Thursday, March 14, 2013

God particle's humility on display it turns on two light bulbs less often than expected...

OK, I was inspired by this title of an article about Pope Francis. But you should have no doubts about it: the Higgs boson is even more humble and obedient than the Indian-born Argentinian chemist and the son of a railway worker who was just chosen as the new Bishop of Rome by puppets of Hugo Chavez who controlled the job contest from Hell.

What I want to say is that the anomalously high chance that the \(126\GeV\) Higgs boson splits into two photons, \(h\to\gamma\gamma\), is no longer anomalously high. ATLAS and CMS used to suggest that the rate could be up to \(1.8\) times the Standard Model prediction. However, ATLAS updated the figure to something like \(1.5\pm 0.3\) (which is pretty much one) a week ago and today, CMS updated its results and the new value is even lower than expected, \(0.8\pm 0.3\). Calculate the ATLAS+CMS average and you will find out that the decay rate is what it should be within less than one sigma.

Lots of experimental LHC papers were recently published that demonstrate that all measurable properties of the Higgs boson agree with the Standard Model within the error margin that is getting smaller. Of course that the agreement won't be quite perfect but the deviation may turn out to be much lower than what the LHC may resolve today.

Many phenomenology papers were written in the recent year that were inspired by the possibility that the diphoton rate is higher than it is in the Standard Model. The announcement today shows how shaky such a motivation usually is. You may be attracted by 2-sigma bumps if you don't see any excesses that are more significant. But chances are very high that even this only excess above the simplest theory that you observe is just a fluke. It was almost certainly the case of the Higgs diphoton branching ratio, too.

Experimental anomalies are usually flimsy foundations for new theories, especially if their statistical significance is unimpressive. Only robust top-down arguments represent a reliably solid foundation to construct theories of physics, both at high energies and the effective ones. In other words, all good fundamental physics should start and end with string theory. Crackpots will never understand this point but it's not my fault.

There's no longer any anomaly suggested by the experiments in the behavior of the Higgs boson that would deserve attention and I personally guess that new physics will be first observed via a new particle, not an anomalous property of the Higgs boson (I can't promise you any deadline, however).

Today, the media are full of the stories that now the LHC physicists really think that what they found is the Higgs boson. Even the Drudge Report has the God particle as the "story of the day". Spin-two, pseudoscalar, and other bizarre alternatives and impostors have been pretty much ruled out. But it's extremely excessive to suggest that something qualitative has changed this week. Those theories have been de facto dead for half a year.

There are lots of papers presented at the Moriond 2013 conference that I could talk about – papers with results compatible with the Standard Model. I find these things boring given their null contents. But let me mention one paper that at least has some history. In June 2011, Tommaso Dorigo hyped a very bad measurement by CDF at the Tevatron that claimed that the top-antitop mass difference (which must be zero due to the CPT-theorem i.e. essentially due to the Lorentz symmetry, of course) was \[

(3.3\pm 1.4_{\rm stat}\pm 1.0_{\rm syst})\GeV.

\] Their U.S. colleagues in the D0 collaboration debunked that preposterous result. But it's interesting to see what CMS may determine with the 2012 data. Their value of the top-antitop mass difference is \[

(0.27\pm 0.20_{\rm stat}\pm 0.12_{\rm syst})\GeV.

\] That's compatible with zero, of course. Note that both the mean value as well the error margins shrank by roughly one order of magnitude! This is the progress in the experimental reach and precision that we witnessed in less than two years.

Incidentally, over 16,000 people are subscribed to this blog either via iGoogle or Google Reader. The latter service will cease to exist after July 1st, 2013. I encourage everyone who is actively using Google Reader to test alternatives such as Netvibes, Feedly, and NewsBlur.


  1. 16,000! I had no idea you had so many readers.

  2. Today is a major Triple Witching Day, Lubos:

    * 3-14 Pi Day 3.14

    * Albert Einstein's Birthday

    * The Higgs-Boson is confirmed by CERN

  3. The readers who actually end up reading or at least opening this or another blog entry is way smaller, a few thousand at most. This feed reduction is still modest relatively to the Twitter reduction. Tens of thousands of followers may lead to virtually no hits to the page if the tweet contains its URL.

  4. I thought "triple witching" is only used in financial markets. Let me count as unimpressed by all these things.

    3-14 is really a silly numerology that someone talks about but almost every other day could be discussed in this way. 6-18 could be the golden mean day, 2-17 could be the e-day, then you have all the 11-11 and 12-12 and 2-22 periodic day. Let me stop. Those agreements are coincidental and the probability of match is high, anyway.

    Einstein has birthday every year and given the fact that he's not the only physicist, the birthdays of physicists, even very important ones, appear every couple of day, too. Moreover, the 3-14 and Einstein day aren't independent because they always occur on the same day.

    The "confirmation of the Higgs today" is a silly game for the media and their stupid readers.

  5. I totally agree with you.

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  6. Hm, Clifford Johnson calls it Pi-day too:

    But I am not impressed by numerology and about what is written of said in the mass media I give a damn since quite a long time ago now . :-P

  7. Wow. Congratulations Lubos. Your blog is fantastic, never ever boring, always exciting and soooo intelligent ! Thank you for sharing your exceptional -and unique- brain with us.

  8. Oh dear, if the di-photon excess is gone that's it, the game's up. There's NOTHING else there.

  9. Come on, that's silly. You're presenting this diphoton hype as if it has been the particle physics' only hope.

  10. I know where you heve these words from, James ;-P

    Reading sourball sites and adopting their attitude is not a healthy way of living ;-)...

  11. "and end with string theory", so true...

  12. I think this guy saw those last two lightbulbs: