Refined Higgs Rumours

13 December: please follow the live blog for up-to-date news

Jester has kindly provided some more refined rumours to give us something to talk about and make the time go quickly while we wait for the Big Event. Here are my comments

“The Standard Model Higgs boson is excluded down to approximately 130 GeV, but not below.”

Very nice but this will be using the WW channel. I don’t fully trust this decay mode for exclusions in the lower energy range because of the poor energy resolution. Previously we have seen both exclusions and excesses near this region. It could mean that there is a non-standard Higgs Boson at 140 GeV that might appear to have lower signal because e.g. it decays to something unknown. It could also just be an effect of the poor WW resolution. I will be looking to see what happens at the 140 GeV point in the combined diphoton and ZZ -> 4l channel without WW  to understand this better.

“As already reported widely on blogs, both experiments have an excess of events consistent with the Higgs particle of mass around 125 GeV.”

The interesting thing here is going to be to see how big the excess is when the two experiments are combined. Combining the excess strengths is not just a matter of adding in quadrature. That gives just a crude approximation. I will do a better approximation when I have the data. I am also wondering whether the size of the signal is consistent with a Standard Higgs or bigger. I think it has to be bigger by a factor of two because we only expect 2-sigma significance without the WW channel. I will also look forward to seeing how this shows up on the raw event count plots. Overall a lot of what is seen here will be noise because the sensitivity is still relatively low, but a high sigma combined excess would mean there is probably something.

“The excess is larger at ATLAS, where it is driven by the H→γγ channel, and supported by 3 events reconstructed in the H→ZZ*→4l channel at that mass. The combined significance is around 3 sigma, the precise number depending on statistical methods used, in particular on how one includes the look-elsewhere-effect.”

How close in energy are these three events? That could be key. In any case we should not expect much contribution from ZZ at 125 GeV yet. The channel is just not sensitive enough with 10/fb and will be mostly weighted out in the combination with diphoton.

“CMS has a smaller excess at 125 GeV, mainly in the H→γγ channel, but their excess in H→4l is oddly shifted to somewhat lower masses of order 119 GeV. All in all, the significance at 125 GeV in CMS is only around 2 sigma.”

No surprise that the CMS ZZ result is inconsistent. There is too much noise in this channel at < 130 GeV to know what is the real signal at this point. At the end of next year it will start to come through. For now it will add just a little contribution to the diphoton channel. 2 sigma is very little but when combined with ATLAS it adds up.

“With some good faith, one could cherish other 2-sigmish bumps in the γγ channel, notably around 140 GeV. Those definitely cannot be the signal of the Standard Model Higgs, but could well be due to Higgs-like particles in various extensions of the Standard Model.”

Indeed, but the big question is whether the 140 GeV bumps previously seen in the ZZ channel are still there. This is now very sensitive at 140 GeV so we should know something. Since there is no rumour about this it might mean that nothing is there and the diphoton bump is just the remainder of the big excess seen there in the summer.

Aside from all that we are interested to see what remains at higher mass, especially around 240 GeV and 600 GeV. Stay tuned.

8 Responses to Refined Higgs Rumours

  1. Kea says:

    A fairy funeral! I will wear summer colours!

  2. Alejandro Rivero says:

    I’d prefer if the results are unconclusive, because I do not see how to fit it in my own schema. But if there is something in the 119-225 GeV area, I must point out that formula (9) in says “122.384 GeV”.

    The origin of this number is a composite model for W and Z, calculated by Hans de Vries in November of 2004 using old relativistic quantum mechanics techniques. The model aim was a prediction of Weinberg angle, but it includes two extra mass predictions that happen to be in 176 and 122 GeV.

  3. Leo Vuyk says:

    What if there is no massive Higgs boson?
    Then we need a massless Higgs as the virgin mother particle which is able to transform into other particles like the electron and positron. and photons like a graviton.

    We also need an adapted standard model see:

    In particle physics it seems to me an interesting challenge to postulate that the FORM and structure of
    elementary particles is the origin of different FUNCTIONS of these particles.
    In this paper we present a possible solution based on complex 3-D ring shaped particles,
    which are equipped with three point like hinges and one splitting point, all four points divided
    equally over the ring surface.
    The 3-D ring itself is postulated to represent the “Virgin Mother” of all other particles and is
    coined Higgs particle, supplied with the 3-hinges coded (OOO), which gives the particle the
    opportunity to transform after some sort of mechanical collision with other particles into a
    different shape, with a different function.
    Thus in this Quantum Function Follows Form theory, the Higgs is interpreted as a massless
    transformer particle able to create the universe by transform its shape after real mechanical
    collision and merge with other shaped particles into complex and compound knots.

    See perhaps also:

  4. Cliff H says:

    So clearly the standard model couples differently to the CMS versus ATLAS…

  5. Philip Gibbs says:

    Can you give specific examples of people “acting as if the forthcoming LHC data unquestionably heralds the advent of the putative Standard Model Higgs boson” ? Most people seem to realize that the results will be inconclusive and a range of possibilities remain open.

  6. Jonas says:

    Our group was actually watching the seminar today together with Peter Higgs here in Edinburgh. He seemed remarkably unmoved by the results.

    Still this is a great moment for Edinburgh and for particle physics in general. While it is too early to draw definite conclusions most people will agree that the results look very promising..

    • Philip Gibbs says:

      Thanks Jonas, that is good to hear. I recall how laid back he was from when I was there as a postdoc 25 years ago.

      Edinburgh is my home town.

  7. wl59 says:

    Until now, I read and analyzed only the documents today made public by CERN. And on the base just of this, I resumed my opinion in a forum where I often write something:

    To my opinion, according to a health interpretation of these data, there is no Higgs; statistically it’s excluded (95%) within the relevant mass interval. The strongest indications between 110 and 130, by H –> diphoton, are almost opposite for CMS and ATLAS, excluding each one the others ‘best’ interval.

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