The first of these two papers was previous to that by Andrew Cohen and Sheldon Glashow (September 29), and it already raises the question of spontaneous e+ e− pair emission by the superluminal neutrino. The question of the compatibility of the neutrino superluminal speed with a standard critical speed for the emitting pion, and the fact that such a pion decay may turn out to be impossible, were also evoked in our September 28 paper and further considered in that of September 29.
On October 27, my paper WMAP, Planck, cosmic rays and unconventional cosmologies discussed a different, but related, topic : that of new physics possibly manifesting itself through ultra-high energy cosmic rays (UHECR) and/or signatures of pre-Big Bang cosmologies in WMAP and Planck data. This article updates my contribution to the Planck 2011 Conference (Paris, January 2011).
Recently, the Proceedings of the XXIst International Europhysics Conference on High Energy Physics (Grenoble, France, July 2011) have became available at the address :
including my two papers :
Testing fundamental principles with high-energy cosmic rays, PoS(EPS-HEP2011)390
Pre-Big Bang, vacuum and noncyclic cosmologies, PoS(EPS-HEP2011)479
whose abstracts are :
Testing fundamental principles with high-energy cosmic rays
It is not yet clear  whether the observed flux suppression for ultra-high energy cosmic rays (UHECR) at energies above 4.1019 eV is a signature of the Greisen-Zatsepin-Kuzmin (GZK) cutoff or corresponds, for instance, to the maximum energies available at the relevant sources. Both phenomena can be sensitive to violations of standard special relativity modifying cosmic-ray propagation or acceleration at very high energy [2, 3], and would in principle allow to set bounds on Lorentz symmetry violation (LSV) parameters in models incorporating a privileged local reference frame (the "vacuum rest frame", VRF [4, 5]). But the precise phenomenological analysis of the experimental data is far from trivial, and other effects can be present. The effective parameters can be directly linked to Planck-scale physics, or even to physics beyond Planck scale, as well as to the dynamics and effective symmetries relating LSV mechanisms for nucleons, quarks, leptons and the photon [6, 7]. If a VRF exists, LSV can modify the internal structure of particles at very high energy [7, 8]. Conventional symmetries may also cease to be valid at energies close to the Planck scale. Other possible violations of fundamental principles and conventional basic hypotheses (quantum mechanics, quark confinement, energy and momentum conservation, vacuum homogeneity and "static" properties, effective space dimensions...) can also be considered [8, 9] and possibly tested in high-energy cosmic-ray experiments. Even below UHE (ultra-high energy), exotic signatures cannot be excluded [10, 11]. We present an updated discussion of the theoretical and phenomenological situation, including prospects for earth-based and space experiments and a simple potential interpretation of the observed UHECR composition in terms of LSV where the GZK cutoff would be replaced by spontaneous emission of photons or e+ e− pairs. As the OPERA result  on a possible superluminal propagation of the muon neutrino was announced after the conference, we briefly comment on the consistency problems [13, 14] that a 2.5 x 10−5 critical speed anomaly for the muon neutrino can raise taking into account well-established experimental evidence and astrophysical observations.
Pre-Big Bang, vacuum and noncyclic cosmologies
WMAP and Planck open the way to unprecedented Big Bang phenomenology, potentially allowing to test the standard Big Bang model as well as less conventional approaches including pre-Big Bang cosmologies. An illustration is provided by the recent claim (Gurzadyan et al. ) that the cosmological sky would be a weakly random one with mostly regular signal. This work has been followed by an interesting and useful debate. Whatever the conclusion, it appears that a detailed study of WMAP and Planck data can have significant implications for pre-Big Bang theories. Not only for cyclic cosmologies following the analysis recently proposed by Gurzadyan and Penrose , but also for noncyclic approaches incorporating a new fundamental scale beyond the Planck scale and, possibly, new ultimate constituents of matter with unconventional basic properties as compared to standard particles [3, 4]. Alternatives to standard physics can be considered from a cosmological point of view concerning vacuum structure, the nature of space-time, the origin and evolution of our Universe, the validity of quantum field theory and conventional symmetries, solutions to the cosmological constant problem, inflationary scenarios, dark matter and dark energy, the interpretation of string-like theories... Lorentz-like symmetries for the properties of matter (standard or superbradyonic [5, 6]) can then be naturally stable space-time configurations resulting from general cosmological scenarios that incorporate physics beyond the Planck scale and describe the formation and evolution of the present vacuum. But an even more primordial question seems to be that of the origin of half-integer spins, that cannot be generated through orbital angular momentum in the usual real space-time. It turns out that the use of a spinorial space-time [7, 8] with two complex coordinates instead of the conventional four real ones presents several attractive features. Taking the cosmic time to be the modulus of a SU(2) spinor leads by purely geometric means to a naturally expanding universe [8, 9], with a ratio between cosmic relative velocities and distances equal to the inverse of the age of the Universe. No reference to standard matter, hidden fields, gravitation or relativity is required to get such a result that looks quite reasonable from an observational point of view. We discuss basic ideas and phenomenological issues for noncyclic pre-Big Bang cosmologies in the present context.
(end of the abstracts)
The full texts of these articles are included here :
Testing fundamental principles with high-energy cosmic rays
Pre-Big bang, vacuum and non-cyclic cosmologies
(Note about Proceedings of Science where these papers have been published : All contributions are published in PoS under the terms of the Creative Commons Attribution-NonCommercial-ShareAlike Licence. Every author submitting his/her contribution to PoS retains the copyright, and upon submission (s)he applies this license to his/her work.)
There will be more soon. Happy 2012 !
- Relativity, cosmic rays, cosmology and spinorial space-time (II)
- BICEP2, cosmic inflation, pre-Big Bang, SST, galactic effects...
- BICEP2 Data, CMB B-modes, Inflation, Alternative Cosmologies... (I)
- Are There Evidences For Cosmic Inflation? (II)
- A Privileged Space Direction? Spinorial Space-time, WMAP, Planck (II)