Universiteit van Amsterdam
String Theory
Group


Recent results 

► arXiv:1205.5023 (Scaling BPS Solutions and pureHiggs States) Depending
on the value of the coupling, BPS states of type II string theory
compactified on a CalabiYau manifold can be described as multicenter
supergravity solutions or as states on the Coulomb or the Higgs branch
of a quiver gauge theory. While the Coulombbranch states can be mapped
onetoone to supergravity states, this is not automatically so for
Higgsbranch states. In this paper we explicitly compute the BPS
spectrum of the Higgs branch of a threecenter quiver with a closed
loop, and identify the subset of states that are in onetoone
correspondence with Coulomb/supergravity multicenter states. We also
show that there exist additional "pureHiggs" states, that exist if and
only if the charges of the centers can form a scaling solution. Using
generating function techniques we compute the large charge degeneracy
of the "pureHiggs" sector and show that it is always exponential. We
also construct the map between Higgs and Coulombbranch states,
discuss its relation to the HiggsCoulomb map of one of the authors and
Verlinde, and argue that the pure Higgs states live in the kernel of
this map. Given that these states have no obvious description on the
Coulomb branch or in supergravity, we discuss whether they can
correspond to a singlecenter black hole or can be related to more
complicated horizonless configurations. 

► arXiv:1203.1036 (A nonrenormalization theorem for chiral primary 3point functions) In
this note we prove a nonrenormalization theorem for the 3point
functions of 1/2 BPS primaries in the fourdimensional N = 4 SYM and
chiral primaries in two dimensional N =(4,4) SCFTs. Our proof is rather
elementary: it is based on Ward identities and the structure of the
short multiplets of the superconformal algebra and it does not rely on
superspace techniques. We also discuss some possible generalizations to
less supersymmetric multiplets. 

► arXiv:1112.6416
(Anomalous Breaking of Anisotropic Scaling Symmetry in the Quantum Lifshitz Model) In
this note we investigate the anomalous breaking of anisotropic scaling
symmetry $(t,x)\rightarrow(\lambda^z\,t,\lambda\,x)$ in a
nonrelativistic field theory with dynamical exponent $z=2$. On general
grounds, one can show that there exist three possible "central charges"
which characterize the breaking of scale invariance. Using heat kernel
methods, we compute these three central charges in the quantum Lifshitz
model, a free field theory which is second order in time and fourth
order in spatial derivatives. We find that two of the three central
charges vanish. Interestingly, this is also true for strongly coupled
nonrelativistic field theories with a geometric dual described by a
metric and a massive vector field. 
















Research
interests: 

● String theory 
● Quantum
Gravity and Black Holes 
● AdS/CFT,
AdS/QCD,..... 
●
HighEnergy Physics 
●
Mathematical Physics 
●
Condensed Matter Physics 
●
Theoretical Physics in General 
