129 research outputs found
String-Dust Distributions with the Kerr-NUT symmetry
We attempt to solve the Einstein equations for string dust and null flowing
radiation for the general axially symmetric metric, which we believe is being
done for the first time. We obtain the string-dust and radiating
generalizations of the Kerr and the NUT solutions. There also occurs an
interesting case of radiating string-dust which arises from string-dust
generalization of Vaidya's solution of a radiating star.Comment: 15 pages, TeX version. tex error correcte
Teleparallel loop quantum cosmology in a system of intersecting branes
Recently, some authors have removed the big bang singularity in teleparallel
Loop Quantum Cosmology (LQC) and have shown that the universe may undergo a
number of oscillations. We investigate the origin of this type of teleparallel
theory in a system of intersecting branes in M-theory in which the angle
between them changes with time. This system is constructed by two intersecting
anti-D8-branes, one compacted D4-brane and the other a D3-brane. These branes
are built by joining M0-branes which develop in decaying fundamental strings.
The compacted D4-brane is located between two intersecting anti-D8 branes and
glues to one of them. Our universe is located on the D3 brane which wraps the
D4 brane from one end and sticks to one of the anti-D8 branes from another one.
In this system, there are three types of fields, corresponding to compacted D4
branes, intersecting branes and D3-branes. These fields interact with each
other and make the angle between branes oscillate. By decreasing this angle and
approaching the intersecting anti-D8 branes towards each other, the D4 brane
rolls, the D3 brane wraps around the D4 brane, and t he universe contracts. By
separating the intersecting branes and increasing the angle, the D4 brane rolls
in the opposite direction, the D3 brane separates from it and the expansion
branch begins. Also, the interaction between branes in this system gives us the
exact form of the relevant Lagrangian for teleparallel LQC.Comment: 11 page
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