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String theorists betting against SUSY July 23, 2008

Posted by dorigo in physics, science.
Tags: , ,

This post contains second-hand information, but I place it here anyways because a blog is also a record of things. So, I read with interest on Peter Woit’s blog a summary of the latest paper posted on the ArXiv by Bert Schellekens. Peter’s review is worth reading head to tail (I don’t know about the 80-something page long article), but I especially found interesting a quote from Schellekens’ paper, which says it as clear as one can make it:

With the start of the LHC just months away (at least, I hope so), this is more or less the last moment to make a prediction. Will low energy supersymmetry be found or not? I am convinced that without the strange coincidence of the gauge coupling convergence, many people (including myself) would bet against it. It just seems to have been hiding itself too well, and it creates the need for new fine-tunings that are not even anthropic (and hence more serious than the one supersymmetry is supposed to solve).

Be sure to get this right: he is a die-hard landscape-enthusiast string theorist. And he is saying he would bet against SUSY at the LHC.

With the CERN machine’s start just around the corner, things are indeed getting to some accumulation point -I myself, after having bet heavily (well, for my standards) against the observation of SUSY at LHC, am starting to think I might in the end turn out the happy loser.

What is worth mentioning and is my final prediction, however, is that as soon as protons will start hitting other protons in the head at 10 TeV this fall, we will slowly relax and realize it’s going to take a while before we can say anything from that mess of hadrons that is going to come out of the center of CMS and ATLAS every 25 nanoseconds.



1. bozox - July 23, 2008

Let me make another LHC prediction: there will be no physics this year. 😦

2. Alejandro Rivero - July 24, 2008

Yes it is funny as opinions move… I’d like to think that it is in function of new evidence.
On my side, I have filed to go to the Strings2008 conference!

3. Kea - July 24, 2008

You mean you have applied? Anyway, have fun.

4. Luboš Motl - July 24, 2008

Well, there are surely more famous string theorists than Schellekens who also think that there’s no low-energy supersymmetry. It’s simply an open question.

String theory allows vacua where it’s broken anywhere between low energies and the Planck scale, and some potentially realistic vacua, unrelated to the superstring, don’t have to have SUSY even at the Planck scale.

Should everyone have the same opinion about a question that is obviously open? Is this how you imagine that physics should work?

I think that the arguments for SUSY are inherently stronger and SUSY more likely does exist at a few TeV than not but I clearly have no full satisfactory proof.

5. craig1 - July 24, 2008

Wow. Very interesting !

6. Andrew Jaffe - July 25, 2008

Er, maybe I’m misunderstanding, but I think you’ve got Schellekens’ point wrong: the important clause is “without the strange coincidence of the gauge coupling convergence” — which sort of occurs in the standard model, but is much better with SUSY.

7. Alejandro Rivero - July 25, 2008

Indeed it is an important point. It is the only argument to think about GUT and Planck scales having a role in HEP physics. Were it a red herring, most of the research on susy and strings would appear to be misguided. But if it is, and the “real action” happens -as I believe- in the electroweak scale, then why do these couplings meet? Coincidence? Some residual symmetry? emergence of gravity?

8. Rumors on SUSY « The Gauge Connection - July 25, 2008

[…] there has been some rumors in the blogsphere about string theorists and SUSY (see Motl, Woit and Dorigo) due to a recent preprint appeared on arxiv. Indeed SUSY is a relevant ingredient of string theory […]

9. Robert - July 25, 2008

Whats the fuss? The clause “without the strange coincidence of the gauge coupling convergence” implies that with the existing “coincidence” he doesnt want to bet against low energy susy …….

10. dorigo - July 25, 2008

Alejandro, good luck with the String conference, don’t come back all tied up though!

Lubos, I appreciate your answer, and the fact that opinions do vary. It is a healthy thing.

Andrew, Robert, I think the full quote in Peter Woit’s blog makes it clear that Bert does not believe in low-energy SUSY, regardless of coupling unification. At least, that is what I get of it.

Cheers all,

11. Alejandro Rivero - July 26, 2008

T, I’d submit if someone were able to show me how to get global SU(5) from local gauge SO(32). I am by now pretty convinced that all the stuff of the superstring gauge group is not the HEP “gut” gauge group, but a sort of quantisation of the flavour group. To produce the standard model gauges, Kaluza Klein in 11 dimensions does the work, and if we want to produce the unbroken standard model, SU(3)xU(1), we can do with 9 dimensions. I can not see any reason to need of the extra content E8xE8 etc that superstringers love. Some probably I will return clean 😀

12. Haelfix - July 26, 2008

SuSy still gives some of the best fits to dark matter models. So regardless about your philosophy on Grand Unification and the Hierarchy problem, there has to be something that fits the role of a Wimp.

And frankly, if the hierarchy problem turns into the hierarchy fact, thats pretty much ballgame for particle physics and most of us will need to look for a new job somewhere. There is no way theorists will ever be able to invent constraints that are as strong as minimality.

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