# HEP/Astro Seminar -- Monday, 27 November 2000

##
Marginal deformation and creation of codimension ≥ 2
solitons on brane-antibrane pair

### Abstract

After the discovery of the mechanism of tachyon condensation by Sen,
Witten showed that the K-theory is the correct mathematical framework
for describing the phenomena of getting all the lower dimensional BPS
and non-BPS D-branes by condensing tachyonic solitons
of various codimensions on a bunch of D9-D9-pairs (in type IIB theory)
or a bunch of non-BPS D9-branes (in type IIA theory). The exact
conformal field theory describing a codimension one tachyonic soliton
was already known. For codimension = *q* > 1 solitons, it was
conjectured that such a soliton on a D*p*-D*p*-brane pair
represents a D(*p*-*q*)-brane. Witten gave an ansatz
for the higher codimension solitions in his K-theory paper.
In the first part of my talk, I shall establish these results explicitly
for codimension two solitons (vortex/antivortex) by first identifying
a series of marginal deformations which create the vortex-antivortex pair
on the brane-antibrane system and then showing that under this series
of marginal deformations the original D-brane-anti-D-brane system becomes
a D-brane-anti-D-brane system with 2 lower dimension.

In the second part of my talk, I shall apply this method
to a particular example. I shall consider a sytem containing a pair
of non-BPS D-strings of type IIA string theory on a Calabi-Yau 3-fold
orbifold with (*h*^{(1,1)},*h*^{(1,2)})
= (11, 11). After finding the region of stability in the moduli space
for this system, I shall show that the system decays to a pair
of non-BPS D3-branes.

### References

"Vortex pair creation on brane-antibrane pair via marginal deformation,"
Jaydeep Majumder and Ashoke Sen (Harish-Chandra Inst, India).
hep-th/0003124

"Non-BPS D-branes on a Calabi-Yau orbifold,"
Jaydeep Majumder and Ashoke Sen (Harish-Chandra Inst, India).
hep-th/0007158

## 12:30pm, Smith Lab 1094

George T. Fleming
(
gfleming@mps.ohio-state.edu
),
last updated 21 November 2000.