Tuesday, December 10, 2013

New results from PHENIX concerning quark gluon plasma

New results have been published on properties of what is conventionally called quark gluon plasma (QGP) . As a matter fact, this phase does not resemble plasma at all. The decay patterns bring in mind decays of string like objects parallel to the collision axes rather than isotropic blackbody radiation. The initial state looks like a perfect fluid rather than plasma and thus more like a particle like object.

The results of QGP - or color glass condensate (CGC) as it is also called - come from three sources and are very similar. The basic characteristic of the collisions is the cm energy s1/2of nucleon pair. The data sources are Au-Au collisions at RHIC, Brookhaven with s1/2=130 GeV, p-p collisions and p-nucleus collisions at LHC with s1/2=200 GeV and d-Au collisions at RHIC with s1/2=200 GeV studied by PHENIX collaboration.

According to the popular article telling about the findings of PHENIX collaboration the collisions are believed to involve a creation of what is called hot spot. In Au-Au collisions this hot spot has size of order Au nucleus. In d-Au collisions it is reported to be much, much smaller. What does this mean? The size of deuteron nucleus or of nucleon? Or something even much smaller? Hardly so if one believes in QCD picture. If this is however the case, the only reasonable candidate for its size would be the longitudinal size scale of colliding nucleon-nucleon system of order L=hbar/s1/2 if an object with this size is created in the collision. I did my best to find some estimate for the very small size of the hot spot from articles some related to the study but failed (see this, this and this): if I were a paranoid I would see this as a conspiracy to keep this as a state secret;-).

How to understand the findings?

I have already earlier considered the basic characteristics of the collisions. What is called QGP does not behave at all like plasma phase for which one would expect particle distributions mimicking blackbody radiation of quarks and gluons. Strong correlations are found between charged particles created in the collision and the best manner to describe them is in terms of a creation of longitudinal string-like objects parallel to the collision axes.

In TGD framework this observation leads to the proposal that the string like objects could be assigned with M89 hadron physics introduced much earlier to explain strange cosmic ray events like Centauro. The p-adic mass scale assignable to M89 hadron physics is obtained from that of electron (given by p-adic thermodynamics in good approximation by m127= me/51/2) as m89= 2(127-89)/2× me/51/2. This gives m89= 111.8 GeV. This is conveniently below the cm mass of nucleon pair in all the experiments.

In standard approach based on QCD the description is completely different. The basic parameters are now thermodynamical. One assumes that thermalized plasma phase is created and is parametrized by the energy density assignable to gluon fields for which QCD gives the estimate ε ≥ 1 GeV/fm3 and by temperature which is about T=170 GeV and more or less corresponds to QCD Λ. One can think of the collision regions as highly flattened pancake (Lorentz contraction) containing very density gluon phase called color glass condensate, which would be something different from QGP and definitely would not conform with the expectations from perturbative QCD since QGP would be precisely a manifestation of perturbative QGP (see this).

Also a proposal has been made that this phase could be described by AdS/CFT correspondence non-perturbatively - again in conflict with the basic idea that perturbative QCD should work. It has however turned out that this approach does not work even qualitatively as Bee ludicly explains this in her blog article Whatever happened to AdS/CFT and the Quark Gluon Plasma?.

Strangely enough, this failure of QGP and AdS/CFT picture has not created any fuss although one might think that the findings challenging the basic pillars of standard model should be seen as sensational and make happy all those who have publicly told that nothing would be more well-come than the failure of standard model. Maybe particle theorists have enough to do with worrying about the failure of standard SUSY and super string inspired particle phenomenology that they do not want to waste their time to the dirty problems of low energy phenomenology.

A further finding mentioned in the popular article is stronger charm-anticharm suppression in head-on collisions than in peripheral collisions (see this). What is clear that if M89 hadrons are created, they consist of lightest quarks present in the lightest hadrons of M89 hadron physics - that is u and d (and possibly also s) of M89 hadrons, which are scaled variants of ordinary u and d quarks and decay to u and d (and possibly s) quarks of M107 hadron physics. If the probability of creating a hot M89 spot is higher in central than peripheral collisions the charm suppression is stronger. Could a hot M89 spot associated with a nucleon-nucleon pair heat some region around it to M89 hadronic phase so that charm suppression would take place inside larger volume than in periphery?

There is also the question whether the underlying mechanism relies on specks of hot QGP or some inherent property of nuclei themselves. At the first sight, the latter option could not be farther from the TGD inspired vision. However, in nuclear string model inspired by TGD nuclei consists of nucleons connected by color bonds having quark and antiquark at their ends. These bonds are characterized by rather large p-adic prime characterizing current quark mass scale of order 5-20 GeV for u and d quarks (the first rough estimate for the p-adic scales involved is p≈ 2^k, k=121 for 5 MeV and k= 119 for 20 MeV). These color bonds Lorentz contract in the longitudinal direction so that nearly longitudinal color bonds would shorten to M89 scale whereas transversal color bonds would get only thinner. Could they be able to transform to color bonds characterized by M89 and in this manner give rise to M89 mesons decaying to ordinary hadrons?

Flowers to the grave of particle phenomenology

The recent situation in theoretical particle physics and science in general does not raise optimism. Super string gurus are receiving gigantic prizes from a theory that was a failure. SUSY has failed in several fronts and cannot be anymore regarded as a manner to stabilize the mass of Higgs. Although the existence of Higgs is established, the status of Higgs mechanism is challenged by its un-naturality: the assumption that massivation is due to some other mechanism and Higgs has gradient coupling provides a natural explanation for Higgs couplings. The high priests are however talking about "challenges" instead of failures. Even evidence for the failure of even basic QCD is accumulating as explained above. Peter Higgs, a Nobel winner of this year, commented the situation ironically by saying that he would have not got a job in the recent day particle physics community since he is too slow.

The situation is not much better in the other fields of science. Randy Scheckman, also this year's Nobel prize winner in physiology and medicine has declared boycott of top science journals Nature, Cell and Science. Schekman said that the pressure to publish in "luxury" journals encourages researchers to cut corners and pursue trendy fields of science instead of doing more important work. The problem is exacerbated, he said, by editors who were not active scientists but professionals who favoured studies that were likely to make a splash.

Theoretical and experimental particle physics is a marvellous creation of humankind. Perhaps we should bring flowers to the grave of the particle physics phenomenology and have a five minutes' respectful silence. It had to leave us far too early.

For background see the chapter "New particle physics predicted by TGD" of "p-Adic Physics".


Anonymous said...

Dear Matti,

Yes, The recent situation is not optimistic. but it needs patiently debates and discussions with those in academics that are more logical:)

Induced spinor connection on space-time sheet that is electroweak potential is the same connection of space-time that tells how transporting vector in parallel along a curve in space time? but this connection relates to gravity.

Matti Pitkanen said...

Dear Hamed,

you are right. It is however extremely difficult to identify this kind of academics. Most of them take the attitude of brahmin to pariah who refuse to even see those who do not participate group thing. Especially so in Finland.

The spinor structure is not equivalent with the ordinary one: spinors are imbedding space spinors making possible electroweak quantum numbers therefore the induced spinor connection is not equivalent to the ordinary gravitational spinor connection of general relativity deducible from ordinary vierbein. Now spinor connection is derivable from imbedding space 8-bein. This also means that spinor connection is always well-defined unlike in general relativity.

Induced spinor connection corresponds to electroweak gauge potentials, not gravity. Gravity corresponds to coupling to induced metric appearing also in the modified Dirac action since index raising is performed by it.

The interesting point is that modified gamma matrices define a kind of effective metric via anticommutators: does this metric have also some physical meaning is an interesting question.

A further interesting point is the fact that induced gamma matrices and modified gamma matrices mix different M^4 chiralities, only imbedding space chirality is respected: a clear signature about massivation.

Anonymous said...

Dear Matti,

The following arguments as a sequence is the result of my thought in today:). Is there anything right?!

1-Particles touch each of MEs and the effects of them are superposed.
2-MEs can be corresponded to Fourier modes.
3-The Fourier modes in second quantization correspond to gamma matrices of WCW.
4-gamma matrices of WCW corresponded to isometries of WCW.

Hence Particles touches isometries of WCW!!!

In a n-dimensional Euclidean space, a vector can be represented by introduce the standard basis vectors. Corresponding to each basis vector, there is a component of the vector.
In a similar way in WCW, there are isometric generators that are symplectic transformation of deltaCD *CP2. The isometric generators are analogous to the standard basis vectors in finite dimensional Euclidean space.
Every spinor field (and also gauge fields like Maxwell field) can be represented by it’s components on the isometric generators. (just like a vector is represented by it’s components in Euclidean space)

Matti Pitkanen said...

Dear Hamed,

thank you for nice questions. I add my answers below the questions.

1- Particles touch each of MEs and the effects of them are superposed.

A: Right but also more general preferred externals than MEs probably exist: I have talked about Hamilton-Jacobi structure as general property of Minkowskian preferred extrremals. Note that MEs can be also such that light-like curves are curvilinear: for two MEs connected by wormhole contacts this is expected to happen as a consequence of interactions. The wormhole contacts with Kahler magnetic charge can form bound states and for instance rotate around each other. Elementary particles would result in this manner.

2- MEs can be corresponded to Fourier modes.

A: One can assign to MEs superposition of Fourier modes with light-like momenta parallel to ME: the propagation is only in *one* direction. There are also transverse momentum involved due to the localisation to finite thickness so that in this sense one would have tachyonic momenta in Fourier expansion. As in the case of hadrons, only longitudinal momenta however matter.

Only this kind of restricted superposition is possible at the level of single space-time surface and in more general case only effects superpose and this corresponds to disjoint unions of space-time sheets.

To be continued...

Matti Pitkanen said...

Dear Hamed,

Continuation to the previous.

3- The Fourier modes in second quantization correspond to gamma matrices of WCW.
4-gamma matrices of WCW corresponded to isometries of WCW. Hence Particles touches isometries of WCW!!!

A: Here I could not follow completely. I did not get the gist of the last statement.

a) The isometry generators (Killing vector fields) of WCW correspond to Hamiltonians in delta M^4_+xCP_2: hence naturally to partial waves of S^2 (constant radius sphere at light-cone boundary) and of CP_2 and therefore have well-defined angular momentum and color quantum numbers.

b) WCW gamma matrices act like creation and annihilation operators and can be regarded as the super counterparts of Killing vector fields obtained by slashing Killing vector contracted with gamma matrices between spinor field and covariantly constant right handed neutrino. These operators carry lepton number.

c) Much more general set of super generators is obtained by replacing right handed neutrino mode with general solution of modified Dirac equation which is restricted to string world sheet and by integrating. Also these are used in state construction and are indeed necessary since otherwise one would not obtain states with quark number at all!

b) At least these fermionic currents create excitations of particles from ground states with quantum numbers given by imbedding space spinor harmonics in centre of mass degrees of freedom. This important point: imbedding space spinor harmonics generate ground states of the super-conformal representations. This of course just standard wisdom generalised from M^4 to M^4xCP_2.

c) TGD Universe is quantum critical and certainly this means additional degeneracy of physical states since at criticality several extrema of potential function (now Kahler action) coincide. Cusp catastrophe is simple basic example: when the Hessian has rank smaller than maximal, one has criticality.

This criticality should very directly relate to the hierarchy of Planck constants whose description introduces a many-sheeted covering of imbedding space to describe criticality. One might perhaps say that different sheets of covering correspond to the degenerate states classically. Take this with a big grain of salt since I have not analysed this idea more precisely,

I have proposed that zero modes of WCW which do not contribute to its metric give rise to super generators which create states associated with this degeneracy. Also these would be involved in state construction and by above argument should relate closely to the hierarchy of Planck constants.

Admittedly this sounds complicated and I wish I could have so good view about it that I could explain everything with few lines. I do not!

Matti Pitkanen said...

Dear Hamed,

answer to your last question.

4- In a n-dimensional Euclidean space, a vector can be represented by introduce the standard basis vectors. Corresponding to each basis vector, there is a component of the vector.

In a similar way in WCW, there are isometric generators that are symplectic transformation of deltaCD *CP2. The isometric generators are analogous to the standard basis vectors in finite dimensional Euclidean space.

Every spinor field (and also gauge fields like Maxwell field) can be represented by it’s components on the isometric generators. (just like a vector is represented by it’s components in Euclidean space)

A: About the first paragraph I agree completely.

But not about second paragraph. Isometry generators and their super counterparts define an algebra analogous to oscillator operator algebra (super Kac-Moody and symplectic algebras). This can be used to generate particle states from ground states represented in terms of imbedding space spinor harmonics.

If you apply your claim in Minkowski space you would conclude that the modes of spinor fields correspond to 4 translations and 6 Lorentz generators. This cannot be the case.

If you replace "spinor fields" with "spinors at given point", and replace isometries with conformal transformations, the outcome begins to make sense.

The Clifford algebra spanned by gamma matrices creating spinor components from a given standard spinor indeed correspond to translation generators; sigma matrices of Lorentz group, gamma_5 assignable to dilation and gamma_kgamma_5 assignable to special conformal transitions (thus whole Grassmaan algebra with 16 generators correspond to conformal algebra acting as symmetries of YM theory crucial in twistorial considerations).

Note that the polarisations of gauge bosons at given point correspond to translation generators orthogonal to massless momentum.

Anonymous said...

Dear Matti,
So thanks, I need to improve my imagination muscles gradually to understand the WCW :)