Press releases claiming that a “test for string theory” has been found appear with some regularity, notwithstanding the fact that no one actually knows how to test string theory. The latest one comes from the University of California at San Diego, where the press office today put out a press release entitled Physicists Develop Test For “String Theory”. The story has been picked up by the media, appearing here and here and probably soon in many other places.
This latest claim about a “test for string theory” is quite remarkable and even more bogus than usual. It is based on a paper which has nothing to with string theory and doesn’t do a string theory calculation at all. The paper first appeared on the arXiv last April with the title Falsifying String Theory Through WW Scattering, and was extensively discussed here. In October a new version of the paper was put on the arXiv, with a changed title Falsifying Models of New Physics via WW Scattering (and this was discussed here). I’m guessing that the removal of the claims about string theory from the title was due to a referee at PRL not being willing to go along with such a title, although maybe there’s more to the story and if so I’d be curious to know what it is.
The year is just beginning, but I’m already willing to award this press release the title of “most outrageously misleading string theory hype of 2007”. It is going to be extremely hard for anyone else to match it.
Update: The Distler et. al. overhyped press release continues to spread misinformation to the public, getting more and more ridiculous as it spreads. The blog Tech.Blorge.com reports about string theory that:
Until now, experimental verification has not been possible; but researchers at the University of California, Carnegie Mellon University, and the University of Texas are planning a definitive test with the future launch of the Large Hadron Collider…
This then made it to Slashdot, which put out a story under the headline String Theory Put to the Test, which starts off with:
… scientists have come up with a definitive test that could prove or disprove string theory. The project is described as…
and then goes on to give a description of the LHC project.
I think the people responsible for this should be ashamed of themselves.
Update: Not to be outdone by UCSD, Carnegie-Mellon has also issued a press release about this. More also here and here.
Update: More at Digg, SpaceDaily, Science Frontline, etc., etc.
Update: Yet another major university issues a misleading press release about this: from the University of Texas Team of Theoretical Physicists Develop a Test for String Theory.
Update: The Resonaances blog has a posting explaining what is actually in the Distler et. al. paper, while describing the press releases, with their pretensions that the authors have found a way to test string theory at the LHC, as “hilarious”.
Update: Sabine Hossenfelder wrote in to point out that New Scientist now has an article about this, with the title New particle accelerator could rule out string theory. The article quotes hype from string theorist Allan Adams as well as from Distler, ignoring Distler’s co-authors and describing him as “leader of the team” that solved the problem no one else had been able to solve, figuring out how to test string theory at the LHC. Funny, but as far as I can tell, this great advance in the testability of string theory is not being covered at any of the string theory blogs. I wonder why…
The authors are saying it tests Lorentz invariance, analyticity, and unitarity, the ingoing assumptions for ST.
I guess the first one means relativity is valid, the last one means all operators are unitary (?); I have no idea what analyticity means.
Are any of these likely be violated at the LHC?
In general, unitarity of the S matrix puts a bound on the growth of cross sections with energy, the so-called Froissart bound. In particular, if the SM-calculable bound is heavily violated by experiment (LHC) then the SM is inferred to be embedded into something more general which takes over at high energies. Personally, I strongly believe that the latter will happen on grounds that have nothing to do with susy, Xdim, and string theory for that matter.
It’s a pity the authors chose to advertise this way since, after all, they did a very interesting work. Most of us used to think that in a low-energy effective quantum field theory any higher-dimensional operators consistent with the symmetries are allowed. Now we know that at least the signs of certain operators are constrained by very general arguments. Only very bizarre theories could violate these constraints (and string theory is not bizarre enough). There is also the earlier paper by Arkani-Hamed et al. [hep-th/0602178], which discusses these matters from a somewhat more general perspective.
You have a funny typo there, never heard of WWW Scattering 🙂
In October a new version of the paper was put on the arXiv, with a changed title Falsifying Models of New Physics via WWW Scattering (and this was discussed here).
Thanks Bee. I guess I thought the author’s paper has more to do with scattering bogus claims via the World Wide Web than scattering W particles…
The UCSD press release by Amy Pavlak and Kim McDonald has as its title
“Physicists Develop Test for ‘String Theory’”
The press release said in part:
“… “Since we don’t have a complete understanding of string theory, it’s impossible to rule out all possible models that are based on strings,” said Rothstein. …”.
The title and the statement by Rothstein seem to be contradictory.
Further, the press release said that the “… test sets bounds on … three mathematical assumptions –
Lorentz invariance (the laws of physics are the same for all uniformly moving observers),
analyticity (a smoothness criteria for the scattering of high-energy particles after a collision) and
unitarity (all probabilities always add up to one). …”,
so
it seems that the press release could just as well be entitled “Physicists Develop Test for ‘Bootstrap Theory’”,
about which Peter Woit said in blog comments in July 2006:
“… the bootstrap program … was wrong, and wrong in very much the same way that string theory is … If you look at Chew’s writings from that era, there’s a lot of the same kind of wishful thinking you see in string theory. Not knowing about asymptotic freedom of gauge theory, you could argue that the bootstrap was “the only game in town” … To some extent, lots of people who had worked on the bootstrap and early versions of string theory just picked up where they had left off when string theory came back into fashion in 1984. There really only was a period of about 10 years (1974-1984) when QFT was completely dominant. …”.
It is also interesting that Ed Witten studied under David Gross and
David Gross studied under the leading advocate of bootstrap theory, Geoffrey Chew.
Tony Smith
http://www.valdostamuseum.org/hamsmith/
Well, the first link quoted above is a rather imprecise but not dishonest account IMHO. In particular, I appreciated the sobering quote by Distler:
“If the bounds are satisfied, we would still not know that string theory is correct,” said Distler. “But, if the bounds are violated, we would know that string theory, as it is currently understood, could not be correct. At the very least, the theory would have to be reshaped in a highly nontrivial way.”
Of course, there is a small step still needed to fill the gap from what Distler acknowledges and the fact that nobody really takes seriously any theory implying violation of those three principles, and the article fails to make it.
T.
So does this mean that now any test of general relativity is now also going to be a test of string theory? And that Hulse and Taylor received their Nobel prize for a successful test of string theory?
I guess it’s not just a string theory problem, I mean, how do we know that any “new breakthrough” that’ll be claimed even on LHC will be anything but a desperate attempt to make something out of some nonsense just to give even some justification for all the money spent on building it?
Ari Heikkinen said: “… how do we know that any “new breakthrough” that’ll be claimed even on LHC will be anything but a desperate attempt to make something out of some nonsense just to give even some justification for all the money spent on building it? …”.
LHC is almost certain to produce results with respect to Higgs and the Tquark that will substantially improve understanding of the Standard Model.
The Standard Model is very far rom “nonsense”.
Increased understanding of it is very important with respect to real (i.e., testable by experiment) physics,
and (in my view at least) fully justifies the cost of building the LHC so that its enegy/luminosity regions can be explored and better understood.
As to “how do we know” claimed results of LHC will or will not be “nonsense”,
it is the same as with all accelerator experiments:
You read the papers, look at the data, and study the analysis techniques. If you find something that doesn’t look right to you, then say so and if your criticism is correct it will eventually become part of the results.
There WILL be data that if properly analyzed WILL increase our understanding of the Standard Model, and, since that is what the LHC was designed to do, it WILL be worth the money spent on it for that purpose.
There is a big difference between deciding to spend money on a machine to do a specific task (for the LHC, to explore the Standard Model in a given region of energy and luminosity)
and
spending 90% of high energy theory money on something that is substantially divorced from experimental results, and has produced no such results for decades, and is sociologically operated like a private club.
Tony Smith
http://www.valdostamuseum.org/hamsmith/
Tommaso,
I think there actually is an honesty problem with the Distler quote. His paper does not involve any string theory calculation in any way, so claiming a “test of string theory” is very problematic. In addition, as far as I can tell, what seems to have happened with that paper is that a PRL referee made them change it to remove the claim from the title about having a “test of string theory”. If this is right, to issue a press release about the PRL paper describing it as a “test of string theory” takes real chutzpah. If there’s another explanation for why the paper’s title was changed, I’d like to know what it is.
Ari and Tony,
Please try and keep your comments on-topic.
Tommaso said:
“the fact that nobody really takes seriously any theory implying violation of those three principles”
But at least a few people take seriously loop quantum gravity, which as I understand it does violate at least one of these principles….
Ok, I confess I did not read the paper 🙁 shame on me!
I guess I am getting dangerously close to having to rely on incorrect press accounts to know what is going on, at least in
string theory.
As a matter of fact, I remember discussing in my blog (guess with who, with Jacques Distler) the very issue of theoretical papers being too cryptic for a “normal” experimentalist to even conceive reading. If I recall correctly, he claimed that it was not string theory’s fault, because it has never been easy for experimentalists to read cutting-edge theoretical papers.
T.
Tommaso,
Actually that paper is pretty readable, partly because it doesn’t involve string theory. Some experimentalists might actually find it more readable than many theorists, since it is a story about the behavior of scattering amplitudes. This is closer to what experimentalists have real experience with these days, unlike theorists who often spent much of their careers working on more speculative stuff.
Peter,
The point I was trying to make (ok, perhaps it was badly worded as an example) was that upfront announcements of scientific “breakthroughs” is nothing new. It’s been done throughout the history by scientists, the media and by others, not just by string theorists.
Speaking of the announcement in question, don’t they claim this one could only prove string theory wrong, not right (Quote: “But, if the bounds are violated, we would know that string theory, as it is currently understood, could not be correct.”) ?
So if they think they can prove string theory wrong this way then what’s the problem? Also, the pdf you link (on arxiv) still reads “Falsifying String Theory Through WW Scattering” so what’s wrong with that?
Ari,
I put two links there. One is to the original version of the paper, with the claim about string theory in the title, the second is to a revised version of the paper uploaded several months later, where the title has been changed to remove the reference to string theory. Given the timing of this, it seems likely that the revised version is the refereed one, and that the referee is responsible for insisting on the changed title.
You might want to go back and read the extensive discussion about this whole topic that occurred here and that I linked to, involving one of the authors of the paper. I don’t want to repeat all those arguments, but the gist of the matter is that the assumptions made by these authors are actually the fundamental ones made in QFT. So, what is actually true is that if their bounds are seen to be violated, it is QFT, not string theory that is falsified. These same assumptions apply to perturbative string theory, but since one doesn’t really know what non-perturbative string theory (M-theory) is, they don’t apply to string theory in general.
My attempts to comment anonymously keep getting rejected, I’m not sure why.
Here are two things that are being overlooked in this discussion:
1. Yes, both QFT and string theory have these basic properties, but not necessarily every theory does. LQG, for instance, is sometimes claimed to violate Lorentz invariance.
2. These bounds reveal ways that low-energy physics is sensitive to very high-energy physics. It is true that in QFT these positivity criteria are always satisfied, so QFT would be falsified by violations of them. However, it’s not the case that in low-energy effective QFT these criteria are always satisfied. So what is falsified is that at very high scales, the theory describing our world is not a QFT. But we already know that, because of gravity! So QFT is already falsified. Given that QFT is falsified, we can ask what are other sensible theories of high-scale physics. One is string theory. Violation of these positivity conditions would, then, falsify string theory. This is not trivial. They would not necessarily, for instance, falsify LQG.
onymous,
Sorry about your problems with the spam filter (Akismet). The new version of WordPress has a newer version, which may have different behavior. Unfortunately it is is completely unconfigurable, and it does sometimes tag comments as spam for no obvious reason (sometimes it does this to MY comments…). I do generally check the spam queue once or twice a day, so if you just wait a while, your comment should appear after a while.
I just don’t think it’s accurate to say that violation of these bounds would falsify string theory (and, if you look at the wording in the published version of the paper, I think you’ll see the authors don’t say this, perhaps because a referee wouldn’t allow them to). What might be falsified is perturbative string theory (and presumably this is what the authors mean by the locution “generic models of string theory” used in their paper), but that is already falsified. One needs some sort of non-perturbative string theory or M-theory to get the kind of string theory backgrounds needed to get realistic physics. Not knowing what this M-theory is, you don’t know if it will satisfy the relevant assumptions.
Ok, I got your point, the first three versions of the paper in question are titled “Falsifying String Theory Through WW Scattering” and claim “If no light resonances are found, then a measured violation of the bound would falsify string theory.”.
But in the fourth version of the same paper the title was changed as “Falsifying Models of New Physics via WW Scattering” and the claim was changed as “As a corollary, if no light resonances are found, then a measured violation of the bound would falsify generic models of string theory.”.
As far as I can recall from Greene’s book, there wasn’t any mention of “generic models” of string theory, so exactly what’s meant by that?
“generic models” of string theory doesn’t actually have any well-defined meaning, as far as I know. It’s a bizarre locution I’ve never seen anywhere else, and was presumably introduced here to satisfy a referee who told the authors that their assumptions were not obviously satisfied by all string theory models.
As I explained in my previous comment, the problem is that only for perturbative string theory (and some unrealistic non-perturbative versions) do you have any kind of definition of the theory, and thus can check whether it satisfies the assumptions being made. For the kind of fundamental theory that string theorists hope exists and produces standard model physics, the existence of such a theory is purely conjectural, and one doesn’t know if it will satisfy the assumptions.
Yes, I was just about to post about this misinformation. You have to admire the sophistry involved in these kinds of press releases. Since string theorists claim that string theory susbsumes all the rest of physics, it therefore follows that any test which confirms any theory anywhere in physics necessarily confirms string theory.
Good thinking. That kind of incisive reasoning will surely get us to a Theory Of Everything “real soon now”…that is, if we don’t experience The Singularity first. Or find WMDs in Iraq…
In related news, I recently saw a non-black non-raven.
I have not read the paper (& probably would not understand it) but the press release reads as a form of lying to me. In the release, facts are selectively stated in such a way as to mislead people who are not experts in the field. The release is written in such a way that they encourage the layman to jump to erroneous conclusions. In my opinion, here is an analogy of what they are doing.
I claim that I have an investment strategy that can return your investments plus 100% in as little as 2 months. Furthermore I have a scientific test that was used to validate my strategy. It showed scientifically that the return on your investment will always be positive. Of course some investors will be more successful in using my strategy than others. So just send me a few thousands dollars & I will give you my scientific investment strategy.
Is this a form of fraud? I say yes & the press release uses a similar argument to imply the test will validate string theory when in fact it will just show string theory is one many different possibilities and outcomes. And one of the possibilities that will be still open is that string theory is not even wrong.
Why would LQG be Lorentz-invariant? It’s not a theory of flat spacetime. For an enlightening discussion, see http://www.lns.cornell.edu/spr/2003-11/msg0056792.html . Someone well known to NEW readers makes a cameo appearance.
I guess what people mean by “Lorentz invariant” is “Lorentz invariant in the limit of flat spacetime”. By the way, are you sure that that thread is not some kind of forgery designed to suggest that LM doesn’t understand basic GR?
GR (as well as string theory, which is also generally covariant) contains Minkowski spacetime as a solution. On the other hand, it is not clear if LQG can produce a flat Minkowski spacetime as a solution. In fact, there is a claim that the DSR is a limit of LQG and that the Lorentz violating effects in DSR can be tested experimentally (Lee Smolin keeps mentioning GLAST and other experiments). Hence, if the Lorentz violating effects are found experimentally it would be an indirect evidence of the LQG. The Distler, et. al. paper claims that the Lorentz violating effects can be tested at the LHC as well. If such effects are found the perturbative string theory would be invalidated. If they are not found, theories like LQG and DSR would get a big blow but string theory would still survive, although this would not “prove” string theory.
I find rather amusing Peter’s insistence on the inquisitor referee cutting off any reference to ST. It looks as if he was that referee ;). The paper was finally accepted with a revised title AND (quote from the latest version): “argument completely revisited, stronger and more pertinent bounds given”.
This version thus make stronger connection to tests of New Physics at LHC, via WW scattering, including ST and any other candidate for a High Energy completion of the SM which obeys LI, Unitarity and Analyticity. There are a few technicalities which are not the case to discuss now (like a heavy Higgs scenario). However, as a matter of principle, the logic I think is clear.
Namely, tests of GR are of course tests of low energy ST (and also low energy LQG), but also tests of any other *classical* theory of spacetime and low energy physics. What’s propossed in this paper is a test of the high energy behavior of scattering amplitudes and hence of high energy ST, since the latter is one of the few theories (and some claim perhaps the only one) we have to complete the SM (including gravity) in the UV. Furthermore, if the way out of ST (as Peter claims) is thru a yet non-existent M-theory, violations of the bounds will put strong constraints on the possible non-perturbative definitions of ST, which by itself is, needless to say, extremly important/interesting.
G
The old filter in WordPress was triggered by multiple links or some notorious subject lines.
The new Akismet goes after comments that have multiple exclamation marks. It also filters out very short posts that look like they were bot-generated for driving up ranking of single website (typical one is “interesting point, I agree”)
I guess what people mean by “Lorentz invariant” is “Lorentz invariant in the limit of flat spacetime”. By the way, are you sure that that thread is not some kind of forgery designed to suggest that LM doesn’t understand basic GR?
From what I recall of that spr thread (you might be able to find some comment by myself there, I don’t remember), this was one of the few occasions when I agreed with LM. He disagreed with people who claimed that diffeomorphism symmetry is empty just because you can choose curvilinear coordinates in Newton theory. Like a theory with global phase symmetry is a gauge theory, because you can choose different coordinate systems in different fibers 8)
A freely falling observer sees a Minskowki spacetime. GR has a local Lorentz symmetry in this sense.
Garbage, the fact that the test needs a heavy Higgs is not a tecnicality, since data suggest a light Higgs.
Anyhow, violations of unitarity etc at the Planck scale would give effects 100000000000000000000000000000000 smaller than what LHC can measure.
Furthermore, hep-th/0602178 presented the basic idea earlier and correctly.
For quite an interesting idea about a possible reduction of Poincare group to its subgroup as a fundamental symmetry (implying that CP also ceases to be a symmetry) see the Very Special Relativity of Glashow and Cohen. See also the little article here.
Shame is the main thing missing in all areas of modern culture. It’s one of those passe’ emotions like love and loyalty. But don’t you feel good about yourself?
-drl
Is this the reasoning?
Suppose the Standard Model is an effective theory valid upto some scale A.
We can add higher-dimension terms to the SM Lagrangian and put bounds on the coefficients of these terms.
Suppose those bounds are found to experimentally violated, and suppose our assumption that the SM effective theory is valid to some scale A is still true, then it must be that one or more of Lorentz invariance, analyticity of the S-matrix, etc., is violated and string theory is cannot be true.
The assumption that the SM effective theory is valid to some scale A and not some lesser scale B is presumably checked by the same set of experiments that find violation of the bounds on the coefficients of the higher-dimension terms?
Thanks in advance for clarifications!
Please, this is not the place to discuss various people’s confusions about the role of the Lorentz group in GR. In the paper in question here the Lorentz group has to be a global symmetry, this is not the case in GR.
Garbage,
So, it’s true that a referee wouldn’t allow the paper to be published with a title claiming that its authors had a test that could falsify string theory? If so, don’t you see a bit of an ethical problem with the authors having their universities issue press releases based on publication of the paper in PRL entitled “Physicists Develop Test for “String Theory””?
Arun, these constraints come from Quantum Field Theory. So, if LHC can only probe energies at which some QFT applies (the Standard Model or whatever else), these constraints are automatically satisfied. To test if quantum gravity violates locality/unitarity/etc, one must do experiments sensitive to quantum gravity. But if we knew how to directly test quantum gravity, we would have no need of inventing indirect tests.
Trying again to post this:
“So, if LHC can only probe energies at which some QFT applies (the Standard Model or whatever else), these constraints are automatically satisfied.”
No, this is not true, unless I misunderstand what you’re getting at. An effective QFT can perfectly well describe everything happening at LHC energies, but the constraint can still be violated because the UV completion is something more exotic. In that case the effective QFT will have some unusual signs, but this doesn’t mean it’s not a valid effective QFT for low-energy physics. This is sort of the whole point of this type of study, as emphasized in the Adams et.al. paper (hep-th/0602178): analyticity tells you about how far-UV properties manifest themselves in IR behavior. In this way it is possible (but not likely!) that properties of quantum gravity could make themselves known at much larger distances, very indirectly. Unfortunately this only happens if the theory of QG is exotic enough.
Also, above: “Anyhow, violations of unitarity etc at the Planck scale would give effects 100000000000000000000000000000000 smaller than what LHC can measure.” This isn’t clear to me either: do you have some particular example of a nonunitary theory in mind? In general modifying quantum mechanics is dangerous, e.g. the Banks/Peskin/Susskind argument that superficially plausible-looking modifications of QM lead to order-one violation of unitarity even at low energies (http://www.slac.stanford.edu/spires/find/hep/www?j=NUPHA,B244,125).
onymous’s point in his first comment above seems fair enough: Basically, if I understand rightly, if physics at high (Plank scale) energies is described by a quantum theory (of point particles, strings, or whatever) then Lorentz invariance, analyticity and unitarity imply certain positivity constraints in effective QFT descriptions at lower energies, and in particular in the Standard Model. These can apparently be tested in WW scattering, and if they are found to be violated it implies that a quantum theory description at Plank scale (with the aforementioned 3 properties)doesn’t exist. Since string theory is supposed to have these properties, it in particular gets invalidated. Peter’s objection that string/M-theory hasn’t been constructed yet (at least at the nonpertubative level) is strictly speaking correct, but to me it seems excessively trench warfare-like. If the constraints are found to be violated in WW scattering it would certainly be a heavy strike against string theory as a road towards describing Plank scale physics.
Kudos to the authors for coming up with this interesting and potentially important result. But the string-hype way in which it is being presented in the press is lamentable. Casual readers will come away with the impression that string theory has finally made a testable experimental prediction, just like e.g. electroweak theory predicting the vector bosons and their masses. The limited nature of the “prediction” in this case should have been emphasized, and the authors can’t escape some responsibility for this not having been done.
“…imply certain positivity constraints in effective QFT descriptions at lower energies, and in particular in the Standard Model.”
Er, I guess that should have been “…and in particular at energies above the standard model ones but still accessible at the LHC.”
The SM itself, being a QFT, automatically satisfies the positivity constraints…
“Anyhow, violations of unitarity etc at the Planck scale would give effects 100000000000000000000000000000000 smaller than what LHC can measure.”
As pointed out by onymous (although the reference to Banks et al. deserves further comments on), this is by no means totally clear. For instance, violations of LI generates dim
Peter,
I posted a longer comment. Not sure what happened. There is something strange going on here. Unfortunately I posted it as I wrote it and I dont really feel like writting it again. Hope it can be retrived, otherwise it will be left to the reader’s as an exercise to fill the (much longer) gap…
G
Let us assume that quantum gravity is at the Planck scale (10^16 TeV) and violates unitarity/analiticity/causality/etc: it would give effects suppressed by 10^16 TeV.
But LHC is sensitive to new operators suppressed at most by 100 TeV. Operators induced by quantum gravity are too small to be seen. Whatever is their sign, it can be approximated with zero: LHC is not testing quantum gravity. LHC is testing QFT. Any QFT (whether or not it comes from strings and whether or not it is the Standard Model) predicts no violation of causality, no Vedic spirits, etc.
Discovering Vedic spirits at LHC would be very interesting, but a paper that tells “if LHC sees Vedic spirits we would have to rethink string theory” is not very interesting.
I’d like to comment that Lorentz invariance can be violated spontaneously in the ordinary framework of local QFT based on the
manifestly Lorentz-invariant action. As is well known, the regulator theory can remove all ultraviolet divergences, but it is usually rejected as unphysical because it violates the unitarity of the physical S-matrix. However, this belief is not true if the regulator masses are complex. That is, what is violated in the relativistic complex-ghost field theory is not unitarity but Lorentz invariance! This fact was found 36 years ago. Please see N. N., Prog. Theor. Phys. 116 (2006) 873 or hep-th/0609206. Earlier references are contained therein.
amused wrote:
Basically, if I understand rightly, if physics at high (Plank scale) energies is described by a quantum theory (of point particles, strings, or whatever) then Lorentz invariance, analyticity and unitarity imply certain positivity constraints in effective QFT descriptions at lower energies, and in particular in the Standard Model. These can apparently be tested in WW scattering, and if they are found to be violated it implies that a quantum theory description at Plank scale (with the aforementioned 3 properties)doesn’t exist.
To which I add : doesn’t this argument assume that there is nothing beyond the standard model until the Planck scale? If WW scattering at LHC shows something new, then (in the absence of string theorists) wouldn’t we be normally looking for new particles at the LHC energy or a little higher rather than drawing implications for the Planck scale?
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Sorry about that G, but the rest of your comment seems to have vanished into the ether. I’m afraid that this blog software, like most others, has problems when you try and use the “less than” symbol. It inteprets it as opening an HTML tag, which never gets closed, so I guess it just deletes the symbol and everything after it. If someone knows of some way the software can be modified to not behave like this, let me know. Otherwise, people should just be warned to be very careful using “less than” or “greater than” symbols, realizing that WordPress may do something very undesirable when it encounters them.
Hi Garbage,
One can of course use < for < and > for > as per standard HTML.
Arun,
As I understand it, the argument in the paper doesn’t make any assumption about where the new physics shows up; it could be anywhere between the SM and Plank scales (although it shouldn’t be too close to the SM scale, otherwise some complications arise according to the paper). The point is that if the physics at some or other high energy scale scale is described by a quantum theory with S-matrix having the usual properties, then that alone implies certain constraints on the effective QFT descriptions of physics at lower energies (specifically, on the coefficients of a couple of terms in the general expression for a chiral Lagrangian describing a spontaneously broken electroweak gauge theory provided the Higgs mass isn’t too light). These bounds can apparently be probed by WW scattering at the LHC. Say the bounds are found to be violated in some future experiment at energies above the SM. That would imply that the physics at any higher energy scale, and in particular at the Plank scale, can’t be described by a quantum theory with S-matrix having usual properties (otherwise the bounds wouldn’t have been violated). Since string theory is supposed to be (a road towards) such a quantum theory, it would be pretty much dead as a consequence.
“press release”,
I don’t get your point in your last comment. The paper doesn’t claim to be saying anything specific about the structure (operators etc) of whatever theory describes physics at the Plank scale.
amused,
here are a few other observations that would similarly falsify current theories (including string theory): a 4th generation of quarks only, a W that moves faster than light, new vectors that do not fill an adjoint representation, perpetual motion, an anti-commuting boson, a new lepton doublet without its neutrino, nonconservation of energy, antigravity, time machines, a fundamental particle with spin 3, etc.
Why do you think that WW scattering is more interesting?