti de Sitter (ADS/CFT) conjecture in face of our more de Sitter (not anti) observed universe? Shall we rally believe in the 10^500 universes? In an e-mail exchange I once had with Lubos Motl, this good man had the following slogan on all of his e-mails: “String/M theory is the language in which God wrote his world”. In a reply I wrote him: “Lubos, this is not science but religion in the guise of science”.
CIP and s.vik.
To give one example : asymptotic safety.
Well, the light Higgs is interesting. I think Ellis has a point there. Of course the confirmation of the precision electroweak analyses is the biggest news. But something or other keeps the Higgs light, and that is definitely interesting. Maybe it is SUSY. Maybe not. Not really Black & White to me that no direct SUSY particles is a complete SUSY rejection. Many searches for free quarks came up empty.
Not just many, but all searches for free quarks came up empty, because there are no free quarks. Any theory of the strong interactions with free quarks is a wrong theory.
Similarly, it’s now pretty clear that superpartners aren’t going to show up, and any theory like the SUSY extensions of the SM that have been studied for 40 years is a wrong theory. Time to look for something quite different if you want to get anything out of SUSY. What’s odd is that Ellis is not talking about that, but about just looking for the same thing at higher energies.
I think you are beeing too simplistic. Notice that among other good things SUSY has gave us is that its also a good “signal generator” in the sense that has trigered interesring searches for physics (and will keep doing so) that may ultimately let to discoveries (sparticles or other physics cases).
Sorry, but I have to admit that thinking of this kind reminds me of a classic feature of conspiracy theories: When evidence arguing against your theory emerges, you simply expand your ‘circle of belief’ to accommodate that evidence.
OK, but here is the obvious question: What group of humans on this planet is going to shell out the billions of dollars needed for a next-generation collider just to look for SUSY?
If the answer is “no one”, what do the SUSY researchers do?
What’s most puzzling is how obvious it is that SUSY is a belief system, and how little that seems to concern its proponents. “SUSY”, in all its myriad permutations, could appear over a vast range of energy scales. “Look at higher energies” is an argument that could hold theoretically no matter how much negative data are produced. It is, after all, exactly what’s been said every time SUSY has lurked just beyond the reach of the current accelerator, yet astonishingly failed to appear. The rationalizations being made today so closely echo those made after the Tevatron shut down, after the LEP shut down…”Well, those expectations were silly, naive, oversold, and clearly the Not-Quite-As-Minimal-As-The-Last-Supersymmetric-Standard-Model tells us the parameter space…” Does it take a genius to get seriously worried about some of these dearly-held beliefs regarding a particular perception of “beauty”? We know what the past has tought us. What can we predict about the future, not only about Nature, but about how human nature impacts our study of Her? From what I can see, this could go on forever. Some even appear to think that’s one of the theory’s key virtues! Is this not all frightening?
“If the answer is “no one”, what do the SUSY researchers do?”
In the absolute worst case scenario, where no evidence ever turns up, one could certainly claim that an LHC in another universe could detect something, and that ripples from this event could be seen in yet another universe, just not ours.
This post is one of the few occasions when the following seems genuinely appropriate: “Never Gonna Give You Up …“
I should say again that I, at least, when I voice my concerns in my own insignificant way, never do so with a sneer. I see these individuals, with very few exceptions, as brilliant, honest, devoted scientists working at the pinnacle of human intellectual achievement. It was their professional ancestors who made “science” what it is. They seem always to be at the forefront of whatever science is evolving into. So the truly worrisome question is, what is science evolving into?
@ CIP. To use “there aren’t many promising alternatives” as an argument for continuing down the susy (string) path seems to be a never-ending loop. If everyone reasons like this an alternative will indeed never be found.
It’s well known that from epistemology that theories do not disappear from one moment to another. They disappear with the scientists who developed them. Then they get old and retire, eventually their theories – which are not supported by data – will retire aswell.
Obviously one can understand psychologically why people like Ellis do not give up. They based decades of their scientific career on this topic. Would you be able to admit that all you have done was wrong? 😮
I think everything goes its predicable way…
Woit, what do you think reasonable scientists in HEP and QG should pursue in the event of no-SUSY in LHC and other experiments? What is a scientifically responsible and reasonable course for HEP/QG after non-SUSY LHC 2016?
Quote:”Obviously one can understand psychologically why people like Ellis do not give up. They based decades of their scientific career on this topic. Would you be able to admit that all you have done was wrong?”
There is a saying I like to use for situations like this: Do you want to be wrong today, or do you want to be wrong forever?
All due credit to anyone who invented it before me.
Oh, God. That’s what I was afraid of.
FUND THE COLLIDER AT ALL COSTS
A new scientific truth does not triumph by convincing its opponents and making them see the light, but rather because its opponents eventually die, and a new generation grows up that is familiar with it
PlanckConstant: a new scientific truth does not triumph by convincing people and making them see the light or by a generation of proponents or opponents dying. It triumphs with experimental evidence.
a bit off topic, but I would like to point out that Ellis’ quote contains a misconception that I think does not belong there, not even if the target of his text are laymen.
I have always believed that in order to explain hard concepts to outsiders
one has to simplify things to the point of making slightly incorrect statements.
But I don’t think that saying “we’re expecting eventually to get maybe a thousand times more collisions than have been recorded so far” falls in that category.
What Ellis forgets is that the rate of event recording is not going to improve by x1000,
but maybe by x2 or x4. CMS and ATLAS have recorded in total less than 10B events, and in the future they won’t go above some tens of billions; that’s because the increase of luminosity is not matched by a multiplication of data acquisition power – and it would not be meaningful of course. A better way to explain what is in store is to say “we are expecting to produce a thousand times more collisions”, retaining the overall meaning.
On a semi-related topic, did you attend this:
and do you think thespeaker’s approach of studying carefully a world with many SUSYs
as toy model can revolutionize our understanding of our world with, perhaps, not even one?
Yes, I was there, will write about this soon. As far as the topic of this posting goes, there was almost nothing in the talk about SUSY, at least in the first two hours…
Fo theorists, the set of reasonable things to work on post no LHC SUSY is about the same as the set of reasonable things to work on pre no LHC SUSY, since there never was a good reason to expect LHC SUSY, and it was a subject that had been studied to death for years.
That’s interesting, I hadn’t thought much about that distinction. I guess it’s not too important if you’re discussing very rare events and some ideal triggering scenario, but clearly there are measurements where the high luminosity is not going to help for the reason you give.
Not just many, but all searches for free quarks came up empty, because there are no free quarks. Any theory of the strong interactions with free quarks is a wrong theory.”
Not quite all, but those that had positive results (Fairbanks, 1980 or so, for example) were (rightfully) discredited. But people kept looking for a long, long time, nice review…
I differ with you, Peter… the issue cannot ever be settled by theory, only by experiment. What we know is that in normal matter the free fractional charge abundance is <10-23 per nucleon or so. I think whether QCD has peculiar and rare states that somehow preserve fractional charge is still an open question, although one that is unpopular.
“Similarly, it’s now pretty clear that superpartners aren’t going to show up, and any theory like the SUSY extensions of the SM that have been studied for 40 years is a wrong theory. Time to look for something quite different if you want to get anything out of SUSY. What’s odd is that Ellis is not talking about that, but about just looking for the same thing at higher energies.''
`Pretty clear' is not the same as doing the experiment and checking. It was `pretty clear' at SPEAR in 1973 that no narrow resonances were present… their scan had skipped over the J/Psi. So in 1974 they found it.
Experimentalists are quite different than theorists. You theorists seem to think you are in a chess match where checkmate means something. Experimentalists find you all a bit ego-driven and narrow, and overly certain (one way, favoring certainty, or another way, rejoicing in rejection).
Experimentalists usually (not always) are much more diffident at heart. I think many experimentalists never caught the SUSY wave but solidly support going to the highest energies technologically possible to look for surprises. Conversely, trash-talking the 14 TeV run because SUSY won't likely be there seems similarly wrong-headed.
You go to the highest energies and look for new phenomena. You keep looking for free fractional charge with whatever clever trick you can find. You look for electric dipole moments, mu-e, dark matter, neutrino mass, etc, etc, and view theorists as an odd opinionated tribe. An odd tribe that was initially quite hostile to, for example, the observation of the tau lepton, to parity violation, to fission… the list is interesting and long.
Well, good luck on getting a machine for higher energies. The well is running dry.
Having studied in the then “world gauge center”, Utrecht University with Veltman and ‘t Hooft, I learned about the standard model but got appalled by SUSY. Seeing its near defeat decades later, does not feel as a victory. Too much damage has been done, first by SUSYers, then by SUGRAvers and the blow by (Super)Stringers. It seems fair to conclude that physics reached the end of the Gauge Principle. How to continue? Why not look at the basis of quantum mechanics? Its measurement problem has been solved recently, leading towards its statistical or ensemble interpretation akin to classical ensemble theory, doing away with many worlds, many minds and so on. But if we do one experiment and get one outcome, one may ask the question: what goes on in the apparatus to generate this outcome? We do not have a theory for this down-to-earth question! So my bets are on a sub-quantum theory, more classical than quantum theory itself. Integration with gravity should be done at that level. Not surprisingly, the possibility of a sub-quantum theory kept Einstein and ‘t Hooft busy for decades.
This answer the what-to-do question: Turn around and start again.
You write that the measurement problem in quantum mechanics has been solved recently …
This is a very important statement. Please give the relevant references. Thanks.
There is something I find a bit incredible. In the past, 1. the theorists were making predictions, 2. if the predictions were correct, the theorist received recognition, 3. if they were not verified, the theorists were not recognized. Now, it seems that none of these considerations matter.
E.g., nobody asks a SUSY theorist to make predictions, only moral suasion; if the predictions are wrong, the theorist can simply change them; finally, the recognition is for granted, once the theorist is paid by a prestigious place and if he/she can publish empty but successful papers.
Instead, when I hear a talk of a theorist, I immediately ask: What are his/her achievements in physics? This simplifies a lot the assessment and allow me to save a lot of time.
I strongly disagree with your conclusion that the failures of SUSY/SUGRA/Superstring theory mean the “end of the gauge principle”. A better conclusion would be that they indicate something went awry in the “SUSY” extension, not with gauge symmetry (where the recent discovery of the Higgs vindicates the gauge theory point of view).
Sorry, but measurement theory in QM, while a wonderful topic, is off-topic here.
I don’t really disagree with you. By all means, experimentalists should do whatever they can to look for new phenomena. To the extent though that they have to make choices and decide to get some guidance from theory, best to work with a clear-eyed view about what theory does say and what it doesn’t. By all means, look for fractionally-charged objects, but realize that the ones theorists saw as most likely in 1964 (u,d,s quarks) now look quite unlikely, so better to search widely and not assume anything about, for instance, which fractional charges to look for. Similarly, of course the higher energy LHC run is important and searches should be done there for anything and everything that might show up. When designing triggers, etc., though, it would be a good idea to make sure things are not narrowly tuned to looking for specific superpartners heavily advertised in the past by theorists, since such theories now look quite unconvincing.
GoletaBeach makes an interesting point. Scientific American has a cover story this month about how two valid methods of measuring the radius of the proton give two very different answers. The CERN briefing book says that the spin of the proton can’t come close to being derived from the measured spins of its component parts. Transverse polarized proton beam collisions either violate the QCD prediction massively or nobody knows how to compute the correct prediction. Are protons too “composite” to interest high-energy theorists these days? It’s hard for a layman to understand the apparent lack of interest in such fundamental matters (no play on words intended). I’m very fond of the protons that give me most of my mass while kindly refraining from decay, even if it turns out that their components have no superpartners.
We’re on the same wavelength, Peter. Leptons and missing energy and jets remain the fundamental things to look at, and will always be done. What is really hard to guarantee is that there won’t be another `scanned over the J/psi’ , that is, missing something by not considering all the possibilities type of oversight in the 14 TeV.
srp, oddly enough, the size of the proton is not considered by most particle physicists as particularly sensitive to interesting new physics. We could be wrong, in fact, I hope we are wrong. My guess is that the two different measurement techniques (electron scattering and muon atoms) might have slightly different corrections needed to back out the fundamental thing, that is the size of the proton. And maybe nobody has spent sufficient time doing those corrections accurately to the few in a 100 level.