Thursday, February 09, 2017

Some Higgs impostor fake news

I want to start with a tweet by the famous particle physicist Lisa Randall that is two days old:

Through a digg tweet, she was referring to the article in Vice's Motherboard:
Why the Higgs Boson Found at the Large Hadron Collider Could Be an ‘Impostor’
by Farnia Fekri. All three key folks in this "story" are women: Lisa Randall, Farnia Fekri, and Usha Mallik, an Iowa experimental particle physicist who is the main heroine in Fekri's article. I need to emphasize it in order to be sure that the PC people won't accuse me of doing too little to promote the ties between science and the scientifically inferior gender. ;-)

Even though there were some other reactions among Lisa's followers – not really folks who follow particle physics in most cases – and I will discuss their reactions, my response was very similar to Lisa's. The title is fake news (and the body of the article contains some diluted solution of it). Well, it is a falsehood at least to the extent that the negation of the proposition is much more true – and it is a much more important truth, too. What's going on?

By late 2011, the LHC had already accumulated a sufficient number of collisions so that the folks could analyze those with two photons at the end rather finely and they found an excess of events with two photons that seem to arise from a decay of a new boson of mass \(125\GeV\). In other words, the invariant constructed from the two photons' four-momenta \(p^\mu,q^\mu\)\[

(p_\mu+q_\mu)(p^\mu+q^\mu) = m^2

\] was apparently equal to \((125\GeV)^2\) in many more cases than for other values of \(m\). Because a Higgs boson had to be discovered for the Standard Model to be experimentally completed as a consistent theory and this mass was consistent with everything else, I told you that a Higgs of this mass was a sure thing, although some people weren't this sane yet. ;-)

Yes, the formality occurred on the Independence Day in 2012: a sufficient number allowed both ATLAS and CMS to independently claim their 5-sigma discovery. (One detector had 4.8 or 4.9 but it's really an irrelevant historical coincidence now.) The Higgs was first discovered through the decays to \(\gamma\gamma\) i.e. two photons or \(ZZ\), two Z-bosons, heavier and equally neutral electroweak siblings of the photon.

Because the mass was determined and the final state included the pairs of spin-one bosons, people could be sure about a new particle, its mass, and its interactions with the pairs of spin-one bosons. For the particle to be a Higgs boson or "the Higgs boson", it needed to have many other interactions – including those with fermion pairs – equal to the theoretically predicted value.

As the experiments at the LHC continued, they have proven that many more interactions of the new particle are exactly as strong and have exactly the same properties, up to the error margins comparable to dozens of percent, as the Standard Model predicted. So doubts that it should be called a Higgs boson gradually evaporated.

So far it really looks like it is "the Higgs boson", i.e. a Higgs boson with the exact properties determined by the Standard Model that has no extensions, cousins, heavier or charged siblings, and other things. Experiments boldly yet humbly say that the world seems boring and the theorists are 50 years ahead of the experimenters because a flawless confirmation of theories written down 50 years ago is the best thing that the experimenters may do in the 2010s (naughty teenager decade or whatever is the right name for the teens) – while they will only be able to address some ideas we may already be sure about now around 2060. ;-)

This result, "everything seems compatible with the Standard Model", may be interpreted in various ways, i.e. as an argument against specific theories that try to replace the Higgs boson with something else or modify it heavily. Such "heavily alternative" theories that nevertheless want to be compatible with the \(125\GeV\) diphoton or \(ZZ\) signal are basically known the Higgs impostor models. A man is just making fun of us, is jumping inside the detectors, and pretends that he is Peter Higgs. ;-)

OK, I need to reverse this joke because 99% of the readers who also read the mainstream media would take it literally. No, dear brainwashed readers, the impostor isn't a man. It is a particle whose behavior resembles the behavior of the Higgs boson. It may have a wrong value of the spin or parity or be composite – but the properties may accidentally resemble the CP-even, spin-zero, elementary Higgs boson we assume that the new particle actually is.

I could give you links to numerous individual papers that analyzed the LHC collisions and determined that the Higgs impostor theories are basically dead. No one can emulate Higgs so accurately. So an important conclusion from the LHC experiments – that represent dozens of hours spent by hundreds of members of the ATLAS and CMS collaborations since 2011 or 2012 – is that
The Higgs Boson Found at the Large Hadron Collider Almost Certainly Cannot Be an ‘Impostor’
Now, look at the title in the Motherboard journal again:
Why the Higgs Boson Found at the Large Hadron Collider Could Be an ‘Impostor’
Haven't you seen it somewhere? Yes, this title is basically exactly the converse of an important truth. It is not just a falsehood. It is a falsehood that tries to push the readers away from a proposition that is not only true but also important, a proposition that actually represents the results of lots of work that has taken place at the LHC.

Is it OK to write such falsehoods? Why has it happened?

Dr Usha Mallik, the Iowa professor, is working on a sub-detector that should be inserted somewhere to the LHC by 2023. This sub-detector could increase the abilities to detect pairs of bottom quarks which is hard, as I will mention in a minute again. And if the measurements of these decays of the Higgs to bottom quark pairs deviates from the Standard Model, and it is a big if, it could be evidence in favor of an impostor theory. But again, even if she succeeds, it's rather likely that the data will be compatible with the Standard Model just like the data collected with the existing detectors so far.

The fake news title may be "justified" as a shortcut for a more honest title such as
a female experimenter in Iowa is working on some sub-detector that will almost certainly find nothing new even after 2023 when it's installed but the work is justified by the observation that if it could find some deviation from the Standard Model, it would be evidence in favor of a Higgs impostor theory, a type of theories that seem almost dead by now, however.
In other words, a lady is doing some boring stuff that won't lead anywhere. This summary doesn't sound so sexy so they have improved it and basically claimed that the Higgs that has been discovered "could" be an impostor even though the actual evidence that has been collected seems to imply exactly the opposite – that it cannot be an impostor, at least not a generic one.

Let me mention that the Higgs boson is predicted to decay to\[

h \to b\bar b

\] the pair of the bottom quark and its antiparticle in a percentage of cases. However, pairs of bottom quarks are created not only from decaying Higgs bosons but also from the "unavoidable QCD mess" at the LHC – which collides protons i.e. hadrons, messy QCD bound states. You may read about this decay channel e.g. in this CERN Courier article. The observation of the direct decay to the bottom quark-antiquark pair is hard. However, there exists a more complicated process:

It's called the vector-boson fusion, or VBF.

Two quarks from the two colliding protons emit two massive electroweak gauge bosons (W-bosons or Z-bosons) that get merged into a Higgs boson, and that Higgs boson decays to the bottom quark-antiquark pair. What is nice about this Feynman diagram is that the final bottom quarks (the middle right part of the diagram) aren't directly connected to the quarks and gluons inside the LHC protons through quark and gluon (i.e. strongly interacting) propagators.

Instead, these bottom propagators are only connected to the quarks from protons by electroweak propagators – by the Higgs and the electroweak spin-one bosons. This fact makes the central portion of the Feynman diagram clean – liberated from the pollution by the messy QCD effect. Consequently, the complicated QCD effects don't contribute so much to the background and the signal may be rather easily separated from the background. And the data already collected at the LHC are already extensive enough to bring us statistically significant evidence that the process depicted by the diagram is taking place.

The result is almost the same: when the signal is found, the interaction of the Higgs boson to the two bottoms is demonstrated. I discussed VBF in order to show that even if Usha Mallik succeeded in measuring the bottom quark decays of the Higgs using a new sub-detector, it probably wouldn't be a qualitatively new discovery that would bring the theorists new information about an interaction between elementary particles. The \(hb\bar b\) interaction may be probed differently, without the sub-detectors.

Experimental particle physicists have a rather hard job. Even relatively modest, technical advances that almost certainly won't "shift the paradigm" require years of work and sometimes billions of dollars. Even if it were discovered that the Higgs found in 2012 is an impostor, it would be something that 99.9999% of the mankind doesn't care about. For particle physicists, it could be a revolution. But this revolution is very unlikely to take place and it is arguably even less likely to take place because of Usha Mallik's work.

I know that these summaries don't sound as attractive as overhyped titles and they may be a worse starting point for Usha Mallik to get new grants etc. However, what I say is far more true and honest than what the Motherboard wrote.

It has unfortunately become a standard policy to write falsehoods and lies as titles of article and even grant applications and it's not just the very nasty people known as the journalists who are responsible for that. The scientists sometimes encourage such falsehoods themselves – and they often benefit from these lies even more than the journalists do. The ethical standards have dropped sufficiently so that Usha Mallik and others think that "it's just OK to write any lie with keywords related to my research" when her work is being described by the media. Sorry but it is not fine.

I have already mentioned that most of Lisa's followers don't have a clue. But it was one physics PhD student whose cluelessness was more visible:

He was clearly trying to chastise Lisa as if he were some moral authority. What the hell are you talking about, Christopher? Lisa hasn't tweeted any argument. She just made an observation that an article with a title that seems false to her – and to me and, more importantly, to most particle physicists, too – was published in a magazine.

The phrase "fake news" has been fashionable for several months. It's been used by the anti-Trump leftist media and it was often used inadequately. Many things labeled as "fake news" weren't fake at all – and on the contrary, it was many articles about "fake news" and especially about the origin of these alleged "fake news" (especially when the origin was claimed to be in Moscow) that were the actual "fake news".

One may say that the term "fake news" has backfired. It's been used against those who had used it for the first time. There have been various social processes like that. But at the end, "fake news" is just a currently fashionable synonym for an "untrue article in the media". There have always been untrue articles in the media and we always needed to use some words to describe "untrue articles in the media". The term "fake news" does a better job than others – it's catchy and concise enough – and it's plausible that its lifetime will be longer than we might think.

Even if she hasn't posted any long blog post substantiating her views, there is nothing "unethical" about Lisa's usage of the term "fake news" for something that she considers a falsehood published by the media. Christopher, if you think that "ethics" means the rules to avoid several phases that you have arbitrarily declared as taboos, such as the phrase "fake news", then your ethics isn't worth much.

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