An unexpected bump has the particle physics world busy tonight; (we’re too sedate to be “aflame”). The bump was discovered at Fermilab by the CDF collaboration: Study of multi-muon events produced in p-pbar collisions at sqrt(s)=1.96 TeV”, hep-ex/0810.5357. In short, they’ve discovered a particle that seems to produce jets of leptons.
CDF found that they have way too many events where there are a lot of muons going in the same direction. This sort of thing is called a jet. Normally jets are associated with the strong force, and consequently, they include hadrons as well as leptons. Getting jets without hadrons is very unusual behavior. This is quite exciting but some of the terminology may be a bit confusing in the original paper linked above. There are two types of particles, leptons which do not experience the strong force, and hadrons that do. Physics experiments can distinguish them because hadrons crash into matter and decay, while leptons do not. Leptons eventually end up as electrons and muons. Of these, the electrons are sufficiently light that they get stripped off leaving only the muons. Photons also get absorbed. What’s left is muons and these are detected in the outer parts of a detector. So “punch through” means hadrons that managed to survive all the matter in the inner part of the detector and survived to the part of the detector where muons are supposed to predominate.
Cosmic ray data is pretty much ignored by particle theorists. When I go to conferences, I make sure to attend these lectures because cosmic rays have much greater energies than accelerators can produce, and consequently they are more likely to see new physics. Very few other theoreticians show up at these lectures. Partly for this reason, I haven’t stressed the cosmic ray data very much. But now that the same unusual behavior is being observed at an accelerator, it is time to revisit the cosmic ray data.
A similar set of events were discovered years ago in high energy cosmic ray experiments. They are called “anti-Centauros” (the Centauros are showers that have too many hadrons and not enough leptons, anti-centauros reverse the proportions). Typically, these experiments use photographic emulsion (film) to detect cosmic rays. The film is layered in between sheets of lead or air gaps. The lead breaks up the hadrons and the resulting showers are detected in the film. These events were called “Centauros”, see the article which discusses them: Are Centauros exotic signals of the QGP? by Ewa Gladysz-Dziadus (2001). A more recent update is Very High Energy Cosmic Rays and Their Interactions, Ralph Engel (2005).
The study of cosmic rays is largely ignored, other than the GZK measurement, but the emulsion cosmic ray researchers are still chasing after Centauros. CASTOR stands for “Centauro and Strange Object Research” and is the name for a calorimeter (to measure energy in particle tracks) at the Large Hadron Collider (LHC).
Cosmic ray experimentalists don’t get no respect. Consequently these observations are difficult to publish and when they are published, they are pretty much ignored. But unusual observations in cosmic rays have been piling up for years. Kopenkin and Fujimoto supposedly explained Centauros in 2006: Exotic models are no longer required to explain the Centauro events, but this hasn’t stopped the observations from lacking explanations.
Cosmic rays cause showers. To get the best cosmic ray data, you want to look at the particles before they shower. This tells you more about what the incoming particle is like. This means very high mountain studies, or better, balloon experiments. RUNJOB is the Russian-Nippon Joint Balloon experiment. Most of their papers are uninteresting results about the number of protons and helium nuclei at relatively low energies. However, there are some interesting observations still showing up:
On the data of the treatment of RUNJOB` X-ray emulsion chambers exposed since 1995 to 1999 year about 50 % proton tracks were identified. In remained half of the events from proton group the single charged primary tracks were not found in the search area determined with high accuracy by the triangulation method using the several background heavy tracks. Considered methodical reasons in this paper could not explain this experimental result. The one from the probable physical reasons that is the neutrons in cosmic ray flux does not explain it too.
Preons and Centauros
 Lubos Motl kindly linked this post at his blog so I should probably return the favor and note that the preon model described here uses the “tripled Pauli statistics” that Lubos discovered when looking at quasinormal vibration modes of black holes in An Analytic Computation of Asymptotic Schwarzschild Quasinormal Frequencies (2002). The relationship is given in Bit From Trit, and Lubos’ Booboo.[/edit]
I wrote up a description of how the preons I am working on can explain Centauros back in 2005: A Hidden Dimension, Clifford Algebra, and Centauro Events. The paper uses Clifford (“Geometric”) algebra. Since then I’ve gotten away from using Clifford algebra because few people seem to understand it. The paper runs through calculations I’ve recently done in the Pauli algebra (which is the simplest non trivial Clifford algebra). At that time I didn’t know that the quantum information people were using the same mathematics, so now I follow industry practice and call it mutually unbiased bases (MUBs).
According to this theory, what’s causing the lepton showers (anti-Centauro) is the same particle that also causes the hadron showers of the Centauro event. It is a fraction of a fermion, a preon. In the case of the lepton showers, it is 1/3 of a lepton. This is a free colored particle. In colliding with standard matter, it has approximately equal probabilities of converting to normal (color singlet) matter. If it fails to convert, it continues with its unusual behavior.
Particles that undergo the strong force typically have difficulty interacting with leptons. Since this preon is a fraction of a lepton, it can interact with both leptons and hadrons. Both of them will see the preon as a “pre color” force, with a strength larger than the usual color force. This makes it easy to produce lepton showers. There will also be hadron showers, but CDF may not have looked for these.
The showers are not created by a cascade, but instead are produced a single lepton at a time, consecutively. This means that the leptons are emitted along the path of the preon, they do not all come from the same vertex. This behavior was observed at the CDF in that the various leptons do not share the same vertex.
These preons explain the similarity of the Koide mass equations for the leptons with the mass equations for heavy quarkonium and other mesons (and there are many more mass fits waiting to be published). In this model the color force is just the remains of the pre-color force of the preons and acts similarly. This allows leptons to undergo a strong-like force.
In any sort of theory that unifies the quarks and leptons something similar has to happen. A somewhat odd result of this is that I believe that the weak force can change the color of a quark. That is, when an up is converted to a down, the down does not necessarily have to have the same color as the up had. This allows the total color charge to change; instead of obtaining a color neutral universe by initial condition, color neutrality is maintained by energy considerations (color singlet states have lower energies so the exciting things decay to them).
From a calculational point of view, the model amounts to taking the discrete Fourier transform (dFT) over the three generations, or over three meson resonances with the same quantum numbers. And the dFT simplifies the MNS matrix to an amazing degree. As far as the CKM matrix goes, I finally got it into the simple MNS form a few weeks ago. Now Marni Sheppeard and I are working on finding a simplified form for it, and are writing a paper on the new, very elegant and symmetric parameterization for 3×3 unitary matrices.
My most outrageous claim on these particles is that they travel at around , somewhat faster than light. This comes from the requirement that three of them, moving in perpendicular directions, make up a single standard model particle as in the 3+1 dimension Feynman checkerboard model for Dirac particles. This sort of effect is not detectable at CDF, but would cause spurious energy measurements at certain extended air shower (EAS) experiments. This effect is an explanation for the energy anomalies at AGASA and Yakutsk.
In addition, travelling faster than light gives the particles a motion relative to the frame of reference of the earth. This means that the standard model particles that they collide with will not travel parallel with them, but instead will take off at an angle that depends on the relative motion of the reference frame used to measure them. In the case of emulsions, this is the reference frame of the balloon or earth. This results in a series of particles that show up in a line. This anomaly is observed in cosmic rays, but only with very high energy particles. See Alignment in Gamma Hadron Families of Cosmic Rays (1994).
The model suggests that the graviton also travels faster than light. This makes gravity waves more difficult to detect because we cannot know when to look for them; they will arrive at times that are far in advance of when we see the bright flash in the sky. Evidence for gravity waves does not yet exist, but the negative evidence of waves in conjunction with gamma ray bursts is consistent with the idea. See Lack Of Gravitational Wave Prompts Fresh Look At Gamma Ray Burst, Science Daily, (2008).
So the various physics threads that have been thrown on this blog are slowly weaving together. Right now Marni and I are
fighting working on a paper for the MNS and CKM matrices. This is the soft underbelly of physics, the excessive free parameters of the standard model. But eventually the various anomalies will have to be tied up.