AMS results as a support for lepto-hadron physics and M89 hadron physics?
The results of AMS-02 experiment are published. There is paper, live blog from CERN, and article in Economist. There is also press release from CERN. Also Lubos has written a summary from the point of view of SUSY fan who wants to see the findings as support for the discovery of SUSY neutralino. More balanced and somewhat skeptic representations paying attention to the hypeish features of the announcement come from Jester and Matt Strassler.
The abstract of the article is here.
A precision measurement by the Alpha Magnetic Spectrometer on the International Space Station of the positron fraction in primary cosmic rays in the energy range from 0.5 to 350 GeV based on 6.8 × 106 positron and electron events is presented. The very accurate data show that the positron fraction is steadily increasing from 10 to 250 GeV, but, from 20 to 250 GeV, the slope decreases by an order of magnitude. The positron fraction spectrum shows no fine structure, and the positron to electron ratio shows no observable anisotropy. Together, these features show the existence of new physical phenomena.
New physics has been observed. The findings confirm the earlier findings of Fermi and Pamela also showing positron excess. The experimenters do not give data above 350 GeV but say that the flux of electrons does not change. The press release states that the data are consistent with dark matter particles annihilating to positron pairs. For instance, the flux of the particles is same everywhere, which does not favor supernovae in galactic plane as source of electron positron pairs. According to the press release, AMS should be able to tell within forthcoming months whether dark matter or something else is in question.
About the neutralino interpretation
Lubos trusts on his mirror neurons and deduces from the body language of Samuel Ting that the flux drops abruptly above 350 GeV as neutralino interpretation predicts.
- The neutralino interpretation assumes that the positron pairs result in the decays χχ→ e+e- and predicts a sharp cutoff above mass scale of neutralino due to the reduction of the cosmic temperature below critical value determined by the mass of the neutralino leading to the annilation of neutralinos (fermions). Not all neutralinos annhilate and this would give to dark matter as a cosmic relic.
- According the press release and according to the figure 5 of the article the positron fraction settles to small but constant fraction before 350 GeV. The dream of Lubos is that abrupt cutoff takes place above 350 GeV: about this region we did not learn anything yet because the measurement uncertainties are too high. From Lubos's dream I would intuit that neutralino mass should be of the order 350 GeV. The electron/positron flux is fitted as a sum of diffuse background proportional to Ce+/-E-γe+/- and a contribution resulting from decays and parametrized as Cs E-γs exp(-E/Es) - same for electron and positron. The cutoff Es of order Es= 700 GeV: error bars are rather large. The factor exp(-E/Es) does not vary too much in the range 1-350 GeV so that the exponential is probably motivated by the possible interpretation as neutralino for which sharp cutoff is expected. The mass of neutralino should be of order Es. The positron fraction represented in figure 5 of the article seems to approach constant near 350 GeV. The weight of the common source is only 1 per cent of the diffuse electron flux.
- Lubos notices that in neutralino scenario also a new interaction mediated by a particle with mass of order 1 GeV is needed to explain the decrease of the positron fraction above 1 GeV. It would seem that Lubos is trying to force right leg to the shoe of the left leg. Maybe one could understand the low end of the spectrum solely in terms of particle or particles with mass of order 10 GeV and the upper end of the spectrum in terms of particles of M89 hadron physics.
- Jester lists several counter arguments against the interpretation of the observations in terms of dark matter. The needed annihilation cross section must be two orders of magnitude higher than required for the dark matter to be a cosmic thermal relic -this holds true also for the neutralino scenario. Second problem is that the annihilation of neutralinos to quark pairs predicts also antiproton excess, which has not been observed. One must tailor the couplings so that they favor leptons. It has been also argued that pulsars could explain the positron excess: the recent finding is that the flux is same from all directions.
What could TGD interpretation be?
What can one say about the results in TGD framework? The first idea that comes to mind is that electron-positron pairs result from single particle annihilations but it seems that this option is not realistic. Fermion-antifermion annihilations are more natural and brings in strong analogy with neutralinos, which would give rise to dark matter as a remnant remaining after annihilation in cold dark matter scenario. An analogous scenario is obtained in TGD Universe by replacing neutralinos with baryons of some dark and scaled up variant of ordinary hadron physics of leptohadron physics.
- The positron fraction increases from 10 to 250 GeV with its slope decreasing between 20 GeV and 250 GeV by an order of magnitude. The observations suggest to my innocent mind a scale of order 10 GeV. The TGD inspired model for already forgotten CDF anomaly discussed in the chapter The recent status of leptohadron hypothesis of "p-Adic length Scale Hypothesis and Dark Matter Hierarchy" suggests the existence of τ pions with masses coming as three first octaves of the basic mass which is two times the mass of τ lepton. I have proposed interpretation of the positron excess ob served by Fermi and Pamela now confirmed by AMS in terms τ pions. The predicted mass of the three octaves of τ pion would be 3.6 GeV, 7.2 GeV, and 14.4 GeV. Could the octaves of τ pion explain the increase of the production rate up to 20 GeV and its gradual drop after that?
There is a severe objection against this idea. The energy distribution of τ pions dictates the width of the energy interval in which their decays contribute to the electron spectrum and what suggests itself is that decays of τ pions yield almost monochromatic peaks rather than the observed continuum extending to high energies. Any resonance should yield similar distribution and this suggests that the electron positron pairs must be produced in the two particle annihilations of some particles.
The annihilations of colored τ leptons and their antiparticles could however contribute to the spectrum of electron-positron pairs. Also the leptonic analogs of baryons could annihilate with their antiparticles to lepton pairs. For these two options the dark particles would be fermions as also neutralino is.
- Could colored τ leptons and - hadrons and their muonic and electronic counterparts be really dark matter? The particle might be dark matter in TGD sense - that is particle with a non-standard value of effective Planck constant hbareff coming as integer multiple of hbar. The existence of colored excitations of leptons and pion like states with mass in good approximation twice the mass of lepton leads to difficulties with the decay widths of W and Z unless the colored leptons have non-standard value of effective Planck constant and therefore lack direct couplings to W and Z.
A more general hypothesis would be that the hadrons of all scaled up variant of QCD like world (leptohadron physics and scaled variants of hadron physics) predicted by TGD correspond to non-standard value of effective Planck constant and dark matter in TGD sense. This would mean that these new scaled up hadron physics would couple only very weakly to the standard physics.
- At the high energy end of the spectrum M89 hadron physics would be naturally involved and also now the hadrons could be dark in TGD sense. Es might be interpreted as temperature, which is in the energy range assigned to M89 hadron physics and correspond to a mass of some M89 hadron. Fermions are natural candidates and the annihilations nucleons and anti-nucleons of M89 hadron physics could contribute to the spectrum of leptons at higher energies. The direct scaling of M89 proton mass gives mass of order 500 GeV and this value is consistent with the limits 480 GeV and 1760 GeV for Es.
- There could be also a relation to the observations of Fermi suggesting an annihilation of some bosonic states to gamma pairs with gamma energy around 135 GeV could be interpreted in terms of annihilations of a M89 pion with mass of 270 GeV (maybe octave of leptopion with mass 135 Gev in turn octave of pion with mass 67.5 GeV).
How to resolve the objections against dark matter as thermal relic?
The basic objection against dark matter scenarios is that dark matter particles as thermal relics annihilate also to quark pairs so that proton excess should be also observed. TGD based vision could also circumvent this objection.
- Cosmic evolution would be a sequence of phase transitions between hadron physics characterized by Mersenne primes. The lowest Mersenne primes are M2=3, M3=7, M5=31, M_7=127, M13, M17, M19, M31, M61, M89, and M107 assignable to the ordinary hadron physics are involved but it might be possible to have also M127(electrohadrons). There are also Gaussian Mersenne primes MG,n= (1+i)n-1. Those labelled by n=151,157,163,167 and spanning p-adic length scales in biologically relevant length scales 10 nm,..., 2.5 μm.
- The key point is that at given period characterised by M_n the hadrons characterized by larger Mersenne primes would be absent. In particular, before the period of the ordinary hadrons only M89 hadrons were present and decayed to ordinary hadrons. Therefore no antiproton excess is expected - at least by the mechanism producing it in the standard dark matter scenarios where all dark and ordinary particles are present simultaneously.
- The second objection relates to the cross section, which must be two orders of magnitude larger than required by the cold dark matter scenarios. I am unable to say anything definite about this. The fact that both M89 hadrons and colored leptons are strongly interacting would increase corresponding annilation cross section and leptohadrons could later decay to ordinary leptons.
Connection with strange cosmic ray events and strange observations at RHIC and LHC
The model could also allow to understand the strange ultrahigh energy cosmic ray events (Centauros,etc) suggesting a formation of a blob ("hot spot" of exotic matter in atmosphere and decaying to ordinary hadrons. In the center of mass system of atmospheric particle and incoming cosmic ray cm energies are indeed of order M89 mass scale. As suggested, these hot spots would be hot in p-adic sense and correspond to p-adic temperature assignable to M89. Also the strange events observed already at RHIC in heavy ion collisions and later at LHC in proton-heavy ion collisions, and in conflict with the perturbative QCD predicting the formation of quark gluon plasma could be understood as a formation of M89 hot spots (see this). The basic finding was that there were strong correlations: two particles tended to move either parallel or antiparallel, as if they had resulted in a decay of string like objects. The AdS/CFT inspired explanation was in terms of higher dimensional blackholes. TGD explanation is more prosaic: string like objects (color magnetic flux tubes) dominating the low energy limit of M89 hadron physics were created.
The question whether M89 hadrons, or their cosmic relics are dark in TGD sense remains open. In the case of colored variants of the ordinary leptons the decay widths of weak bosons force this. It however seems that a coherent story about the physics in TGD Universe is developing as more data emerges. This story is bound to remain to qualitative description: quantitative approach would require a lot of collective theoretical work.
Also CDMS claims dark matter
Also CDMS (Cryogenic Dark Matter Search) reports new indications for dark matter particles: see the Nature blog article Another dark matter sign from a Minnesota mine. Experimenters have observed 3 events with expected background of .7 events and claim that the mass of the dark matter particle is 8.6 GeV. This mass is much lighter than what has been expected: something above 350 GeV was suggested as explanation of the AMS observations. The low mass is however consistent with the identification as first octave of tau-pion with mass about 7.2 GeV for which already forgotten CDF anomaly provided support for years ago (as explained above p-adic length scale hypothesis allows octaves of the basic mass for leptopion which is in good approximation 2 times the mass of the charged lepton, that is 3.6 GeV). The particle must be dark in TGD sense, in other words it must have non-standard value of effective Planck constant. Otherwise it would contribute to the decay widths of W and Z.