LHC Excludes SUSY Theories, Theorists Clinch Hands
    By Tommaso Dorigo | February 22nd 2011 12:03 PM | 70 comments | Print | E-mail | Track Comments
    About Tommaso

    I am an experimental particle physicist working with the CMS experiment at CERN. In my spare time I play chess, abuse the piano, and aim my dobson...

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    Both the CMS and ATLAS collaborations have already started to exclude meaningful regions of the parameter space of Supersymmetric models with the data they collected in 2010. And Physics World is on the news today with a online article by Kathy Mc Alpine, the famous rapper physicist who wrote the lirics and interpreted one of the biggest Youtube hits in the category of science popularization. If you have not watched it yet, please rush to do so now. Six million people (and counting) have done so before you already.

    Once you've watched the video, you can spend the rest of your coffee break reading the interesting piece by Kathy. Of course I love to sponsor it here, since she quotes me extensively, and with me two Italian colleagues (one of which I happened to co-tutor in his Ph.D. thesis, a couple of geological eras back).

    About the news: if you have not heard about it yet, an ATLAS paper appeared a week ago to discuss the search for signatures including muons and jets, while a CMS paper, appeared over a month ago, considered instead the missing Et plus jets signature. Curiously, the two searches ended up having an almost identical sensitivity to the SUSY parameter space (actually, with a slight edge by CMS), and yet this time ATLAS was more "lucky", seeing fewer events in their signal box than predicted by background expectations, while CMS got the worse of it, seing more events than they expected. The result ? ATLAS excludes a significantly wider chunk of parameter space.

    The ATLAS result is based on the search for events containing an energetic lepton (electron or muon), missing transverse energy, and three or more jets. This signature can be produced by a variety of supersymmetric decay chains, as well as by several standard model processes -most notably, top production (in light and dark green) and diboson production (in brown), as shown by the figure on the right. In it you can see the effective mass of the system of reconstructed bodies, which shows that the data (black points) are well reproduced by expected backgrounds (red line with uncertainty in hatched yellow), which is dominated in fact by ttbar production. A particular point of the SUSY parameter space would produce an excess of events, shown by the dashed black histogram.

    The agreement of data and standard model predictions is used to extract limits on Supersymmetry. In the figure below you see the exclusion by the ATLAS search as a full red line. The two axes show two relevant parameters of the SUSY space: these are the "universal" mass values of SUSY sparticles of spin 1/2 and 0. ATLAS sweeps away the previous limits by Tevatron and LEP experiments. The limit ATLAS expected to set  based on the analyzed dataset and analysis technique is shown with hatched line: as you see the difference is sizable. And this was only driven by observing a couple of events less than expected! This tells you that the search is statistics-limited, and that this year a further big jump in sensitivity is to be expected.

    CMS, whose result is also shown as a black curve in the plot above, studied events just featuring missing transverse energy and jets. This is known to be a priori the best search channel for "inclusive" Supersymmetric signatures at hadron colliders: not requiring a lepton increases backgrounds, but accepts the most signal. The reason for the large acceptance to signal events is that squarks and gluinos are coloured objects, and thus can be copiously pair-produced in the interaction of two regular hadrons. The chain of decays of pairs of such particles ends up producing jets and, if R-parity is conserved, a couple of neutralinos -particles that escape undetected and produce an imbalance in the transverse energy detected by the experiment. (I should mention that the ATLAS search is also sensitive to squarks and gluinos, but only when a chargino is produced in the decay chain, yielding an additional charged lepton. In this sense, the ATLAS search is more "exclusive", but that does not mean it should be more sensitive).

    In the figure you may check that the black curve (CMS exclusion) closely follows the expected exclusion of the ATLAS search... And CMS saw more events than predicted, so their observed result (black curve) is worse (excludes less) than they expected. The ATLAS figure does not show the CMS expected limit, unfortunately... (Wink).

    And what do theorists say ? A lot of things, as is also clarified by the Physics World article. However, I should mention here a very quick reaction in print, by our friend Ben Allanach, a theorist specialized in Supersymmetry. (Ben has been a guest in my blog a couple of years ago, with an insightful article on predictions for SUSY particle masses).
    A fresh off the press paper in the arxiv by Allanach uses the SUSY limits set by CMS to constrain the full space of parameters with a global fit to particle physics and astrophysics observables. I have no time to discuss the paper here, unfortunately, but Ben is always welcome to produce a new guest post on the matter! Curiously, Ben's article appeared in the arxiv on the same day that the ATLAS result also made its apparition. I am sure that Ben is presently using the ATLAS input for a further update of his fits right now!

    Let me finish this article by mentioning that in Kathy's article, I am quoted at the very end to say the following:

    "We will get in a crisis, I think, in a few years".

    What I mean is that although SUSY might be there and still be unreachable even by the LHC at full speed, if we see nothing in three years or so there will be a rush to abandon the sinking ship... The next few years are going to be quite interesting!!


    Hello Tommaso! Jester has posted the latest "preliminary results" from ATLAS on jets+MET:

    (The plot comes from the recent conference in Aspen, he has the relevant link to the talk.)

    I have heard that at least part of the reason why the ATLAS plot seems to have more sensitivity is that they estimate their background using only Monte Carlo, while CMS does something more sophisticated and data-driven. Is this true and can you comment on it?


    Hi Flip,

    I actually happen to know much more about the reason why the ATLAS reach is higher than the CMS one, than many in ATLAS do.

    What I can certainly say is that ATLAS has started using a very aggressive limit-setting limit, which is a power-constrained limit but with a less conservative result for limits which are within 1-sigma of the expectation. Other papers by ATLAS show a comparison of limits obtained with CLs, but this paper does not.

    What a lot of tosh!

    The reason that the CMS limit underperforms is because it uses alphaT, not because of a different statistical treatment!

    The CMS paper clearly states (see section 4.4 of ) that it would have done better if it had used variables optimised for susy discovery -- they give an example of two: Meff (which ATLAS used) and a delta-phi based variable (similar to, though not quite as useful as MT2, which ATLAS used).

    There may be a small effect from statistical treatments, but the main difference between the two analyses is that ATLAS looked for SUSY, while CMS looked to suppress QCD background. Read the atlas paper here:

    We certainly cannot complain at the speed with which the ship is sinking! The rats must be having their meetings behind their barrels, and one day they will all swarm over the side into the ocean ... I wonder how many can swim.

    Bonny Bonobo alias Brat
    CMS collaborator Konstantin Matchev of the University of Florida, Gainesville explains that new physics was expected between 1–3 TeV – a range that the LHC experiments have hardly begun to explore. In particular, he notes that of the 14 "benchmark" searches for supersymmetry laid out by CMS collaborators, these early data have only tested the first two. "In three years, if we have covered all these benchmark points, then we can say the prospect doesn't look good anymore. For now it's just the beginning," says Matchev. But not everyone is optimistic about discovering SUSY. "We will get in a crisis, I think, in a few years," Dorigo predicts, sceptical of the theory because it introduces so many new particles of which data presently show "no hints".
    Tommaso, are there really no hints at all in the data?
    My article about researchers identifying a potential blue green algae cause & L-Serine treatment for Lou Gehrig's ALS, MND, Parkinsons & Alzheimers is at
    Hi Helen,

    that you naively ask such a question to me means that you have no hint on how these big collaborations work! They crucified me in the past for orders-of-magnitude minor sins than the one you are asking me to commit.

    Bonny Bonobo alias Brat
    Sorry Tommaso, yes I have always been naive :)
    My article about researchers identifying a potential blue green algae cause & L-Serine treatment for Lou Gehrig's ALS, MND, Parkinsons & Alzheimers is at
    Dear Tommaso, this charade is extremely, extremely premature. I had personally had wishes that SUSY could appear super quickly - but they were always pure wishful thinking and I have always claimed that those possibilities were "less likely than yes" ie. below 50%. If you look at sensible scenarios studied in the literature, one needs an inverse femtobarn of data or more, not 0.035 of it.

    SUSY may still be there even if it remains invisible to the LHC, indeed. And yes, I don't hide that I will be convinced that SUSY is there even if the LHC doesn't find it. The LHC will only confirm or exclude effects at particular regimes - usually low energy but it's not quite accurate a description of the regime that may be excluded.

    What I have been scared for several years is the pseudoscientific propaganda of your kind trying to claim - without any justification - that not seeing SUSY at the LHC should imply that physicists shouldn't be allowed to work on SUSY or believe that it is a key feature of our Universe. There are many reasons to think it's the case and theorists whom I consider any good will continue to treat SUSY as an essential feature whether or not it shows up at the LHC.

    But those comments are premature. It hasn't been decided whether the LHC, at the standard luminosities where it's designed to run, finds or doesn't find SUSY. And it's damn plausible that already in half a year, the situation will be very different.

    Supersymmetry was known to be wrong already long before any experiment was performed. Supersymmetry and supergravity assume fermionic coordinates. But fermionic coordinates contradict Wheeler's space-time foam. The existence of space-time foam is one of the few consequences of quantum gravity that is model-independent and that cannot be discussed away.

    Whoever defends supersymmetry rejects space-time foam, and thus rejects either quantum theory, or general relativity, or both.

    Susanna, what you write is complete nonsense. First, quantum foam is just a vaguely defined concept, and it is not established as a part of physics by any empirically based methods. However, even if one decides that it's true in some form, any form that forbids fermionic coordinates to exist is clearly physically invalid.

    Supersymmetry may conceivably turn out to be irrelevant for the observations at the LHC but it is surely a framework that is at least as consistent as the non-supersymmetric field theories, and with the addition of general relativity and quantum mechanics in the picture, this advantage becomes even more pronounced. At the quantum level, supergravity is much more consistent than non-supersymmetric gravity.

    Assuming some naive form of quantum foam that prohibits fermionic coordinates is just a laywoman's prejudice and it can only to crackpottery.

    Vladimir Kalitvianski
    For those who are new and naive here, Lubosh is always right (by definition). We all should be happy to be exposed to his shining.
    Thanks, Vladimir, it's a refreshing experience to see you writing something that actually makes sense.

    Vladimir Kalitvianski
    No refreshing experience here - I was joking!
    Well, if zillions of monkeys are just randomly joking, jumping on banana trees, and randomly pressing buttons of a typewriter, they inevitable write Hamlet at some point, anyway. Congratulations.

    Vladimir Kalitvianski
    Take it easy, Lubosh, I always lie ;-).
    Wow, he really felt for that one! Kudos.

    Quite on the contrary, Anonymous. It is you who failed to recognize that Vladimir's comment was a more valuable piece of wisdom than anything you have ever managed to learn in your life.

    In fact, I have difficulties to imagine a left version of Lubos.

    I live in California.   The whole state is filled with people far worse on the left than anything he has said on the right.
    Ha, ha, ha. You do have real leftist in the US? You would fare much better if you had.

    The U.S. has been the leader of the modern civilization because such people were left to beg on the street, with an interruption of a few years, and my optimistic nature suggests that they're again returning to the status of beggars.

    A few decades ago, my homeland was less lucky.

    Lubos, we wait for your qualified analysis of the situation. As an expert you can certainly point to the errors and open questions in this SUSY analysis. We are all truly interested. Certainly also fans to the left or to the right :) If you are left, maybe I can be right, to keep the balance. Ulla.

    The early searches by CMS and ATLAS changed the best fit parameters of the supersymmetric standard model in its four subversions just by a dozen of percent in average. See my review of 3 articles that incorporate all the findings into a new fit:

    To suggest that low-energy SUSY has been ruled out would be preposterous.

    Lubos, your write that any form of space-time foam "that forbids fermionic coordinates to exist is clearly physically invalid." It is time that you stop repeating this Arkani-Hamed nonsense. This is neither "clear" nor "invalid". If we read this and all your other postings on the subject, we find that there is only one good argument for supersymmetry: that I am a crackpot laywoman because I state that it does not fit with experiment. This very deep argument, for which we all admire you, only shows: no woman will ever be worth to marry you.

    Now to the physics. At high energy, space-time "must be thrown out of the window". This is just how Arkani-Hamed talks about space-time foam. But at high energy, supersymmetry claims that space-time exists and has fermionic coordinates. Everybody can see that this is a contradiction.

    Well, it's plausible that no woman is worth marrying me - but believe me or not, this question has nothing to do with the existence of fermionic coordinates. Just to find another hole in your theory, Arkani-Hamed is married.

    Every single statement in your comment is wrong. The statement about the importance of the fermionic coordinates is not "Arkani-Hamed nonsense" but an insight known to every physicist who has a clue about his field.

    Supersymmetry doesn't claim that spacetime exists. Quite on the contrary, in the twistor pictures e.g. Arkani-Hamed and others have been working for a few years, supersymmetry (and even superconformal symmetry and even the infinite-dimensional Yangian symmetry) exists without spacetime. But the idea that something could be more fundamental than spacetime is totally unimaginable to the people like you. You're just way too limited.

    Wow, now I remember why I left physics.

    Too bad you didn't take all your soulmates with you.

    In what spacetime is supersymmetry more fundamental than spacetime? Do you exist outside spacetime? Or have you simply discovered the mind of God? And what do you mean by "fundamental"? If supersymmetrical "particles" are only discovered by high energy collisions, would that not make them "emergent" rather than "fundamental"? Or is your speculation based on the assumption of a universal Big Bang?

    "In what spacetime is supersymmetry more fundamental than spacetime? Do you exist outside spacetime?"

    Supersymmetry is more fundamental than spacetime in the world volume of Matrix theory; in the twistor space such as CP^3|4; in CFT when we talk about the AdS spacetime; and in lots of other situations where spacetime (and locality in spacetime in particular) isn't incorporated to the defining mathematical structures. It's just the case that modern physics says that supersymmetry is more fundamental than spacetime - while spacetime physics is just one among many approximate descriptions. I know that it is counterintuitive for people who are not familiar with state-to-the-art physics but that doesn't diminish the fact that it is certainly the case.

    "Or have you simply discovered the mind of God?"

    Surely getting closer to it.

    "And what do you mean by "fundamental"? If supersymmetrical "particles" are only discovered by high energy collisions, would that not make them "emergent" rather than "fundamental"."

    No, whatever symmetry or other concept appears at higher energies *is* fundamental. High-energy physics is fundamental while low-energy physics is approximate and possibly emergent. Am I the first one who tells you?

    " Or is your speculation based on the assumption of a universal Big Bang?"

    I haven't written any speculations, just scientific facts, so the question above makes no sense.

    Vladimir Kalitvianski
    The most important lesson that should have been learnt from elementary particle physics is that there is no elementary (fundamental) free particles in space but elementary excitations in compound systems.
    If the universe evolves as a pressurized (energetic field) space and heats up, rather than cooling from a hot dense state (Big Bang), then the designation of "fundamental" or "elementary" (particle or excitation) appearing as a result of high energy collisions would be backward, wouldn't it? Or does that not make sense?

    Hi Lubos,

    I will limit myself to commenting about your last statement. I do wish with all my heart that it becomes true!

    Great, Tommaso. Let me just say in advance that when it happens, it would be fair if you contributed Jester a part of the money for his $10,000 bet against me that he will lose because you have been as violent a SUSY-mudslinger as he has been and he doesn't deserve to pay for the whole world of irrational critics.

    I will gladly take part in the bet if I also take part in the wins if Motl loses. See

    Dear Tommaso, do you really think your title is faithful to the real situation? Not even "starst to exclude", which would be inappropriate as other colliders started the search. SUSY is NOT excluded, not even the simplest MSSM incarnation is. What's the point of your title? To attract attention? Do you think truth should be sacrificed that easily? Do you consider the average reader of your posts stupid? It's good to see LHC making good strides towards discovery (of SUSY, that's my bet) and this machine will keep on excluding chunks of parameter space till it finds new physics, won't it? Why didn't you write similar posts entitled, Tevatron excludes Z's, or Tevatron excludes a heavy fourth family? They would be at a similar level (or be even better, as SUSY is far wider in scope). You can and should do better!!!

    Anonymous, I could ignore your rant, but the matter of fact is that the title is correct.
    SUSY is not a theory, but a framework of theories. Different incarnations of SUSY depend
    on different values of its parameters. And It so happens that two of the interesting
    benchmark points of the MSSM have been excluded by the LHC searches. Not just "one more bit
    of the chunk", but two points which had been taken as representative of a significant portion
    of the parameter space.

    As for the Tevatron, I did similar announcements in the past. They are "scandalistic", if you like, but they do attract attention, and attention to HEP is all I want.
    So, a more appropriate title would be : "Tommaso claims LHC excludes SUSY Theories, SUSY theorists laugh and give him the finger"

    In the theoretical world, it is always possible to laugh and send a middle finger.   Somewhere out there, a theorist is still laughing at anyone who disbelieves in the aether.    People need to start using 'hypothetical' more than 'theoretical'.
    "So, a more appropriate title would be : "Tommaso claims LHC excludes SUSY Theories, SUSY theorists laugh and give him the finger"

    Really, this susy theorist is laughing and giving the finger at the experimentalist, who is in touch with the real world...sounds like the trait of a madman.

    Sorry, you got it wrong. The finger is addressed at the bad journalist, not at the experimentalist.

    I have to agree that the title is very misleading. SUSY has in no way been excluded, or even disfavored. Sure, particular "models" which correspond to specific points in the parameter space have been excluded, and thus the title is not incorrect in the most strict, technical sense. However, there is still a lot of viable parameter space which will be explored in the next couple of years. Really, if the SUSY partners are on the heavier side, it may be that it will have to wait until the shutdown/upgrade to run at higher energies to be discovered. Another thing that should be pointed out is that there doesn't seem to be any signs of other new physics either. We should expect that if not SUSY, then there should be some new physics. It will be very strange if two years from now, nothing has been found.


    To keep things in proper perspective, let's recall that effective Lagrangian analysis is often invoked to gauge how new physics at high energies may influence low energy observables. Modifications induced by new physics at several TeV would be described by non-renormalizable interactions appearing as terms organized by their mass dimension in the effective Lagrangian.

    This type of analysis and precision measurements of EW parameters point out that it is quite possible that no new physics will show up at the TeV scale. Rather than confirming the "desert" hypothesis, the absence of new dynamical structures may be the signature of a nearly massless sector, ultra-weakly coupled to SM and a likely manifestation of non-baryonic dark matter.


    Hello all,

    while I am sure that all but few of you who react to the title of this post being "misleading" (in particular those who hide themselves and their dubious reputation behind anonymity) do so in earnest, I think you really need to be taught something here.

    You neglect to realize that we are doing journalism here. Scientific journalism, if it is to live (and I am not talking in economical terms, at least not strictly) needs to conform to some important rules of the game. Titles need to attract the reader's attention, and are not supposed to provide the full picture -not in six words! They should rather faithfully represent what is being dealt with in the body of an article (I would have been wrong to write "Susy looking less sexy lately" in the title, because I would attract many perverts and fail to catch the attention of physics-hungry geeks), but attract attention.

    By neglecting to read my article -which rather clearly explains that SUSY is a framework of theories and not a single one, and thus that it might well never be excluded by experimental searches, as Ervin correctly explains (among others) in the comment above- you are committing the very same sin that many nowadays commit in this information-clogged world: being superficial.

    This result is of course an immediate consequence of Larsson's theorem

    Sorry Tommaso, you don't need to repeat yourself in explaining what you do (much less teach us a lesson). I don't think your readers need to be attracted by flashy innacurate titles. There are many people out there with a keen interest in particle physics who deserve a little bit more respect, in my opinion. There are many kinds of journalism and yours is pretty good in general, but as I said already, I think you can do better without happily embracing the worst practices of common journalism. Your title is equivalent to "Gaddafi ousted from Lybia!" Well, it sure would attract attention and if you read carefully you'll discovered that, well, he hasn't been really ousted, right?

    Dear anon,

    I insist that my title is correct, albeit "sensationalistic". ATLAS and CMS have ticked off the list of representative benchmark points of the MSSM a couple of important items. So LHC did, in fact, rule out SUSY theories. Two of them. SUSY is not a theory, but a framework of many different theories, with widely varied phenomenological manifestations. If you were to consider SUSY a single theory, you should accept that it both provides an explanation of dark matter, and it doesn't, depending e.g. on the neutralino mass, or R-parity conservation.

    Vladimir Kalitvianski
    You won't believe it but my discovery of the second atomic form-factor is even more sensational than experimentally excluding SUSE.
    Grammar comment to all the grammar rants about the title (I guess it'll be conveniently ignored, but still):

    Afaik, english doesn't have a plural indefinite article. It does have a plural definite article.

    So, saying
    "LHC Excludes SUSY Theories"
    "LHC Excludes more than one SUSY Theories"

    while saying
    "LHC Excludes the SUSY Theories"
    "LHC Excludes all of the SUSY Theories".

    Do you see the semantic connotations or should they be explained for you as well? Oh, btw, yes, LHC is excluding susy theories.

    Why don't susy fundamentalists stop being hypocrites, and write instead about what really annoyed them in this article? Why can't you follow Lubos' example who says that "I don't hide that I will be convinced that SUSY is there even if the LHC doesn't find it" and then goes on to accuse anti-susists for spreading pseudoscience?

    (Sorry Tommaso, but I have a certain soft spot for susy and semiotics, especially when combined.)

    On second thought, writing that "LHC Excludes the SUSY Theories" would have also been a semantic mistake, as it'd imply that their number is finite.


    thank you so much for making this point, which I thought was trivial, mistakenly. Yes, I did make leverage on the subtleties of English grammar in my title. The fact that I am Italian and that most of my critics are English-speaking natives compounds their guilt. Oh, well - most of them are americans, many of which are well-known for not knowing their own grammar rules. (uh oh now a whole different hell opens up ;-)

    Ha Ha, Tommaso The tip, here,.............. 'When in a hole, stop digging!' Guilt is always trouble, in my understanding of people's mis-use of the term.... Aitch
    Well, Tommaso, so you really think Particle Physics journalism needs sensationalism? I don't think so. In my book, if from reading just the title of an article you get the wrong impression of its contents, then the title is badly chosen. You can still blame me for not taking the trouble of reading the article, but that doesn't make the title any better. I can instead blame you for not being careful enough. If after seeing your post a not well informed journalist publishes an article claiming that SUSY is dead, she would be to blame, but you wouldn't be innocent.

    The title is as bad as if, after Tevatron Higgs searches, you used "Tevatron excludes Standard Models". And is even epistemologically wrong, as theories like these cannot be properly excluded, just pushed aside to higher energies.
    Concerning which, I'm fond of SUSY myself, but if LHC doesn't find sparticles I'll stop believing SUSY has anything to do with TeV physics and the hierarchy problem (although it might still be relevant at the string scale). But there is a long way to go before one can claim LHC puts SUSY in big trouble.

    I'll try to stop myself from further participation in this pointless discussion, but how exactly did you get the wrong impression from the title? Cms and atlas ARE lhc experiments, and they are excluding regions of the possible parameter space of some of the most popular susy flavours, as can be proven by recent official presentations of their results. So, yes, they ARE excluding susy theories.

    If you think the title means "lhc excludes susy", then you are probably more prone to fall into false assumptions than the majority of non-susy-believer readers, who didn't get the wrong impression.

    (Btw a discussion arguing that the excluded area doesn't mean anything for the non-excluded one might have made more sense, but no, it'd have been too scientific :p )

    Well, tulpoeid, Tommaso himself agreed the title is sensationalistic. Ask him why he concedes that.

    "(Btw a discussion arguing that the excluded area doesn't mean anything for the non-excluded one might have made more sense, but no, it'd have been too scientific :p )"

    That's exactly what I said: LHC is excluding chunks of parameter space of SUSY models (why Tommaso talks about points, I've no idea) and that's what if should happen before it finally hits the jackpot. If you don't like SUSY and want to put flashy titles to your posts, do it. But then don't complain if you get criticized for irresponsible behaviour.

    And I think I made my point sufficiently clear so I'll stop.

    First of all, "I'll stop" does not mean anything. As I explained elsewhere, until you dress up with a nickname that characterizes your comments here, you are nothing but one instantiation of a multi-body entity. Who knows whether it was the same person writing the above comments ? I can trace you down, but politeness and lack of time suggests me to do otherwise. But you do not lose anything if you participate in a discussion with a nickname other than "anonymous". Please do so the next time and it will be more pleasant discussing.

    Second, I talk of specific points - and that's the whole point - because some specific combination of the parameters have been elected as "benchmark" ones by an agreement of theorists and experimentalists. And the excluded region encompasses two of them. This is relevant. The SUSY theories "LM4" and "LM1" (I might be wrong on the precise acronym here -sorry have no time to check) have been ruled out. Please note: the theories. Plural. SUSY theories have been excluded.

    "Well, tulpoeid, Tommaso himself agreed the title is sensationalistic. Ask him why he concedes that."

    I'm sorry, but he said "I insist that my title is correct, albeit "sensationalistic" ". And for the purpose of this discussion I don't care if he said this or not, but I'm annoyed by fighting over the inaccuracy of just a title which by the way happens to be accurate, while there's an elephant in the room.

    Also, I had to read twice more through all of the comments until I discovered this piece that you refer to: "It's good to see LHC making good strides towards discovery (of SUSY, that's my bet) and this machine will keep on excluding chunks of parameter space till it finds new physics, won't it?" which is not exactly what I said. Never mind.

    But, in the end, is there any reason to believe in SUSY other than willingness to believe? I would say that it would be an elegant universe (if I'm not breaking a trademark) the one where SUSY is true, but unfortunately I don't see why should we think that this is the case for our universe.

    Hi Tommaso,

    you keep repeating that "SUSY is not a theory, but a framework of many different theories", and this statement is certainly correct. But it does not prevent your title to be deliberately misleading. As many readers before me already stressed, the LHC results only allow to rule out regions in the parameter space of SUSY models. They certainly do not rule out (yet) the whole models, let alone the whole concept of SUSY. No matter how much you stretch your English language, your insistence in calling "theories" what actually are specific points in the parameter space of SUSY models smells like willful obfuscation.

    To make an example, no theorist in his sane mind would call the (in)famous SPS1a benchmark point "a theory". But perhaps that use of language is common among experimentalists. Would you stand by it?

    Cheers, Ptrslv72

    sorry T., before criticizing your creative English I should have checked mine ;-)
    The second sentence reads "But it does not prevent your title from being deliberately misleading"

    Oooooh, I had not even read this comment of yours, which summarizes it all:

    "(...) some specific combination of the parameters have been elected as "benchmark" ones by an agreement of theorists and experimentalists. And the excluded region encompasses two of them. This is relevant. The SUSY theories "LM4" and "LM1" (I might be wrong on the precise acronym here -sorry have no time to check) have been ruled out. Please note: the theories. Plural. SUSY theories have been excluded."

    that's the whole point of my earlier post: only in your creative English is "benchmark points" the same as "theories".

    Cheers, Ptrslv72

    Hello Ptrslv, welcome back -it's been a while, long time no talk.

    So yes, we can discuss whether those benchmark points are "theories" or just zero-measure bits of the parameter space. I might even end up agreeing that changing the gaugino mass from 200 to 300 GeV makes little difference -to me, for sure, it does not make any.

    However, there is a lesson to learn from this diatriba. Some SUSY supporters object to the fact that one may consider the different manifestations of different SUSY parameter space points "different theories", claiming that the general structure is the same. Experimentalists see the ugly rear end of the matter: they have to work their butt out to investigate wholly different signatures, but the prize is zero: irrelevant chunks of a infinite parameter space are ticked off, not disproving anything at all.

    I prefer the attitude of those theorists like Sven or Ben, who produced this week two meaningful re-analyses of the global CMSSM observables in the light of the new exclusion, getting to learn something important from the new data. Still, the common attitude is that the exclusion actually "increases the global likelihood of the global fits" !! This in a frequentist sense, of course - and it is due to CONDITIONING TO THE EXISTENCE OF SUSY.

    Quite interesting -albeit a bit taliban ;-)


    Well, in the Standard Model the signatures of Higgs boson decays can be wholly different depending on the Higgs mass - but certainly you would not argue that the SM with M_H=115 GeV and the SM with M_H=160 GeV are "two different theories" - or would you?

    This said, I agree that one should not consider all points in the "infinite parameter space" of SUSY models to be equally reasonable, and that at some point in the future low-energy SUSY might be considered to have been ruled out. But I guess we are nowhere near that point now.

    Cheers, Ptrslv72
    Here my doubts about the supersymmetry

    Well, to do counterweight, I have also uploaded a vixra-style paper ;) but I am still confident we will find some gauginos.

    Hello Alejandro
    Nice to meet you after long lasted interrupting.
    The base of my concept you can see here.
    Al the best

    And let me point out that benchmark points tend to reveal more about the prejudices and feelings of the people (theorists) who invented them, and there are no guarantee that any set of them are representative or cover parameter space in any meaningful way.

    If nature is supersymmetric, it chose one point. Whether it looks like others or fits our notions or the random fluctuations of previous measurements was presumably not part of the choice.

    Great, we're abandoning the era when the opinion of susy opposers didn't count, for the era that the opinion of susy theorists doesn't count as well :)))

    Ah... and to all: I just published a short note discussing this thread, in my Greek blog. Have fun, if you know the language (or if you trust google translate -but please don't).

    Cheers all,
    I have to defend Mr. T here - the first sentence of his post fully clarifies the title, nor is the title really misleading as it refers to SUSY theories. SUSY is correctly and ajective modifying the word "theories". Instead, your subconcoius, probably influenced by where you stand on SUSY in the first place, has inserted the word "all". It is unlikely that anyone who reads this blog on a regular basis would genuinely confused. And if someone found this through a google search, they probably have some idea too (if not they'll be running away at first sight of that graph and the many big words).

    Anyways.. whats become of Les Horrible Cernettes?

    Supersymmetry has been suggested independently in 1971 by Juri Gol’fand and Evgeni Likhtman, in 1973 by Dmitri Volkov and V. Akulov, and in 1974 by Julius Wess and Bruno Zumino. In 1976 Peter van Nieuwenhuizen, Sergio Ferrara, Daniel Z. Freedman, Stanley Deser, and Bruno Zumino suggested a local supersymmetry called supergravity. In 1981 Edward Witten has shown that supersymmetry can solve several shortcomings of Grand Unified theories. In 1984 Michael Green and John Schwarz have shown that string theory and supersymmetry can be combined. This is the superstring theory. In 1995 Edward Witten has shown that the membrane concept can agree the 11-dimensional supergravity with the 10-dimensional superstring theory. Both theories are limit cases of an 11-dimensional M-theory.

    Supersymmetric theories predicted that the elementary particles of the standard theory of particle physics (leptons, quarks, photon, gluons, W- and Z-boson, Higgs boson) have supersymmetric partners. This supersymmetric particles (called neutralinos, photino, gluinos, Winos, Zinos, squarks, and sleptons) were all predicted to have rest masses between 50 and 300 GeV (billion electron volts).

    Now the ATLAS Collaboration of the LHC (Large Hadron Collider) presented data (arXiv: 1102.2357) which do not confirm the gluino. It would have been detected if its rest mass were less than 700 GeV.

    I am not so surprised that signs of light supersymmetric particles have not been detected. I predict that supersymmetry will not be confirmed. My arguments are the following.

    (1) The main reason for supersymmetry is that it can explain some shortcomings of minimal Grand Unified Theories, i. e. the mass-hierarchy problem (i. e. the fact that W- and Z-boson do not have rest masses of 10^15 GeV, although they should have “eaten” (coupled to) the Higgs bosons of Grand Unification) and the non-observation of the proton decay (lower limit: mean proton lifetime of 10^33 years).

    But this argument requires that there is Grand Unification.

    In 1997 I suggested (Modern Physics Letters A 12, 3153 – 3159 = hep-ph/9708394) a generalization of quantum electrodynamics, called quantum electromagnetodynamics. This theory is based on the gauge group U(1) x U’(1). In contrast to QED it describes electricity and magnetism as symmetrical as possible. Moreover it explains the quantization of electric charge. It includes electric and magnetic charges (Dirac magnetic monopoles) and two kinds of photon, the conventional Einstein electric photon and the hypothetical Salam magnetic photon. The electric-magnetic duality of this theory reads:

    electric charge — magnetic charge
    electric current — magnetic current
    electric conductivity — magnetic conductivity
    electric field strength — magnetic field strength
    electric four-potential — magnetic four-potential
    electric photon — magnetic photon
    electric field constant — magnetic field constant
    dielectricity number — magnetic permeability

    Because of the U(1) x U’(1) group structure and the Dirac quantization condition e * g = h (unit electric charge times unit magnetic charge is equal to the Planck constant), this theory is hard to agree with Grand Unification. Although a group such as SU(5) x SU’(5) is in principle not impossible.

    (2) Another reason for supersymmetry is that it can explain the existence of (anti-symmetrical) fermions in an otherwise symmetrical theory (such as Special Relativity and General Relativity).

    However, it has long been known that a generalization of General Relativity which includes anti-symmetry is Einstein-Cartan theory. The affine connection of this theory includes not only the non-Lorentz invariant symmetrical Christoffel symbol but also the Lorentz invariant anti-symmetrical Torsion tensor.

    Within the framework of a quantum field theory, the Torsion tensor corresponds to a spin-three boson called tordion, which was introduced in 1976 by F. W. Hehl et al.: Reviews of Modern Physics 48 (1976) 393 – 416.

    In 1999 I discussed (International Journal of Modern Physics A 14, 2531-2535 = arXiv: gr-qc/9806026) the properties of the tordion. Moreover I sugested that the electric-magnetic duality is analogous to the mass-spin duality. This analogy reads:

    electric charge — magnetic charge – mass — spin

    electric field constant — magnetic field constant — gravitational constant — reduced Planck constant

    electric four-potential — magnetic four-potential — metric tensor — torsion tensor

    electric photon — magnetic photon — graviton — tordion

    (3) Supersymmetric theories including superstring and M theory have not much predictive power. For example, so far no one has shown that these theories predict the empirically obvious Naturkonstanten-Gleichung (fundamental equation of unified field theory, Modern Physics Letters A 14, 1917-1922 = arXiv: astro-ph/9908356):

    ln (kappa * c * H * M) = −1 / alpha

    where kappa is the Einstein field constant, c is the speed of light, H is the Hubble constant, M is the Planck mass, and alpha is the fine-structure constant. By using the WMAP−5 value

    H = (70.5 +/- 1.3) km / (s * Mpc)

    (E. Komatsu et al.: Astrophys. J. Suppl. Series 180 (2009) 330 – 376) the left-hand side yields

    ln (kappa * c * H * M) = – 137.025(19)

    which is within the error bars equal to

    - 1 / alpha = – 137.035 999 679(94)

    The Naturkonstanten-Gleichung predicts the Hubble constant to be

    H = 69.734(4) km / (s * Mpc)