Wednesday, September 22, 2010

The News Today

From the CMS experiment, and reported at vixra log and TRF, a stunning new image from the LHC. The report of particle correlations resembling quark gluon plasma results is here. On the CMS seminar slides by Roland, we have a comparison of the short range correlations with Monte Carlo simulations, showing an effective cluster size of $K$ particles for the minimum bias results. The open circles and squares are simulation and the red dots are CMS results. The interesting high multiplicity events have long range (near side) correlations that peak in the transverse momentum range of $1$ to $3$ GeV$/c^2$. The important plot, that shows the effect after a high multiplicity trigger is applied:


  1. A number of people have already been heard to say that the long range correlations clearly indicate a string like extended object ... please people, give yourselves a little more time to analyse what is clearly a complex experiment. We do appreciate the value of stringy techniques in explaining the RHIC results, but ... there will be a better and more quantitative picture. Why $1$ to $3$ GeV (from a proton to a helium3 mass)?

  2. Hi,

    I think that 3 GeV is just the limit to which data are analyzed.

    To me the decay of string like object formed as the hadronic strings at high density created in the collision of high energy nuclei fuse to a long string like object containing quark gluon plasma looks like an elegant explanation for RHIC events. In the recent case the mechanism leading to a long string is different.

    In QCD this kind of long string would not be present since only hadronic strings have QCD justification. In TGD it would correspond to a long and highly (geometrically) entangled color flux tube. For more details see my blog posting.

  3. Somewhere I have read that Monte Carlo simulations are not so exact.

  4. Ulla, the problem is not so much with the Monte Carlo techniques as with the implementation of QCD in the software.

  5. I think that the qualitative aspects of these findings suggesting heavy structures decaying in stringy manner are simply in conflict with the general properties of QCD plasma phase which is expected to be created. Everything should be rather featureless like in black body radiation in the first approximation.

    The assumption that QCD plasma is located at long entangled flux tubes could resolve the problem so that the finding is extremely interesting from TGD point of view. It would also give additional support for the popular idea that the situation is fractally scaled variant of early Big Bang but now in TGD sense. There will be of course many other explanations.

  6. Tommaso today:

    "Indeed, when we compare our experimental results with expectations, the latter are produced with Monte Carlo simulations which, while they contain everything we know about QCD and then some, also require some phenomenological parameters to describe the processes we cannot calculate. Among these parameters are those which model the processes occurring during the fragmentation of quarks and gluons into observable hadronic states.
    Monte Carlo simulations which perform the modeling of non-perturbative regime of QCD require "tuning" to work. This tuning is performed by comparing meaningful observable distributions seen in data with model predictions, then tweaking the phenomenological parameters that enter the modeling to find a better agreement. But once that is done, we only know that the simulation works at the energy regime where we have tuned it.
    I must mention that the feature observed by CMS is interesting in its own right regardless of what simulations predict: that is because the feature is not present in lower-energy interactions, and in lower-particle multiplicities.
    the prediction was based on an extrapolation."

    What really is a gluon? Is it a flux tube between matter and antimatter? A gluon inside the proton = compositeness?

    "Also, deep down in this comments thread, I will venture to speculate that what CMS is seeing is some sort of "string radiation" from the color connections between the quarks in the protons and the partons in the leading jets that."

    WOW, not bad :)

  7. Matti, don't again shake life into the creation of black holes at LHC.

  8. Lol, Ulla, but you can't blame Matti for the inevitable. Most theorists are already thinking of 'black hole physics' here ...

  9. I don't blame him. I only said he should think of the panic it created and avoid talking like he did, so the analogy is fix and ready.

    Guess I did it myself now, sic.

  10. G.A.Miller
    Shapes of the proton.

    Protons are collided, so their shapes are important.
    - the ratio of the proton’s electric and magnetic form factor GE/GM, falls with increasing momentum transfer Q2 for 1< Q2 < 6 GeV2
    - the ratio of Pauli to Dirac form factors, QF2(Q2)/F1(Q2) is a approximately constant, indicates that quarks in the proton carry non-zero orbital angular momentum
    - As a particle of spin 1/2, the proton can have no quadrupole moment, according to the Wigner-Eckhart theorem. Thus any non-spherical manifestation must reside in fluctuating components of the quantum wave function.
    - Another difficulty occurs in using experiments in which momentum is transferred to the proton. The proton’s final state carries different total momentum than that of the initial state (exactly what LHC does)
    - one often thinks of a particle in relativistic motion having a pancake shape because of the effects of Lorentz contraction, caused by external influence
    - Our three-quark wave function is constructed using symmetries; it is asymmetric

    it is worthwhile to briefly explain how the constant nature of the ratio QF2/F1 emerges from the relativistic nature of the calculation. The wave function Eq. (2) is completely anti-symmetric, so we may take J+ to act only on the third quark which absorbs
    the momentum of the virtual photon. The average charge of the third quark in the mixedsymmetric component of Eq. (2) vanishes, so the only component of the wave function that enters in the calculation of electromagnetic form factors is the mixed anti-symmetric component in which the first two quarks have a vanishing total angular momentum. Then the spin of the proton s is governed by the third quark.

    Isn't this exactly what happens?

    I am making too much noise again. I am thou no physicist. I just want to share my findings :)

  11. I have done a little write up on this matter. I use some fairly elementary arguments with the Klein-Gordon equation, dated September 23, and the next day (today) I write further on:

    This really is not about making black holes. It involves a renormalization group (RG) flow between an AdS-brane and a black brane which set the UV and IR limits of the theory. If any of this is correct, which might be suggested due to the large number of degrees of freedom involved with these pp-bar scattering data, it simply means that QCD physics an low energy has a continuous RG flow to high energy stringy physics. The amplitudes for this scale as ~ -g^2log(Q/Λ), and so even at low energy we should get some stringy physics signatures. That is maybe what is going on here. I happen to be working on a related matter and here is a TeX fragment:

    This high energy brane is matched with a low energy IR brane. This brane is one where an observer witnesses clocks slow down as it approaches the boundary. This D-brane is then a black brane, or a black hole. The repelling gravitation of the $AdS$ boundary means this spacetime acts as a bottle that holds the black hole. We consider the $AdS_{m+n}$, for $m~=~2$ or $3$ and $n~=~0$ or $2$. For most of what follows we consider $AdS_{n+3}$ with the two time directions with $R^2~=~-z^+_1z_1^-~+~z^+_2z^-_2$ with hyperbolic definitions
    The resulting metric analogous to the Taub-NUT construction with the harmonic function $\sqrt{H_1H_5}~=~1~-~(r_0/r)^2$ and the $AdS_3$ metric becomes the BTZ black hole metric
    This result similarly extends to $AdS_5$. This is the extreme limit on a wave embedded metric which is periodic along the lightcone direction $y~-~t$. The D1 and D5 brane factors defines these metric elements as $\sqrt{H_1H_5}$. This is extended to the a BPS black hole so that $r^2~-~r_0^2~=$ $(r~-~r_+)(r~-~r_-)$, Here the $r_\pm~=~r_0~\pm~\sqrt{r_0^2~-~Q^2}$ for $Q$ the charge of a gauge theory, such as electromagnetism. This is the BPS black hole, with a metric given by the charge, or BPS charge, $Q$. The extremal limit of the black hole is what we need to consider. The reason is the following. Maldecena demonstrated there exists a correspondence between the isometries on the boundary of the $AdS$ spacetime and the conformal symmetries of a quantum field theory. This is the celebrated $AdS/CFT$ duality theory. The BPS charge of the black hole then share a correspondence with the conformal field theory on the $AdS$ boundary. Further, in the extremal limit the BPS charge has maximal contribution to the spacetime metric, and further the inner and outer horizons of the black hole merge. Then $r_+~=~r_-$ $=~\rho$. The metric assumes the simple form
    ds^2~=~-{{r^2}\over{r^2~-~\rho^2}} (dt^2~-~du^2)~+~{{r~-~\rho)^2}\over{r^2}}
    Then with the substitution $x~=~(r~-~\rho)/\rho$ this reduces to the line element
    ds^2~=~-{{(1~+~x)^2\over{x^2}}(dt^2~-~du^2)~+~{{x^2}\over{(1~+~x^2}}~+~x^2\rho^2 d\Omega^2.
    This reduces the $AdS_5$ spacetime to $AdS_3\times S^2$, or for $u~=~0$ the $AdS_4$ spacetime is reduced to $AdS_2\times S^2$.

  12. To continue, for I think there is a word limit here. This decomposition from AdS_5 to AdS_3 is this peeling business, where conformal sl(2,R)’s are removed. The AdS_5 is the high energy theory, which is a system of isometries dual to the conformal quantum field on S^5. The low energy removal of a conformal group reduces to AdS_3 which is dual to QCD. So at the low energy end of the spectrum, the end of the RG flow the theory appears as QCD. For physics somewhat above the end of RG flow, which is where the standard model symmetry is recovered, Goldstone boson “regenerated” and we should find the 110GeV Higgs, then QCD should I think start to exhibit stringy physics this way.

    Of course there are no black holes generated, only black hole-ish amplitudes in this stringy form. So the whole ridiculous flapdoodle over the LHC making black holes was silly. Besides, cosmic rays at E > 10TeV slam into the atmosphere of Earth, the surface of the moon and everything else all the time, and nothing has been eaten up into black holes.

    Anyway it is my hope that something like this is going on. If we don’t get some Planckian or string physics in the next decade or two then the foundations of physics, whether strings, LQG, or anything else is just math-philosophy. We might as well scrap it all and do something 99% of people really care about, such as brewing beer or growing marijuana.

  13. Ulla, The Miller paper is a reasonable expose on quantum field theory. The shape of the proton is a bit of a conundrum though. It turns out the length contraction is cancelled out by optical effects. In this case we might replace optics by other gauge field interactions other than photons.

  14. Anyway it is my hope that something like this is going on. If we don’t get some Planckian or string physics in the next decade ... we might as well scrap it all.

    Lawrence, for your information, the readers and bloggers at AP have largely scrapped stringy foundations some decades ago. I for one am waiting for the Tevatron to rule out a Higgs boson.

  15. Lawrence,

    You had not even read it (I am angry). There is no optical effects. There is different kinds of shapes, and with the high kinetic energy in the collider the proton is probably very flat. When two flat pieces frontal collide you know what happen? Nobody has talked about photons in the collider? I have asked what the charged particles are? Pions only? Muons? Leptons? I guess that is an important information too? Non-charged particles?

    The creation of gluon plasma is very BigBang-like and black holish. But the energy amount in insufficient to create a black hole? It would have to be doubled. Then the question is automatically arisen, why plasma is created?

  16. Kea,

    String theory is more alive now than it ever has been. As for the Higgs boson, this really is a QFT form of the Landau-Ginsburg potential used in an array of physics, from Curie point of ferromagnetism, to superfluids, superconductivity, Meissner effects and so forth. The Higgsian mechanism is something almost universal in much of the rest of physics. If the Higgs field is absent in particle physics then we should not just scrap it all and start making up perfect single malt scotch, but heavily imbibe in it as well.

  17. On the contrary, Lawrence, category theory and the twistor formalism have demonstrated quite clearly that the standard model (and hence stringy physics) has a non local formulation that is very different from the way you picture things. We have no shortage of ideas to work on. And I am well aware that string theorists think they are doing well and are way ahead of everyone else. We noticed.

  18. Ulla,

    I read the paper rather quickly. No there is no optical effect, which is what I was bringing up as a question. In these presentations on ion collisions one ion is pictured quite often as a pancake shaped object. Yet I have always had my questions about this and whether this taints the physics claimed.


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