340,106 research outputs found
The longitudinal fivebrane and tachyon condensation in matrix theory
We study a configuration in matrix theory carying longitudinal fivebrane
charge, i.e. a D0-D4 bound state. We calculate the one-loop effective potential
between a D0-D4 bound state and a D0-anti-D4 bound state and compare our
results to a supergravity calculation. Next, we identify the tachyonic
fluctuations in the D0-D4 and D0-anti-D4 system. We analyse classically the
action for these tachyons and find solutions to the equations of motion
corresponding to tachyon condensation.Comment: 19 page
Holographic phase transition in a non-critical holographic model
We consider a holographic model constructed from the intersecting brane
configuration D4-/D4 in noncritical string theory. We study the
chiral phase diagram of this holographic QCD-like model with a finite baryon
chemical potential through the supergravity dual approximation.Comment: 14 pages, reference adde
Note on a non-critical holographic model with a magnetic field
We consider a noncritical holographic model constructed from an intersecting
brane configuration D4/-D4 with an external magnetic field. We
investigate the influences of this magnetic field on strongly coupled dynamics
by the gauge/gravity correspondence.Comment: 18 pages, references added and typos revise
Intersecting D4-branes Model of Holographic QCD and Tachyon Condensation
We consider the intersecting D4-brane and anti-D4-brane model of holographic
QCD, motivated by the model that has recently been suggested by Van Raamsdonk
and Whyte. We analyze such D4-branes by the use of the action with a
bi-fundamental ``tachyon'' field, so that we find the classical solutions
describing the intersecting D4-branes and the U-shaped D4-branes. We show that
the ``tachyon'' field in the bulk theory provides a current quark mass and a
quark condensate to the dual gauge theory and that the lowest modes of mesons
obtain mass via tachyon condensation. Then evaluating the properties of a pion,
one can reproduce Gell-Mann-Oakes-Renner relation.Comment: 24 pages, 5 figures; v2: refs. added; v3: discussions on Chern-Simons
terms are adde
Quantum Polarization of D4-branes
The low energy effective field theory of type II D4-branes coupled to bulk
supergravity fields is used to investigate {\it quantum} effects for D4-branes
in the D0 supergravity background. Classically, the D4-branes are unaffected by
this background. However, quantum (one-loop) effects are argued to lead to an
induced density of D0-brane charge; e.g., D0-multipole moments on the D4-brane.
The effect is divergent in field theory, but is expected to be cut-off
naturally by stringy corrections.Comment: 15 pages, Some changes in the implications for string theory after
discussions with Friedel Eppl
Multiple D4-D2-D0 on the Conifold and Wall-crossing with the Flop
We study the wall-crossing phenomena of D4-D2-D0 bound states with two units
of D4-brane charge on the resolved conifold. We identify the walls of marginal
stability and evaluate the discrete changes of the BPS indices by using the
Kontsevich-Soibelman wall-crossing formula. In particular, we find that the
field theories on D4-branes in two large radius limits are properly connected
by the wall-crossings involving the flop transition of the conifold. We also
find that in one of the large radius limits there are stable bound states of
two D4-D2-D0 fragments.Comment: 24 pages, 4 figures; v2: typos corrected, minor changes, a reference
adde
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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