Saturday, July 14, 2012

Is it really Higgs?

The attitudes to the discovery are becoming more and more realistic and it is indeed transforming from "Higgs discovery" to "discovery". I of course feel empathy for those who have spent their professional career by doing calculations with Higgs: it is not pleasant to find that something totally different might be in question. Even laymen are probably realizing that that 125 GeV mass is not a prediction of string theories or standard SUSY: string theorists have successfully predicted all the masses of Higgs candidates that have appeared during last years(at least 165 GeV, 115 GeV, 1145 GeV, and 125 GeV) but always only after the rumor. Usually this is called post-diction, not a prediction. In the latest New Scientist the problems are acknowledged and summarized: congratulations for New Scientist.

For most decay channels the rates differ from standard model predictions considerably (see this). In particular, gamma gamma decay rate is about three times too high and tau lepton pairs are not produced at all. This is very very alarming since Higgs should couple to leptons with coupling proportional to its mass.

It is becoming clear that it is not standard model Higgs. People have begun to talk about "Higgs like" state since nothing else they do not have because technicolor scenario is experimentally excluded.

SUSY enthusiasts claim that it is SUSY Higgs but there are no indications for SUSY. Lubos is getting desperate and is already claiming experimentalists for in-honesty in the interpretation of data! Lubos has got also irritated about certain bloggers who refuse to admit that the new particle is there. I have not seen any blogger refusing to admit that it is not here. Maybe Lubos meant that the bloggers in question are not convinced about the Higgsy character of the new particle but failed to distinguish between "Higgs" and "spinless particle" as so many times earlier. I do not even dare to imagine that it is me who should be blamed for the irritated mood of Lubos since at least officially Lubos has not shown any signal of being aware of my humble blog existence (behaving just as a brahmin of science is expected to behave towards the pariah class);-).

The most natural - albeit not the only possible - TGD identification is as a pion-like state. This would mean that it is pseudo-scalar: also SUSY predicts pseudo-scalar as one of the several Higgses.

The basic predictions of TGD scenario deserve to be summarized.

  1. Also two charged and one neutral companion of pseudoscalar should exist. This is because pseudoscalar is for expected to be replaced by imbedding space vector having only CP2 components (4) forming electroweak triplet and singled just as ew gauge bosons do. But what authority could force the experimentalists to search for the decays of this kind of states?

  2. ATLAS and CMS see their Higgs candidates at slightly different masses: mass difference is about 1 GeV. Could this mean that the predicted two neutral states contribute and have been already observed! This could also explain the too large decay rate to two gammas (WW decay rate would be more or less same as for standard model and only the second neutral state would contribute to it).

    One can however counter-argue that ordinary pion has no neutral companion of same mass. In hadronic sigma model it has scalar companion with which it forms 1+3 multiplet of SO(4), the tangent space group of CP2 reducing to SU(2)L×U(1) identifiable as U(2) ⊂ SU(3) in the concrete representaton of pion states. Could one think that this is the case also now and sigma develops vacuum expectation analogous to that of Higgs determining most of the couplings just as in sigma model for ordinary hadrons? The problem is that the neutral component should be scalar.

    Could one get rid of the additional sigma state? CP2 allows two geodesic spheres and the second one is homologically non-trivial allowing SO(3) as isometries instead of U(2). In this case one would have naturally SO(3) triplet instead of 3+1 and no sigma boson. For the four kaon like state one would have 3+1 naturally. As proposed in an earlier posting this could distinguish between pion-like and kaon-like multiplets. What is genuinely new that strong isospin groups U(2) and SO(3) would reduce to subgroups of color group in spinor representation.

  3. If there is pion-like state there, it is pseudo-scalar: this might become clear during this year. SUSY people would identify it as one of the SUSY Higgses.

  4. Pion-like states consist of "scaled up" quarks of M89 hadron physics and they prefer to decay to hadrons. Lepton pairs are produced only in higher order via box diagrams with W pair as vertical sides and quark line and lepton line as horizontal sides. This explains why tau pairs are not observed. This is very important point.

    The fastest decays could take place to two gluons of M89 hadron physics transforming to ordinary gluons in turn decaying to quarks and producing jets.

  5. The simplest option is that effective action for decays to weak gauge bosons is instanton action assignable to axial current anomaly. WW production rate is consistent with standard Higgs and this fixes the coefficient of the instanton term if one assumes that electroweak symmetry is not broken so that γ, Z, and W would have different coefficients. I would be happy if I had a graduate student as a slave doing the calculations.

  6. Associated production of bbar +W has been observed as predicted. In TGD bbar would correspond to decay to two gluons annihilating to quark pair. Light quark pairs would be produced much more than in Higgs decays where Higgs-quark coupling is proportional to quark mass. But again: who would force experimenters to search for such non-Higgsian signatures since for Higgs the rates would be quite to slow.

What experimenters have to say about these predictions after year is interesting. The discovery of charged partners would destroy the Higgs interpretation. My meager and perhaps too optimistic hope is that they could be discovered by accident.


Leo Vuyk said...

“The beginning of the end of the standard model ”
NewScientist: 11 july 2012 about deviant decays.

“Many of my colleagues and I think that this discovery on Wednesday may mark the beginning of the end of the standard model,” says Georg Weiglein of the German Electron Synchotron research centre (DESY) in Hamburg. “Maybe these little deviations from the standard model really build up to a significant deviation. Maybe once we make this more precise with more data we will see that this is not the standard-model Higgs.”

Ervin Goldfain said...

Even if the signal is confirmed to represent the SM Higgs, too many theorists forget that the Higgs boson adds a large number of theoretical puzzles that are still open.

Ulla said...

When you’re searching for elusive manifestations of new physics, it’s easy to be fooled by statistical fluctuations or instrumental quirks.

"today’s search for the Higgs boson, the only remaining undiscovered fundamental particle required by particle theory’s standard model (see PHYSICS TODAY, February 2012, page 16).

Because the Higgs search involves a signal-to-background ratio of order 10^-10, sophisticated multivariate techniques such as artificial neural networks are needed for finding needle candidates in the
haystack of impostors. And when a possible signal does appear, assessing its statistical significance nowadays requires great care.

The standard model, which took shape in the late 1970s, does not predict a specific mass MH for the
Higgs, but it does predict, as functions of MH, all of its couplings to other particles and therefore its production and decay rates. So non-observations of anticipated decay modes are used to disfavor the existence of the standard-model Higgs in various MH ranges."

Jester said the statistic result was dependent on the too big bumps which doesn't belong to SM.

Many admits today that SM is in danger, because of abnormal decay patterns. And this is also why this research is done. But if they continue with electron collider they must have a hint that the theory is true first. We must just wait and see what they find out. My feelings now is that this will have the same fate as the other bumps. The announcement was more a political one, to get money? Why would Tevatron be one day earlier than LHC otherwise? said...

To Erwin:

This is indeed true. Higgs is not a microscopic theory of massivation. It is just a parametrization in QFT framework. People tend to forget this.

To my view it is not possible to confirm that the particle is standard model Higgs as absolute truth: what can be confirmed is that Higgs allows to fit the data, nothing more.

I have mentioned the problem with electron collider which has been planned for years. If it is not Higgs but - as I hope- pion like state of new hadron physics, the next collider will be bigger version of LHC. A lot of plans go to paper basket.

Ulla said...

Another decay deviation 'too large to fit the SM'.

Ulla said...

Wikipedia added now the Higgs boson as scalar. This is the same as accepting the holographic principle?

Have you seen this?

measuring the spin susceptibility in a repulsive fermionic gas where there is a population imbalance (a difference between spin-up and spin-down atoms) could provide convincing evidence of novel magnetic phases,

Ulla said...