Spacetime noncommutativity and ultrahigh energy cosmic ray experiments

Journal Article · Tue Mar 15 00:00:00 EDT 2011 · Physical Review. D, Particles Fields

DOI:https://doi.org/10.1103/PHYSREVD.83.065013· OSTI ID:21537575

Horvat, Raul; Kekez, Dalibor; Trampetic, Josip ^[1]

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1. Physics Division, Rudjer Boskovic Institute, Zagreb (Croatia)

If new physics were capable of pushing the neutrino-nucleon inelastic cross section 3 orders of magnitude beyond the standard model prediction, then ultrahigh energy (UHE) neutrinos would have already been observed at neutrino observatories. We use such a constraint to reveal information on the scale of noncommutativity (NC) {Lambda}{sub NC} in noncommutative gauge field theories where neutrinos possess a tree-level coupling to photons in a generation-independent manner. In the energy range of interest (10{sup 10} to 10{sup 11} GeV), the {theta} expansion (|{theta}|{approx}1/{Lambda}{sub NC}{sup 2}) and, therefore, the perturbative expansion, in terms of {Lambda}{sub NC}, retains no longer its meaningful character, forcing us to resort to those NC field theoretical frameworks involving the full {theta} resummation. Our numerical analysis of the contribution to the process coming from the photon exchange impeccably pins down a lower bound on {Lambda}{sub NC} to be as high as 900 (450) TeV, depending on the estimates for the cosmogenic neutrino flux. If, on the other hand, one considers a surprising recent result that occurred in Pierre Auger Observatory data, that UHE cosmic rays are mainly composed of highly ionized Fe nuclei, then our bounds get weaker, due to the diminished cosmic neutrino flux. Nevertheless, we show that, even for the very high fraction of heavy nuclei in primary UHE cosmic rays, our method may still yield remarkable bounds on {Lambda}{sub NC}, typically always above 200 TeV. Albeit, in this case, one encounters a maximal value for the Fe fraction, from which any useful information on {Lambda}{sub NC} can be drawn, delimiting thus the applicability of our method.

• OSTI ID: 21537575
• Journal Information: Physical Review. D, Particles Fields, Vol. 83, Issue 6; Other Information: DOI: 10.1103/PhysRevD.83.065013; (c) 2011 American Institute of Physics; ISSN 0556-2821
• Country of Publication: United States
• Language: English

Related Subjects

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS
COMMUTATION RELATIONS
COSMIC NEUTRINOS
COUPLING
CROSS SECTIONS
EEV RANGE
EXPANSION
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GAUGE INVARIANCE
HEAVY NUCLEI
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NUCLEONS
NUMERICAL ANALYSIS
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SPACE-TIME
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IONIZING RADIATIONS
LEPTONS
MASSLESS PARTICLES
MATHEMATICAL MODELS
MATHEMATICS
NEUTRINOS
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RADIATIONS
TEV RANGE
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