# Latest Publications

### Zooming in on AdS$_3$/CFT$_2$ near a BPS Bound

Any $(d+1)$-dimensional CFT with a $U(1)$ flavor symmetry, a BPS bound and an exactly marginal coupling admits a decoupling limit in which one zooms in on the spectrum close to the bound. This limit is an Inönü-Wigner contraction of $so(2,d+1)\oplus u(1)$ that leads to a relativistic algebra with a scaling generator but no conformal generators. In 2D CFTs, Lorentz boosts are abelian and by adding a second $u(1)$ we find a contraction of two copies of $sl(2,\mathbb{R})\oplus u(1)$ to two copies of $P_2^c$, the 2-dimensional centrally extended Poincaré algebra. We show that the bulk is described by a novel non-Lorentzian geometry that we refer to as pseudo-Newton-Cartan geometry. Both the Chern–Simons action on two copies of $sl(2,\mathbb{R})\oplus u(1)$ and the entire phase space of asymptotically AdS$_3$ spacetimes are well-behaved in the corresponding limit if we fix the radial component for the $u(1)$ connections. With this choice, the resulting Newton-Cartan foliation structure is now associated not with time, but with the emerging holographic direction. Since the leaves of this foliation do not mix, the emergence of the holographic direction is much simpler than in AdS$_3$ holography. Furthermore, we show that the asymptotic symmetry algebra of the limit theory consists of a left- and a right-moving warped Virasoro algebra.
preprint, 2017

### Generalized Toda Theory from Six Dimensions and the Conifold

Recently, a physical derivation of the Alday-Gaiotto-Tachikawa correspondence has been put forward. A crucial role is played by the complex Chern-Simons theory arising in the 3d-3d correspondence, whose boundary modes lead to Toda theory on a Riemann surface. We explore several features of this derivation and subsequently argue that it can be extended to a generalization of the AGT correspondence. The latter involves codimension two defects in six dimensions that wrap the Riemann surface. We use a purely geometrical description of these defects and find that the generalized AGT setup can be modeled in a pole region using generalized conifolds. Furthermore, we argue that the ordinary conifold clarifies several features of the derivation of the original AGT correspondence.
JHEP 1712 (2017) 050, 2017

# All Publications

Zooming in on AdS$_3$/CFT$_2$ near a BPS Bound

Linear response of entanglement entropy from holography

# Teaching

During my undergrad, I TA’d for several linear algebra and calculus courses. I also set up a preparatory statistics course for the Amsterdam University College.

After TA-ing statistical physics in the first year of my PhD, I helped set up a master’s course on mathematical methods in theoretical physics. To supplement the course book Topology and Geometry in Physics by Nakahara, Manus Visser and I composed a large number of exercises with typed solutions. The exercises are available upon requests.

# Contact

• g.w.j.oling@uva.nl
• Room C4.261c, University of Amsterdam, Science Park 904, Amsterdam, The Netherlands