FIZIKA B 18 (2009) 2, 81-86

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LETTER TO THE EDITOR

LYRA COSMOLOGY IN D=n+4 DIMENSIONS: THE INTERESTING CASES OF n ³ 6 AND n £ 104

RAMI AHMAD EL-NABULSI
Department of Nuclear and Energy Engineering,
Cheju National University, Ara-dong 1, Jeju 690-756, South Korea
E-mail address: nabulsiahmadrami@yahoo.fr

Received 28 March 2007;   Revised manuscript received 25 February 2009
Accepted 17 June 2009   Online 13 July 2009

Exact solutions of the Einstein's field equations in Lyra geometry in D=4+n dimensional spacetime with time-increasing G and decaying cosmic fluid and density are obtained and discussed in some details. We suggest the phenomenological dissipative law b2 H/t for the square of the non-zero component of the displacement vector field fA. H is the Hubble parameter in the extra-dimensional spacetime metric. It has been observed that the cases n ³ 6 are within the observational limit, the four-dimensional spacetime is in the stage of accelerated expansion, while the extra-dimensions are contracting in time.

PACS numbers: 04.20.Jb; 98.80.Hw
UDC 52-423, 524.83

Keywords: higher-dimensional cosmology, gravitational constant, Lyra geometry, effective pressure

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