Tuesday, April 26, 2011

D0 reports a new 3 sigma bump with mass around 325 GeV

It seems that experimentalists have gone totally crazy. Maybe new physics is indeed emerging from LHC and they want to publish every data bit in the hope of getting paid visit to Stockholm. CDF and ATLAS have told about bumps and now Lubos tells about a new 3 sigma bump reported by D0 collaboration at mass 325 GeV producing muon in its decay producing W boson plus jets. The proposed identification of bump is in terms of decay of t' quark producing W boson.

Lubos mentions also second mysterious bump at 324.8 GeV or 325.0 GeV reported by CDF collaboration and discussed by Tommaso Dorigo towards the end of the last year. The decays of these particles produce 4 muons through the decays of two Z bosons to two muons. What is peculiar is that two mass values differing by .2 GeV are reported. The proposed explanation is in terms of Higgs decaying to two Z bosons. TGD based view about new physics suggests strongly that the three of four particles forming a multiplet is in question.

One can consider several explanations in TGD framework without forgetting that these bumps very probably disappear. Consider first the D0 anomaly alone.

  1. TGD predicts also higher generations but there is a nice argument based on conformal invariance and saying that higher particle families are heavy. What "heavy" means is not clear. It could of mean heavier that intermediate gauge boson mass scale. This explanation does not look convincing to me.
  2. Another interpretation would be in terms of scaled up variant of top quark. The mass of top is around 170 GeV and p-adic length scale hypothesis would predict that the mass should equal to a multiple of half octave of top quark mass. Single octave would give mass of 340 GeV. The deviation from predicted mass would be 5 per cent. This quark could correspond to t quark of scaled up hadron physics predicted by TGD and discussed in previous postings (see this, this, abd this).
The prediction of the scaled up hadron physics allows to ask whether a common explanation for all these particles as decay products of kaons of M89 hadron physics could exist. Could charged kaon produceneutral pion and single W boson and therefore muon just as the 300 GeV charged pion would produce W boson plus neutral pion decaying to two jets. This explanation excludes the the interpretation of ATLAS bump as neutral pion and CDF bump as charged kaon but CDF and D0 bumps could live peacefully together.

If there indeed are two slightly different masses one can can ask whether the two different masses could be due to CP breaking. The mass difference between short-lived and long-lived ordinary kaon is however extremely small- 3.5×10-12 MeV- and scaling by a factor 512 would give quite too small mass difference. That CP (or even CPT) breaking should be so large for the scaled up version of hadron physics looks odd. As a matter fact, the splitting is of the same order as electromagnetic splitting between mesons with different charges obtained by scaling with factor 512 from the mass splitting of order 1 MeV for ordinary mesons.

Addition: The newest rumor is that ATLAS rumor about too photo-philic Higgs with exactly the same mass of 115 GeV as the hegemony wanted it to have was not more than a rumor. Sorry Lubos;-).

For me the newest rumor is a relief since it makes it more easier to find room for the remaining rumors in zoomed up hadron physics. The CDF rumor about 145 GeV bump would be interpreted in terms of charged pion. The latest D0 rumor weighting 325 GeV and producing W bosons, and the earlier CDF rumor having two slightly different masses around 325 GeV and producing two Z bosons would in turn be interpreted in terms of scaled up charged and neutral kaons.

However, if a strict scaling would hold true for the meson masses, one could conclude that either 145 GeV or 325 rumour is only a humor since the mass scale ratio 325/145 ≈ 2.24 is smaller than the mass scale ratio for ordinary kaon and pion about 490/140≈ 3.5. This would leave only one or two rumors to be killed. Probably they suffer a natural death within week or two in any case. I have not taken main stream theorists seriously for decades but believed that experimentalists are somehow more rooted in reality. Has the hype disease infected also experimentalists? This would be sad. Addition: The latest rumor about Atlas by Peter Woit tells that New Science has received inner information that ATLAS bump has not been found in other experiments. Tommaso in turn claims that this cannot be true! From which some reader concludes between lines that ATLAS has observed photo-philic Higgs after all!! When physics blogs came, I thought that they would provide forums for a genuine discussion about new ideas and could also serve some kind of educational function: for instance, about statistical methods of particle physics. I was wrong: they are forums for a chat about what names have said, for boosting the ego of the blogger, for the endlessly boring n sigma talk, and speculations around rumors and counter rumors. Does the situation in the web of so called respected blogs reflect the situation also in experimental particle physics? I sincerely hope that this is not the case.


Ulla said...

The fact that technicolor figure again tells very well how desperate the situation is?

Can you tell something about the mass differences between a charged and a neutral pion or kaon. How is it calculated or measured? I guess the charged one must be heavier?

Matti Pitkänen said...

The order of magnitude for electromagnetic mass differences can be understood and are about 4 MeV for pion. Same order of magnitude for kaon but opposite sign. I have the feeling that the precise understanding was not very good when I last time was interested about mass differences.

Masses can be determined quite precisely experimentally (five digit accuracy for kaon) and the history of how mass measurements and related data processing have evolved would be fascinating to read.

I remember the student days when students were analyzing manually the spiral tracks of charged particles in magnetic field appearing in bubble chamber pictures. Nowadays everything is computerized.

I do not have overall view about the experimental methods in my spine to give a lecture about the topic without preparation;-).

The estimation of mass differences theoretically requires wave functions of quark and antiquark in meson. One can understand qualitatively why neutral pion is lighter than charged one due to Coulomb attraction between quark and antiquark. Also for kaon one can understand qualitatively why neutral kaon is heavier.

Quantum mechanics is essential for gaining the understanding: in neutral pion one has quantum superposition of uubar pari and ddbar pair making no sense classically.

Matti Pitkänen said...

Still a general comment about experimental mass determination. Masses of sufficiently stable particles like electron, muon, proton, neutron, ... can be determined from their behavior in electromagnetic fields.

For short-lived particles the mass determination involves much more theory. Typically one identifies the decay products of a resonance and uses conservation laws for momentum and energy to deduce the mass of the resonance. Special relativistic formulas are in central role so that anyone claiming that Einstein was deadly wrong has to revise the entire particle physics from top to bottom-quite a job;-). The peak of the mass value distribution for the bump defines what is called the mass of the resonance.

In the case of neutrinos one must use energy and momentum conservation to deduce the four-momentum of neutrino as missing energy and momentum. Neutrino masses are poorly known and TGD suggests that they appear in several p-adic mass scales. This would explain the claimed CPT breaking as apparent.

In the case of light quarks the situation is even more theory laden since they cannot be observed directly. Top quark as the heaviest quark is exceptionally simple. Large number of experimental data is used to deduce the optimal estimate for the light quark masses and lattice QCD is also involved. For light quarks the situation is made complex also by the fact that there are two notions of mass: current quark mass which is of order 10 MeV for u and d and constituent quark mass which is by order of magnitude higher.

TGD suggests that constituent quarks correspond to valence quarks having higher mass scale than current quarks identifiable as sea quarks. Higher mass scale would be due to a shorter p-adic length. Sea quarks could be perhaps assigned with the color magnetic body of hadron having much larger size than hadron itself. It could be also that part of the time valence quarks are in various mass states corresponding to different octaves of the basic mass: just like the note from music instruments involves superposition of octaves (besides harmonics).

The simple analysis of bubble chamber pictures has transformed to an extremely complex data processing. Signal to noise ratio is extremely small and the amount of data processed incredibly large. The need to process effectively this data led to the discovery of web.

Among other things, one needs a Monte Carlo simulation of standard model defining the hay stack. The signatures of new physics are needles but unfortunately it is difficult to distinguish them from hays. Standard model predicts the probability distribution for various degree sof needle-ness for hays. if the probability of the hey to look like needle is very small and one still sees the needle, one can conclude that a real needle was there. If the needle was there at 5 sigma level, Nobel committee can conclude that the experimenter has discovered a needle. If several groups have lost and found their needles, a bloody fight for priorities begins and needles find better use than to be lost in haystacks.