Tuesday, September 21, 2010

Quark gluon plasma which does not behave as it should

The first interesting findings from LHC have been reported. The full article is here. In some proton-proton collisions more than hundred particles are produced suggesting a single object from which they are produced. Since the density of matter approaches to that observed in heavy ion collisions for five years ago at RHIC, a formation of quark gluon plasma and its subsequent decay is what one would expect. The observations are not however quite what QCD plasma picture would allow to expect. What is so striking is the evolution of long range correlations between particles in events containing more than 90 particles as the transverse momentum of the particles increases in the range 1-3 GeV (see the excellent description of the correlations by Lubos).

One studies correlation function for two particles as a function of two variables. The first variable is the difference Δ φ for the emission angles and second is essentially the difference for the velocities described relativistically by the difference Δ η for hyperbolic angles. As the transverse momentum pT increases the correlation function develops structure. Around origin of Δ η axis a widening plateau develops near Δ Φ=0. Also a wide ridge with almost constant value as function of Δ η develops near Δ φ=π. What this means that particles tend to move collinearly and or in opposite directions. In the latter case their velocity differences are large since they move in opposite directions so that a long ridge develops in Δ η direction.

Ideal QCD plasma would predict no correlations between particles and therefore no structures like this. The radiation of particles would be like blackbody radiation with no correlations between photons. The description in terms of string like object proposed also by Lubos on basis of analysis of the graph showing the distributions as an explanation of correlations looks attractive. The decay of a string like structure producing particles at its both ends moving nearly parallel to the string to opposite directions could be in question.

Since the densities of particles approach those at RHIC, I would bet that the explanation (whatever it is!) of the hydrodynamical behavior observed at RHIC for some years ago should apply also now. When RHIC was in blogs, I constructed a primitive poor man's model for RHIC events and found that I had mentioned stringy structures - among many other things that I would not perhaps mention anymore;-). The introduction of string like objects was natural since in TGD framework even ordinary nuclei are string like objects with nucleons connected by color flux tubes (see this): this predicts a lot of new nuclear physics for which there is some evidence. The basic idea was that in the high density hadronic color flux tubes associated with the colliding nucleon connect to form long highly entangled hadronic strings containing quark gluon plasma. The decay of these structure would explain the strange correlations.

Note: TGD is not string theory although I talk a lot about strings like objects: these objects are three-dimensional and they are an essential element of almost all physics predicted by TGD. Even elementary particles should look string like objects in electro-weak length scales (Kähler magnetic flux tubes with magnetic charges at their ends).

Let us list the main assumptions of the model for the RHIC events and those observed now. Consider first the "macroscopic description".

  1. A critical system associated with confinement-deconfinement transition of the quark-gluon plasma formed in the collision and inhibiting long range correlations would be in question.

  2. The proposed hydrodynamic space-time description was in terms of a scaled variant of what I call critical cosmology defining a universal space-time correlate for criticality: the specific property of this cosmology is that the mass contained by comoving volume approaches to zero at the the initial moment so that Big Bang begins as a silent whisper and is not so scaring;-). Criticality means flat 3-space instead of Lobatchevski space and means breaking of Lorentz invariance to SO(4). Breaking of Lorentz invariance was indeed observed for particle distributions but now I am not so sure whether it has much to do with this.

The microscopic level the description would be like follows.
  1. A highly entangled long hadronic string like object (color-magnetic flux tube) would be formed at high density of nucleons via the fusion of ordinary hadronic color-magnetic flux tubes to much longer one and containing quark gluon plasma. In QCD world plasma would not be at flux tube.

  2. This entangled string like object would straighten and split to hadrons in the subsequent "cosmological evolution" and yield large numbers of almost collinear particles. The initial situation should be apart from scaling similar as in cosmology where a highly entangled soup of cosmic strings (magnetic flux tubes) precedes the space-time as we understand it. Maybe ordinary cosmology could provide analogy as galaxies arranged to form linear structures?

  3. This structure would have also black hole like aspects but in totally different sense as the 10-D hadronic black-hole proposed by Nastase to describe the findings. Note that M-theorists identify black holes as highly entangled strings: in TGD 1-D strings are replaced by 3-D string like objects.


Ulla said...

When you have so tiny, small structures, are there enough of degrees of freedom to achieve coherence, or is the coherence coming from the environment?

Ulla said...

In quantum mechanics, each Pauli matrix represents an observable describing the spin of a spin ½ particle in the three spatial directions. Also, as an immediate consequence of the Cartan decomposition mentioned above, iσj are the generators of rotation acting on non-relativistic particles with spin ½. The state of the particles are represented as two-component spinors. An interesting property of spin ½ particles is that they must be rotated by an angle of 4π in order to return to their original configuration. This is due to the two-to-one correspondence between SU(2) and SO(3) mentioned above, and the fact that, although one visualizes spin up/down as the north/south pole on the 2-sphere S2, they are actually represented by orthogonal vectors in the two dimensional complex Hilbert space.


Matti Pitkänen said...

There is a lot of energy. For instance, center of mass energy of TeV for the colliding protons means the mass of thousand protons and 2 million electrons and milion million visible photons! Huge number of particles is created in the process. Therefore the comparison with Big Bang is rather good.

Quarks and gluons could form quantum coherent phase in the phase transition to hadronic phase via a formation of long string like objects containing the quark gluon plasma which then splits to ordinary hadronic strings. I have proposed that also a phase transition increasing the value of Planck constant could occur.

Ulla said...

Well, I thought that a spin 1/2 would mean opposite directions, leading to exactly this figure? But I don't know so much about the procedure. The exclusion also says so. Lubos also talked of magnetic strings.

For you this is fantastic good news :) You must be very happy. Let me summarize:

Tommaso: 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.

Lawrence: Matti might in some sense have the right suggestion. Of course it is hard to know for certain what this implies, but this does look similar to what we might expect of correlations between QCD and AdS or black hole, or BH-like, physics.
Assume a cosmology is in an entanglement with other spacetime cosmologies. I like to keep my sights somewhat elevated. (viXra blog)

Phil: The Regge trajectory, where they first started talking about string tension as the slope of the energy of hadron states with increasing spin, is just one example. Hadron jets are the consequence of what happens when the string breaks.
What we are seeing here might be something more. I don’t mean it has to be a Beyond Standard Model phenomena (which it could be), just that it is something non-perturbative (viXra blog)

This means exactly topology and fractality. It is present already at this stage.

Lubos: The correlation function: the likelihood that charged particles are emitted in angles that differ by "delta phi" and velocities that differ by the hyperbolic Lorentzian angle "delta eta".
(Means that particles are not emitted randomly, but in a directed way.)

there is clearly "something" around 1-10 GeV or higher that wants to decay into many, almost perfectly aligned or anti-aligned charged particles. what is the "something"? Well, it surely looks like an extended object of some kind - I would conservatively choose a dual string - or a flux tube - with quarks at the endpoints. Its length is a few fermi, it wants to be really straight as it is stretched, and when it is forced to break, it creates many smaller charged strings that move in the same or opposite direction. I would offer is that they are seeing some stringy features of ordinary QCD rather than "new particles".

These QCD strings are just fluxtubes of the QCD "electromagnetic" field. Normal electromagnetic fluxtubes spread all over the space - but QCD has a self-interacting gluon field which likes to clump the fluxtubes and they get compressed into pretty thin fluxtubes. (Reference Frame)

Things has changed very much in a few months. Everyone talks TGD now :) What has happened? Are there some hope of a more wise science of tomorrow after all?

Congratulations. It doesn't matter if this is just a hype. It is the open discussion that leads forward. Soon you will be invited to talk :)

Anonymous said...

Yeah, Matti congrat.

What has happened?