BPS Dp-brane Research Articles

Probing tachyon kinks in Newton-Cartan background

In this paper, we perform a systematic analysis of tachyon condensation over string Newton-Cartan (NC) geometry by probing the background with non BPS Dp brane. We construct the finite tachyon effective action for NC geometry and explore the dynamics associated with the tachyon kink on the world-volume of the non BPS Dp brane. We show that under certain specific assumptions, the spatial dependent tachyon condensation leads to an emerging BPS D(p−1) brane dynamics over NC background. We further compute the stress energy tensor and show the equivalence between two different Dp brane configurations in the NC limit.

Decoupling limit and throat geometry of non-susy D3 brane

Recently it has been shown by us that, like BPS Dp branes, bulk gravity gets decoupled from the brane even for the non-susy Dp branes of type II string theories indicating a possible extension of AdS/CFT correspondence for the non-supersymmetric case. In that work, the decoupling of gravity on the non-susy Dp branes has been shown numerically for the general case as well as analytically for some special case. Here we discuss the decoupling limit and the throat geometry of the non-susy D3 brane when the charge associated with the brane is very large. We show that in the decoupling limit the throat geometry of the non-susy D3 brane, under appropriate coordinate change, reduces to the Constable–Myers solution and thus confirming that this solution is indeed the holographic dual of a (non-gravitational) gauge theory discussed there. We also show that when one of the parameters of the solution takes a specific value, it reduces, under another coordinate change, to the five-dimensional solution obtained by Csaki and Reece, again confirming its gauge theory interpretation.

Remarks on the instability of black Dp-branes

We show that for black Dp-branes having charge Q and Hawking temperature T, the product QT7−p is bounded from above for p⩽5 and is unbounded for p=6. While the maximum occurs at some finite value of a parameter for p⩽4, it occurs at infinity of the parameter for p=5. As a consequence, for fixed charge, there are two black Dp-branes (for p⩽4) at any given temperature less than its maximum value, and when the temperature is maximum there is one black Dp-brane. For p=5, there is only one black D5-brane at a given temperature less than its maximum value, whereas, for p=6, since there is no bound for the temperature, there is always a black D6-brane solution at a given temperature. Of the two black Dp-branes (for p⩽4), one is large which is shown to be thermodynamically unstable and the other is small which is stable. But for p=5,6, the black Dp-branes are always thermodynamically unstable. The stable, small black Dp-brane, however, under certain conditions, can become unstable quantum mechanically and decay either to a BPS Dp-brane or to a Kaluza–Klein “bubble of nothing” through closed string tachyon condensation. The small D5, D6 branes, although classically unstable, have the same fate under similar conditions.

Hawking-Page phase transition of black Dp-branes and R-charged black holes with an IR cutoff

We show that the confinement-deconfinement phase transition of supersymmetric Yang-Mills theories with 16 supercharges in various dimensions can be realized through the Hawking-Page phase transition between the near horizon geometries of black Dp-branes and BPS Dp-branes by removing a small radius region in the geometry in order to realize a confinement phase, which generalizes the Herzog's discussion for the holographic hard-wall AdS/QCD model. Removing a small radius region in the gravitational dual corresponds to introducing an IR cutoff in the dual field theory. We also discuss the Hawking-Page phase transition between thermal $AdS_5$, $AdS_4$, $AdS_7$ spaces and R-charged AdS black holes coming from the spherical reduction of the decoupling limit of rotating D3-, M2-, and M5- branes in type IIB supergravity and 11 dimensional supergravity in grand canonical ensembles, where the IR cutoff also plays a crucial role in the existence of the phase transition.

Note About Non-BPS and BPS Dp-branes in Near Horizon Region of N Dk-Branes

In this paper we will consider the dynamics of BPS and non-BPS Dp-branes in the background of N Dk-branes. Our approach is based on an existence of the new symmetry of D-brane effective actions that naturally emerges in the near horizon region of the stack of N Dk-branes. Since generally this scaling symmetry is explicitly broken in the Lagrangian we will find the equation that determines the time evolution of the generator of this transformations. Then we will argue that in case when the tachyon living on the worldvolume of unstable D-brane reaches the stable minimum the time evolution of this generator can be easily determined. With the help of the knowledge of the time dependence of this charge we will determine the trajectory of the non-BPS D-brane in the near horizon region of N Dk-branes. In case of BPS Dp-brane probe we will aruge that such a broken scaling symmetry exists as well and the existence of the explicit time dependence of the generator of this symmetry can be used in the solving the equation of motion of the probe Dp-brane in the near horizon region of N Dk-branes.

A construction of commutative D-branes from Lower dimensional non-BPS D-branes

We construct an exact soliton, which represents a BPS Dp-brane, in a boundary string field theory action of infinitely many non-BPS D(p-1)-branes. Furthermore, we show that this soliton can be regarded as an exact soliton in the full string field theory. The world-volume theory of the BPS Dp-brane constructed in this way becomes usual gauge theory on commutative R^{p+1}, instead of non-commutative plane. We also construct a D$p$-brane from non-BPS D(p-n)-branes by the ABS like configuration. We confirm that the Dp-brane has correct RR charges and the tension.

Chern-Simons terms on noncommutative branes

We write down couplings of the fields on a single BPS Dp-brane with noncommutative world-volume coordinates to the RR-forms in type II theories, in a manifestly background independent way. This generalises the usual Chern-Simons action for a commutative Dp-brane. We show that the noncommutative Chern-Simons terms can be mapped to Myers terms on a collection of infinitely many D-instantons. We also propose Chern-Simons couplings for unstable non-BPS branes, and show that condensation of noncommutative tachyons on these branes leads to the correct Myers terms on the decay products.