# Strings 2013 etc.

These days one can just about attend a wide variety of summer conferences from the comfort of one’s home or office, with talks appearing online more or less immediately after they are given. This week some possibilities to consider are:

• The big yearly string theory conference, Strings 2013, is in Seoul this week with about 279 physicists in attendance, talks are available here. As usual for recent string theory conferences, there aren’t a lot of strings to be seen. Perhaps these yearly conferences should be renamed something like “Conference on the latest topics popular among people who used to do string theory”. No sign at all of the landscape or string theory unification. For some understanding of why, see Life at the Interface of Particle Physics and String Theory, to be published by Reviews of Modern Physics, which makes pretty clear why the organizers of Strings 20XX now want to avoid this topic.
• The 2013 Lepton Photon conference is in San Francisco this week, talks here. To mark the occasion, Gordon Watts and Jacques Distler have thrown in the towel, paying up on their bet with Tommaso Dorigo that the LHC would find SUSY or other “new physics”. Tommaso has the full story here.
• For the more philosophically minded, the Templeton Foundation is funding a summer institute on the Philosophy of Cosmology, and you can follow the talks here. If thinking about time is your thing and you’ve missed out on the free summer amongst the redwoods, there’s still time to get in line for Templeton funds, with a few days left to apply for grants here.

Update: To round out the list, I should have included something for the mathematical physicists, this week’s Symmetries in Mathematics and Physics conference in Rio. Videos of the talks are appearing here.

Update: Jacques Distler has a posting here (or guest post here) conceding the loss of his bet with Tommaso Dorigo. Unlike some other theorists (e.g. John Ellis) who are arguing that everything’s fine, one just has to wait until 2015-6 for the higher energy LHC run, Distler is more of a realist:

…would I be willing to bet on the 2015 LHC run uncovering new BSM physics?

The answer, I think, is: not unless you were willing to give me some substantial odds (at least 5–1; if I think about it, maybe even higher).

Knowing the mass of the Higgs (∼125GeV) rules out huge swaths of BSM ideas. Seeing absolutely nothing in the 7 and 8 TeV data (not even the sort of 2-3σ deviations that, while not sufficient to claim a “discovery,” might at least serve as tantalizing hints of things to come) disfavours even more.

The probability (in my Bayesian estimation) that the LHC will discover BSM physics has gone from fairly likely (as witnessed by my previous willingness to take even-odds) to rather unlikely. N.B.: that’s not quite the same thing as saying that there’s no BSM physics at these energies; rather that, if it’s there, the LHC won’t be able to see it (at least, not without accumulating many years worth of data).

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### 20 Responses to Strings 2013 etc.

1. P says:

Hi Peter,

It isn’t any more right to say that string theory is just unification than it is to say that QFT is just the standard model. The field has given insight into a broad variety of topics in physics (maths, AdS/CFT, field theory dualities, strongly coupled gauge theories, etc etc).

In this sense, Strings 2013 absolutely is a conference about string theory. I’d challenge you to find more than 10 talks (other than the ones which seem to be from LHC and Planck experimentalists) which aren’t string theory outside the realm of unification or topics in QFT and gravity which owe many of their results to string theory.

Cheers,
P

2. Peter Woit says:

P,
I don’t think there’s any point in arguing now about what is “string theory” and what isn’t, since the term has become rather meaningless as it has morphed into “stuff that is kind of somehow inspired by something someone once found while working on string theory”, which covers all sorts of different things.

The remarkable thing about string theory unification is not just that it’s no longer a central part of string theory research, but that the most influential “string theorists” in the world, those who choose talks for Strings 20XX, now won’t touch it with a ten-foot pole.

3. leptonphoton says:

Lepton Photon used to be ‘Electron Photon’ in the good old days we all hanker for (when there were no blogs?). Technically I think I wasn’t born yet so no hankering for me. Is LP2013 exclusively about leptons and photons?

4. chris says:

the amazing thing about LP13 is that on monday the new SUSY and BSM search results were presented – the last round of new results before the update of LHC – and nobody seemed to care in the slightest. As the exclusion limits on various stuff inches upward – some of it into the 10 TeV range already – it seems that finally noone expects there to be anything but the SM.

5. nobsm says:

Therein lies the tragedy. It’s one thing to criticize ST/SUSY/etc as hype, and to say ‘no evidence for SUSY and BSM search at LHC’ but ‘no BSM’ is a tragedy for HEP.

6. Peter Woit says:

leptonphoton,

No, the conference for a long time hasn’t just been about leptons and photons. Maybe they should update the name…

7. Eric says:

I think it has become very clear that most likely the only superpartners which are light enough to be produced at the LHC are neutralinos and charginos. Unfortunately, the production rate for neutralinos and charginos in hadron colliderss is very low, so there is almost no chance of seeing these particles at the LHC. However, it should be possible to the lightest neutralino in direct dark matter experiments and to produce neutralinos and charginos at the furture ILC. So, I would encourage patience rather than the pessimism which is all too prevalent on this blog.

8. Bob Jones says:

I don’t think there was ever a time when string theory was just an idea about unification. Back in the late 1960s when string theory first got going, it was a theory of nuclear physics. Applications of string theory to mathematics can be traced all the way back to the days of bosonic string theory. String theory also led to the systematic development of two-dimensional conformal field theory way back in the 1980s.

It’s not right to say that the subject has “morphed” into something different. String theory has always been related to lots of mainstream topics in mathematical physics. Critics of string theory typically ignore this fact and focus on the more speculative aspects of the subject.

9. P says:

Hi Bob,

I absolutely agree. I think we’re in agreement, then, that the talks at Strings 2013 are essentially all about, or at least heavily inspired by, string theory.

Since Peter didn’t respond to my challenge: can you (or anyone else) find more than 5-10 of the ~40 talks that aren’t actually about or inspired by strings?

10. David M. says:

Well using a broad definition of string theory I would say the following weren’t exactly stringy talks:
Seibergs talk on 4d gauge theories seemed to me like a pure quantum field theory talk with connections to ST. I enjoyed it though, it highlighted the importance of line, surface, and higher dimensional operators in distinguishing different QFTs.

Komargodski’s talk (previous version can be found here:https://sites.google.com/site/zoharswebsite/home/recent-presentations) looks to be on the same topic of SUSY QFTs as does Sunjay Lee’s. Then theres Rychkov’s talk about bootstrapping conformal field theories. The bootstrap program is obviously related to string theory via ads/cft and in his presentation at the String-Math conference he mentioned the possibility of bootstrapping 6d SCFTs, but direct applications to ST didn’t come up this time.

Sara Pasquetti’s talk looks like its based on a recent paper where string theory only came up because topological strings were used to derive the partition function of the 5d theory on a product of spheres, but once again seems to fall more under QFT then string theory.

So I would argue that Pasquetti, Komargodski, Seiberg, Lee,and Rychkov all had talks that were more field theory with connections and applications to ST then ST talks. Thats not to say I don’t think they should be there, its all fascinating work with connections to string theory, but they do strike me more as QFT talks.

There is definitely a dearth of particle physics related talks. Cvetic is really the only one presenting on that subject. There were definitely more pheno talks last year, but given the lack of any good BSM news its not surprising either.

11. P says:

I also have Komargodski, Seiberg, and Rychkov not in the “string theory broadly defined” category, but one could argue for Lee and Pasquetti being within string theory for the reasons you mentioned, i.e. due to the usual ST SUSY gauge theory formal math interplay. But that’s a matter of taste, I suppose.

12. Shantanu says:

Peter one more conference(although with no slides)
Bruno zumino 90th birthday fest
http://ctp.berkeley.edu/brunofest/Schedule.html

13. Hello Peter,

thanks for mentioning the bet and its (logical, to me) conclusion. When I offered the wager, in 2006, I believe the large majority of my colleagues would have taken it. Now things have indeed changed dramatically. But let’s review critically the situation now and then.

What is it that we did not know then and know now ? That large swaths of the MSSM space are ruled out ? That there are no Z’ below a TeV ? That large extra dimensions were not just right there waiting to jump at us ?

The Tevatron had done a pretty decent job at showing that every bit of measurement was in accordance with SM predictions. But what really motivated me to offer the wager was observing the incredible agreement of low-energy observables in B physics, where new particles would have made their effects felt from quantum loops. I think we had all the hints that the LHC would be as successful as its predecessor LEP II in the same tunnel: deliver what it promised, and nothing more.

So if I look at the status of our knowledge then and now, I cannot see a qualitative difference. And indeed, that is why I was already reasonably sure we would not see new physics at the LHC. Of course, ready to be surprised, I put all my research time into sharpening the tools of CMS; but with a good dose of pessimism.

Why others had a different opinion ? Sure, theoretical indicia were important: the energy scale was the right one, if one believes naturalness arguments. But I think it has largely also been a sort of bandwagon effect. The LHC appeared such a beautiful new machine that it just was unthinkable it would fail to deliver what theorists assured us we’d find.

I urge everybody who sits in funding committees to consider quite soberly the new proposals of experiments and facilities. There is a large set of offers on the floor, but I believe it just is not the right time to take a decision now. We said we’d build the ILC with the right design parameters once we knew what SUSY particles we’d study. Now let’s hold our horses for a few more years. As beautiful as LEP II was, what do we know from it that we would not know anyway without it today ?

Cheers,
T.

14. Peter Woit says:

Hi Tommaso,

I suppose I should have joined you in the bet. My own point of view pre-LHC was that things like SUSY and extra dimensions not only lacked any evidence from places they should have already shown up, directly or indirectly, but that they were (and are) badly motivated ideas. All of such models I’ve seen introduce large numbers of new parameters and new structure, while not giving any answers to the questions about the SM we don’t understand. So, for purely theoretical and aesthetic reasons, besides the lack of indirect evidence, such things seemed highly unlikely to turn up at the LHC.

One reason I didn’t join your side of the bet was that it was broader, including any deviation from the SM. In particular, since we had not seen the Higgs, it seemed to me not at all impossible that there was something about the Higgs mechanism we were missing, something that would explain all those parameters that come with the Higgs sector. Maybe once the LHC started seeing evidence of the Higgs sector, something non-SM at 5 sigma would be part of it. So far that hasn’t happened, but that’s what I wasn’t willing to bet against back then (although I liked your argument that doing so would be win-win: either one got new physics, or some money).

I think the HEP community as a whole made a huge mistake allowing the LHC to be partially sold as a machine that would produce new dimensions of space (super or otherwise), black holes, etc. This was never going to happen, guaranteeing a heavy price to be paid in credibility down the road. The Higgs question though was very real, and more than enough to justify the project. If the LHC had been sold as purely a Higgs discovery and initial investigation machine, everyone would now consider it nothing but a huge success and if there’s a sensible plan for a follow-on machine, it would be easier to get support for it.

To my mind, the big question about a future machine is whether there’s an affordable one that can do a much better job than the LHC in studying the Higgs sector. I gather lots of people are working hard now at trying to figure that out…

15. divisi0n of labor says:

“string theory unification is … no longer a central part of string theory research”

http://stringpheno2013.desy.de/e209876/

16. Peter Woit says:

division of labor,

Funny how in that division of labor the people not doing string phenomenology get the big yearly conference, the $3 million checks, professorships at Princeton/Harvard and completely freeze out the string phenomenologists, while the string phenomenologists get the small satellite conference. From 2009, and I don’t think the situation has gotten better ” I once heard someone say the shortest joke is “string phenomenology”.” http://resonaances.blogspot.com/2009/06/boston-tea-party.html?showComment=1244898346677#c4807554018314481181 17. piscator says: “I think the HEP community as a whole made a huge mistake allowing the LHC to be partially sold as a machine that would produce new dimensions of space (super or otherwise), black holes, etc. This was never going to happen, guaranteeing a heavy price to be paid in credibility down the road.” I totally agree on this. This is also not the fault of string theory. For all the talk of string theory hype on this blog, over the last fifteen years the area of particle theory most guilty of prolonged and unsubstantiated hype is BSM. You can talk all you like about string unification, but string phenomenology papers do not have five thousand citations for failed models. Likewise, you will not find any speakers at String Phenomenology put forward to the public as great physicists of the age in the way that say Nima Arkani-Hamed or Lisa Randall are. “Funny how in that division of labor the people not doing string phenomenology get the big yearly conference, the$3 million checks, professorships at Princeton/Harvard…”

Watch the future. The strings conference is declining. Take away the 100 locals from Korea, and it had less than 200 people attending. It used to have 500 people and close registration months in advance. The young have voted with their feet. Few young people do the formal mathematical physics that is represented at Strings, and there are almost no jobs in this area.

18. billy says:

Dear peter , Can you explain why are you hostile against string theory ?
I think that The theory is highly constrained mathematically , It claims to be a final theory so why should one expect that we should have results now ? I expect that the human quest for a fundamental theory of nature to take a huge amount of time . Don’t you agree ? Second , Are all alternatives as satisfactory and well-developed as string theory is ? Why don’t you think that string theory is on the right track ?

19. Peter Woit says:

billy,

I wrote a book to answer these questions. It was written ten years ago, but things haven’t fundamentally changed.

20. fuzzy says:

Nice post, Peter!

In an old joke, a guy was sure he had lost his wallet in some dark street, but he was continuing to look under a lamppost, because it was easier. If we set the duality: HEP COMMUNITY=”the guy”; BSM=”wallet”; LHC = “lamppost” (and possibly DESPAIR=”laughter”) we have a picture of the way of proceeding in the last 30 years.

Note that I do not write intentionally what is dual to “dark street”, but this is not because I lack valid proposals (e.g., NUCLEAR PHYSICS, QCD, ASTROPARTICLE PHYSICS…) but because I think that anybody, working in high energy physics, should take responsibility in offering the best answer he/she can, rather than following canned responses from somebody else.

Incidentally, I note that you, Peter, have suggested the answer “HIGGS PHYSICS” here above. I respect this proposal but I am not sure that I find it convincing, since I do not see any good theoretical reason that this should lead us to BSM.