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Proposed astrophysical test of Lorentz invariance
O. Bertolami, C. S. Carvalho
Working in the context of a Lorentz-violating extension of the standard model we show that estimates of Lorentz symmetry violation extracted from ultra-high energy cosmic rays beyo…
Nonminimal coupling and quintessence
O. Bertolami, P. J. Martins
Recent studies of Type Ia Supernovae with redshifts up to about $z~\laq~1$ reveal evidence for a cosmic acceleration in the expansion of the Universe. The most straightforward expl…
Compactification, Vacuum Energy and Quintessence
M. C. Bento, O. Bertolami
We study the possibility that the vacuum energy density of scalar and internal-space gauge fields arising from the process of dimensional reduction of higher dimensional gravity th…
Nucleosynthesis Constraints on a Scale-Dependent New Intermediate Range Interaction
O. Bertolami, F. M. Nunes
We derive constraints on the strength of a new intermediate range interaction that couples to baryon number from primordial nucleosynthesis yields. The nucleosysnthesis limits here…
Seed Magnetic Fields from the Breaking of Lorentz Invariance
O. Bertolami, D. F. Mota
Spontaneous breaking of Lorentz invariance may take place in string theories, possibly endowing the photon with a mass. This leads to the breaking of the conformal symmetry of the…
Gamma-ray bursts, axion emission and string theory dilaton
O. Bertolami
The emission of axions from supernovae is an interesting possibility to account for the Gamma-Ray Bursts provided their energy can be effectively converted into electromagnetic ene…