Electrostatic in Reissner-Nordstrom space-time with a conical defect

We calculate the electrostatic potential generated by a point charge in the space-time of Reissner-Nordstrom with a conical defect. An expression for the self-energy is also presented.Comment: 7 pages, LATEX fil

Common Subcontracting and Airline Prices

In the US airline industry, independent regional airlines fly passengers on behalf of several national airlines across different markets, giving rise to $\textit{common subcontracting}$. On the one hand, we find that subcontracting is associated with lower prices, consistent with the notion that regional airlines tend to fly passengers at lower costs than major airlines. On the other hand, we find that $\textit{common}$ subcontracting is associated with higher prices. These two countervailing effects suggest that the growth of regional airlines can have anticompetitive implications for the industry

Eternal inflation and the initial singularity

It is shown that a physically reasonable spacetime that is eternally inflating to the future must possess an initial singularity.Comment: 11 pages, Tufts University cosmology preprin

Stochastic inflation on the brane

Chaotic inflation on the brane is considered in the context of stochastic inflation. It is found that there is a regime in which eternal inflation on the brane takes place. The corresponding probability distributions are found in certain cases. The stationary probability distribution over a comoving volume and the creation probability of a de Sitter braneworld yield the same exponential behaviour. Finally, nonperturbative effects are briefly discussed.Comment: 9 page

BPS String Solutions in Non-Abelian Yang-Mills Theories and Confinement

Starting from the bosonic part of N=2 Super QCD with a 'Seiberg-Witten' N=2 breaking mass term, we obtain string BPS conditions for arbitrary semi-simple gauge groups. We show that the vacuum structure is compatible with a symmetry breaking scheme which allows the existence of Z_k-strings and which has Spin(10) -> SU(5) x Z_2 as a particular case. We obtain BPS Z_k-string solutions and show that they satisfy the same first order differential equations as the BPS string for the U(1) case. We also show that the string tension is constant, which may cause a confining potential between monopoles increasing linearly with their distance.Comment: 11 pages, Latex. Minor changes to the text. Final version to appear in Phys. Rev.

Astrophysical Bounds on Global Strings

Global topological defects produce nonzero stress-energy throughout spacetime, and as a result can have observable gravitational influence on surrounding matter. Gravitational effects of global strings are used to place bounds on their cosmic abundance. The minimum separation between global strings is estimated by considering the defects' contribution to the cosmological energy density. More rigorous constraints on the abundance of global strings are constructed by examining the tidal forces such defects will have on observable astrophysical systems. The small number of observed tidally disrupted systems indicates there can be very few of these objects in the observable universe.Comment: 14 pages, REVTe