Selected Publications

We construct an efficient Monte Carlo algorithm that overcomes the severe signal-to-noise ratio problems and helps us to accurately compute the conformal dimensions of large-$Q$ fields at the Wilson-Fisher fixed point in the $O(2)$ universality class. Using it we verify a recent proposal that conformal dimensions of strongly coupled conformal field theories with a global $U(1)$ charge can be obtained via a series expansion in the inverse charge $1/Q$. We find that the conformal dimensions of the lowest operator with a fixed charge $Q$ are almost entirely determined by the first few terms in the series.
in PRL, 2017

We study some examples of Yang-Baxter deformations of the $AdS_5 \times S^5$ superstring with non-Abelian classical $r$-matrices which satisfy the homogeneous classical Yang-Baxter equation (CYBE). All of the resulting backgrounds satisfy the generalized type IIB supergravity equations. For some of them, we derive “T-dualized” backgrounds and show that these satisfy the usual type IIB supergravity equations. Remarkably, some of them are locally identical to undeformed $AdS_5 \times S^5$.
Journal of Physics A Highlight, 2016

We calculate the anomalous dimensions of operators with large global charge $J$ in certain strongly coupled conformal field theories in three dimensions, such as the $O(2)$ model and the supersymmetric fixed point with a single chiral superfield and a $W = \Phi^3$ superpotential. Working in a $1/J$ expansion, we find that the large-$J$ sector of both examples is controlled by a conformally invariant effective Lagrangian for a Goldstone boson of the global symmetry. For both these theories, we find that the lowest state with charge $J$ is always a scalar operator whose dimension is $ \Delta(J) = a J^{3 / 2} + b J^{1 / 2} - 0.093$, up to corrections that vanish at large $J$.
In JHEP, 2015

Recent Publications

More Publications

. Conformal dimensions in the large charge sectors at the $O(4)$ Wilson-Fisher fixed point. 2019.


. SUSY and the bi-vector. 2018.


. The large-charge expansion for Schrödinger systems. In JHEP, 2018.


. Killing spinors from classical r-matrices. in J.Phys.A, 2018.


. An AdS/EFT correspondence at large charge. in Nucl.Phys. B, 2018.


. Universal correlation functions in rank 1 SCFTs. 2018.


Selected Talks

We compute conformal dimensions and other physical quantities for strongly coupled conformal field theories in three dimensions with global symmetries. We show how in sectors of large global charge $Q$, the charge acts as a controlling parameter and physical quantities can be explicitly computed in a $1/Q$ perturbative expansion. In the case of the $O(2)$ model we show how the predictions of this approach are in very good agreement with lattice measurements.

We study some (conformal) field theories with global symmetries in the sector where the value of the global charge $ Q $ is large. We find that the low energy excitations of this sector are described by the general form of Goldstone’s theorem in the non-relativistic regime. We also derive the unexpected result that the effective field theory describing such sector of fixed $Q$ contains effective couplings $\lambda_{\rm{eff}}\sim \lambda^b /Q^{a}$, where $ \lambda $ is the original coupling. Hence, largecharge leads to weak coupling.

I discuss a general proof of the following two facts regarding two-dimensional local quantum field theories with non-vanishing gravitational anomaly: 1. these theories do not admit a lattice regularization (this generalizes the renowned Nielsen-Ninomiya theorem); 2. their Hilbert space does not factorize into Hilbert spaces in complementary regions. Fact 2 implies in particular that, in the presence of a non-vanishing gravitational anomaly, the usual definitions of quantum entanglement break down.

Recent & Upcoming Talks

More Talks

Compensating strong coupling with large charge
Thu, 17 Jan, 2019
The unreasonable effectiveness of the largecharge expansion
Tue, 16 Jan, 2018
The unreasonable effectiveness of the large charge expansion
Fri, 5 Jan, 2018
Deformations, defects and a noncommutative spectral curve
Tue, 5 Sep, 2017
The unreasonable effectiveness of effective field theory
Fri, 21 Jul, 2017
Attacking strong coupling with large charge
Thu, 8 Jun, 2017