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- H J De Vega, A L Larsen, N Sánchez
- 2008

We compute the exact equation of state of circular strings in the (2+1) dimensional de Sitter (dS) and anti de Sitter (AdS) spacetimes, and analyze its properties for the different (oscillating, contracting and expanding) strings. The string equation of state has the perfect fluid form P = (γ − 1)E, with the pressure and energy expressed closely and… (More)

- A L Larsen, N Sánchez
- 1996

We find that the fundamental quadratic form of classical string propagation in 2 + 1 dimensional constant curvature spacetimes solves the Sinh-Gordon equation, the Cosh-Gordon equation or the Liouville equation. We show that in both de Sitter and anti de Sitter spacetimes (as well as in the 2 + 1 black hole anti de Sitter spacetime), all three equations… (More)

- H J De Vega, A L Larsen, N Sánchez
- 1993

The exact general evolution of circular strings in 2 + 1 dimensional de Sitter spacetime is described closely and completely in terms of elliptic functions. The evolution depends on a constant parameter b, related to the string energy, and falls into three classes depending on whether b < 1/4 (oscillatory motion), b = 1/4 (degenerated, hyperbolic motion) or… (More)

- V P Frolov, A L Larsen, M Christensen
- 2008

We study a simple system that comprises all main features of critical gravitational collapse, originally discovered by Choptuik and discussed in many subsequent publications. These features include universality of phenomena, mass-scaling relations, self-similarity, symmetry between super-critical and sub-critical solutions, etc. The system we consider is a… (More)

- A Khan, A L Larsen
- 2008

We point out the existence of some simple string solitons in AdS 5 × S 5 , which at the same time are spinning in AdS 5 and pulsating in S 5 , or vice-versa. This introduces an additional arbitrary constant into the scaling relations between energy and spin or R-charge. The arbitrary constant is not an angular momentum, but can be related to the amplitude… (More)

- A L Larsen, N Sánchez
- 1994

We study the string propagation in the 2+1 black hole anti de Sitter background (2+1 BH-ADS). We find the first and second order fluctuations around the string center of mass and obtain the expression for the string mass. The string motion is stable, all fluctuations oscillate with real frequencies and are bounded, even at r = 0. We compare with the string… (More)

- A Khan, A L Larsen
- 2008

We derive and analyse, analytically and numerically, the equations for perturbations around the pulsating two-spin string soliton in AdS 5 × S 5. We show that the pulsation in S 5 indeed improves the stability properties of the two-spin string soliton in AdS 5 , in the sense that the more pulsation we have, the higher spin we can allow and still have… (More)

- A L Larsen, N Sánchez
- 2008

We perform string quantization in anti de Sitter (AdS) spacetime. The string motion is stable, oscillatory in time with real frequencies ω n = √ n 2 + m 2 α ′2 H 2 and the string size and energy are bounded. The string fluctuations around the center of mass are well behaved. We find the mass formula which is also well behaved in all regimes. There is an… (More)

- A L Larsen, A Khan
- 2008

We find new explicit solutions describing closed strings spinning with equal angular momentum in two independent planes in AdS 5. These are 2N-folded strings in the radial direction and also winding M times around an angular direction. Thus in spacetime they consist of 2N segments. Solutions fulfilling the closed string periodicity conditions exist provided… (More)

- M Christensen, V P Frolov, A L Larsen
- 1998