Friday, June 22, 2012

Higgs and drawing boards: Overbye right, Strassler wrong

Dennis Overbye of the New York Times wrote one of the articles about the possible announcement of the discovery of the God particle on July 4th (press release by CERN), before all the talks at ICHEP 2012 in Melbourne between July 4th and July 11th:
New Data on Elusive Particle Shrouded in Secrecy
First, I find this whole "sport" of talking about the Higgs rumors unbelievably stupid. In December 2011, we were told that there were excesses and the overall combined statistical significance of the excesses could have been seen to be 4.5 sigma or so. This translates to the probability of a "false positive" – probability that the excesses were just flukes – equal to 1 part in 100,000 or so.

For half a year, sensible people who followed the announcements and who know basic statistics knew that there was a 99.999% chance that there's a new very Higgs-like particle whose mass is near 125 GeV. It also follows that the probability is extremely high that new excesses caused by this particle must be found in the 2012 data, too. Because the data in 2012 already contain "slightly more information" than the data in 2011, it's obvious that the ATLAS and CMS folks see very similar excesses as they did in 2011, and perhaps a bit stronger ones (plus minus some errors because the statistical significance is a quantity with some uncertainty and noise, too).

All these claims follow from the December 2011 announcements. We're kind of 99.999% certain that there must be excesses in the 2012 data, too. So why would we use rumors and blogs to decide whether the 2011 excesses were flukes? The 2011 excesses only have a 0.001% chance of being wrong; rumors have approximately 50% chance to be wrong. How could you possibly use the latter – unreliable rumors – to decide about the validity of the former – the statistically significant and "almost certain" cold hard data? It's crazy. It's a textbook example of a tail wagging the dog. One should use the strong, 99.999% certainly real 2011 excesses to conclude that the rumors now are correct. But doing it in the other way is just silly.

It's even crazier if you realize that the rumor actually appeared on a website of the New York City's most notorious crackpot in high energy physics, Mr Peter Woit. It has appeared on a blog whose 95% is composed of shameful lies, distortions, misintepretations, and extremely dumb attacks against the world's best scientists. A blog run by an immoral jerk who refused to accompany his girlfriend to the police station once she was raped by a black rapist. A disgraceful parody of a human being.

It's just distasteful that someone would quote this individual.

Thank God, Dennis Overbye at least avoided to mention the name of this pathetic website and its sucking webmaster who has spent years by trying to "punish" the high-energy theoretical physics community for his own lack of talent to do physics himself, for his being just a mediocre pseudointellectual who can't do real science. In fact, Overbye sensibly mentioned that one should be careful about buying stuff from the blogosphere uncritically. He deserves to be praised for these points, too.

But that's not the primary topic I wanted to talk about. Matt Strassler was driven up the wall by Overbye's article, especially by one sentence, and wrote this reaction:
The New York Times Gets The Higgs Wrong
The relevant sentence that Matt Strassler didn't like was the following one:
This, all agree, is the boson’s last stand. If the December signal fades, it probably means that the Higgs boson, at least as physicists have envisioned it for the past 40 years, does not exist, and that theorists have to go back to their drawing boards.
In my opinion, this is a perfectly valid description of the situation. If one could eliminate the Standard Model Higgs boson over the range between 115 and 700 GeV or so – and the LHC has recorded enough data by now to do so if no Higgs is there; lower masses have been excluded previously; higher masses tend to produce an ill-behaved theory – then it would be the last nail in the coffin of the Higgs boson as physicists have envisioned it for 40 years.

This "envisioning" obviously describes the Standard Model Higgs boson or any Higgs sector that contains a particle that is sufficiently close to the Standard Model Higgs boson. In fact, one could even say that the term "Higgs boson" should only be used for the kind of minimal enough theories with an elementary scalar field that Peter Higgs was working with in the 1960s; very different theories of a Higgs sector may fail to have the right to use the "Higgs" trademark. But if you don't want to discuss what "sufficiently close" exactly means two sentences ago, you may just decide that "as physicists have envisioned for 40 years" means nothing else than "as incorporated in the Standard Model". In my opinion, it's pretty much clear that this is roughly what Overbye meant. Some vagueness in the sentence is indisputable but whatever exact meaning we choose, we may see that Overbye's sentence is at least approximately accurate.

Now, Strassler has protested that Overbye didn't distinguish the Standard Model Higgs and a general Higgs. He actually did distinguish them. A whole "envisioning" sentence has been written down to emphasize that we could only exclude the dominant, minimal enough model of the Higgs boson.

Also, Strassler says that he wouldn't have to return to the drawing board if there were no Higgs with the SM cross sections in the interval that the LHC may probe and exclude by now. Oh, really? He wouldn't have to return to the drawing board?

To show that he wouldn't have to return, he cites several obscure papers with models whose Higgs sector could remain undetected through the end of 2012. You could perhaps say that these papers' authors have already returned to the drawing board – to find a loophole we could need in the situation that with a 99.999% certainty won't occur, namely that the Higgs will be excluded throughout the a priori plausible Standard Model range.

However, even if you imagine that the Standard Model Higgs excesses will disappear and the particle will be excluded, which is nearly impossible to consider at this moment, even the people who have proposed the models with an undetectable Higgs sector will have to continue to work with their drawing boards. Why? Because what they have found so far just can't compare to the Standard Model Higgs boson when it comes to the amount of convincing arguments that these models could be right. These models aren't unique, they look arbitrary from many viewpoints, so at this moment, we have no good reason to think that either of these models is right. They aren't replacements of the Standard Model and even the hypothetical (now impossible) exclusion of the SM Higgs in the whole interval would fail to be enough to make them replacements for the Standard Model.

That's why Dennis Overbye would be right even if he were referring to the people who write such unusual papers about the Higgs sector: even these people would have to return to the drawing board because the work they have done so far simply isn't good enough.

All the comments above are academic discussions because the Higgs boson is there and chances are significant – but it's not guaranteed – that an official discovery announcement (a formality at this point) will arrive in July. If that won't happen, we will hear about the official Higgs discovery by the end of 2012 or in January 2013. For people who know what's going on, the Higgs boson is already a sure thing.

I honestly don't understand what made Strassler so upset. Perhaps it was the implicit statement that the Standard Model is the actual golden template that one may take somewhat seriously and other theories – especially if they don't have any particle closely resembling the Standard Model Higgs boson (supersymmetric models' lightest Higgs is very often SM-like and the corners of the parameter space in which the differences are huge are already dead!) are just bizarrely looking, non-unique alternatives whose individual likelihood to be right is vastly lower than it is for the Higgs boson. Some of them aren't excluded at this point but that's something else than saying that they're Standard Model's serious competitors. They're not.

But if Overbye wanted to make this implicit point, he would be right. The Standard Model is a vastly more established and motivated effective theory than any of the obscure models that Matt cited which is why it's correct that it's talked about much more seriously in serious newspapers than many of the obscure models that Matt mentioned. Models aren't created equal and they become even more unequal once we acquire more data. And the Standard Model was the single theory that got the strongest possible boost by the LHC so far.

By adjusting just one previously unknown i.e. newly measured parameter in this model, the Higgs mass, one may correctly describe all the data that the LHC folks have published so far. The deviation of the experimental data from the Standard Model including its God particle never jumps above 2 sigma. No other model can claim this kind of success which is why it's right that the Standard Model plays such a special role in the discussions about the LHC data and theories that explain them. Only a discovery of new physics (beyond the Higgs boson) may change this situation. It may happen soon, perhaps next month; but such a discovery may be far, too.

What Overbye wrote about the Higgs boson and the drawing board was true – despite some flexibility in the meaning – and it was pretty standard, too. It's strange to see that some other folks are irritated by completely different things in the media than your humble correspondent.

And that's the memo.


  1. Hm, maybe I read the "going back to the drawing board" phrase too many times mentioned by some "crazy revolutioners" who want to throw everything that is known in (fundamental) physics and proved right out of the window... :-/.
    Now I see that Dennis Overbye probably meant it quite different ...

  2. Dude... the problem was being black or being a rapist? Because he also was probably tall/large/strong/hairy or whatever.

  3. I would like to ask a question that might sound naive, but it is something that has concerned me since the excesses have been reported.

    The question is how do we know the excesses are really the HIggs Boson, i.e. a scalar particle - the first such particle to be discovered, rather than something else?

    Given the way the LHC works - it is very much a sledgehammer to crack a nut - I would doubt they can prove any new particle is a scalar? I don't even know how you would prove the scalar property experimentally, perhaps looking at polarisations? But I don't know the LHC is capable of doing that?

    Please correct my misundertandings - rather than the AGW model assumptions like - it must be true because we cant think of anything else, lol

  4. All these nouns and adjectives obviously made the problem worse. Only because you have apparently never been raped and you don't have a clue what it means, you're ready to invoke preposterous suggestions that the extra adjectives don't matter.

    I wrote one of the adjectives to make sure that this wasn't some crazy love affair with a charming cosmopolitan fan of women that could have been reinterpreted as a rape by some creative storyteller. This was a brutal rape with everything one can imagine, the kind of rape that is punished by instant death penalty in many countries. For the sake of his own convenience, Mr Woit made sure that this rapist could freely continue in his hobby.

  5. Dear Dilaton,no, he meant exactly this thing and I believe he is right. You may have grown allergic to the phrase and I am allergic myself but if there were no Higgs boson, this would be a rather shocking surprise and paradigm shift in particle physics, indeed.

  6. Dear Adrian, in quantum physics, every localized object has some spin, it's its internal angular momentum, after all. One may prove that the spin is integer or half-integer because the rotation by 720 degrees is totally indistinguishable from no rotation.

    The conservation of angular momentum together with the rules how the angular momentum is being added means that only a particle whose spin is either j=0 or j=1 or j=2 can decay to two photons.

    Obviously, the decaying particle cannot have a half-integer spin because this couldn't decay to two photons.

    Actually, the j=1 case may also be excluded. A massive spin 1 boson can't decay to 2 photons, either. The reasons are more technical and are known as the Landau-Yang theorem, see e.g. page 4 of this document for proof:

    This leaves j=0 and j=2. Now, theoretically, one may show that j=2 elementary particles must be graviton of a sort because of a gauge invariance and Lorentz symmetry. But assume you don't buy any fancy theory arguments. Still, the j=2 case will be excluded if it is observed that the new particle may decay into two j=1/2 fermions such as a bottom quark pair. It's because the chances of dividing j=2 to twice j=1/2 are also zero.

    To summarize, j=0 is the only possibility. Yes, it is the first fundamental scalar we know but there's nothing wrong with fundamental scalars. For example, string theory - with the highest criteria of consistency - predicts lots of them. The only true issue with them is that they typically want to become heavy. Their low mass isn't protected. That's why we talk about the hierarchy problem and its solutions, especially supersymmetry.

  7. ... whoops, so I`m glad that we have at least one higgs in the pocket ...;-)
    Thanks for these further explanations and clarifications Lumo :-)

  8. Pleasure, Dilaton. Let me celebrate Higgs as an aroma of string theory in this way.

    If you look at literature and/or this very thread, you will find people who have problems with elementary spinless (j=0, scalar) particles such as the Higgs. They invent pseudoarguments why they shouldn't exist, why they must be composite if they exist, and so on.

    But string theory shows that they not only exist but they play very important roles. All of the landscape with its structure is labeled by scalar fields, sort of. Scalar fields are behind everything that looks like an adjustable coupling constant - these scalar fields are moduli. Moreover, string theory probably predicts a whole army of weakly interacting scalars - axions - which cover a whole wide interval of masses on the log scale.

    The Higgs boson-like particles are also geometrized in string theory in many ways - deviations of radii of circles away from the self-dual radius; distances between branes, and so on, and so on.

    Before this 125 GeV Higgs, we hadn't known any elementary scalar - a single string that looks like a spinless particle - in the world. String theory, unlike others, was predicting that such particles should exist. We are probably starting to discover them.

  9. Yep, cheers ... :-)))

  10. Hey Shannon, where is your sweet little one ... ;-) ?

  11. But Dilaton, I am the sweet little one :-)... just grown up. My ipad cannot download my cute face but soon I'll get the new Microsoft Surface and it wont be a problem anymore.

  12. Please note that in addition to all the reasons listed by Lubos, the spin of a particle can be determined expermimentally ;

  13. Peter Woit writes, "I understand very well that what I write on my blog creates an uncomfortable situation for people at CERN and those working on the experiments."

    Why doesn't Peter Woit get a life, or take up a hobby, instead of making professional scientists uncomfortable?

  14. A good rhetorical question, of course. A rhetorical obvious answer is that he is a fucked-up shithead who feels comfortable if others feel uncomfortable because that's a way for him to punish the other people for the fact that he is such a piece of shit himself.

    And because there exists a whole market appreciating the shit such as himself, instead of cutting his fucking head, it makes him doubly comfortable.

  15. Seeing this *&%$# ?*&%$ popping up at Prof. Strassler s site turns my stomach and makes me vomit :-(

  16. I always wonder why Prof. Strassler does not throw him out but politely chats with the TROLL of trolls ...:-/