Selected Publications

We investigate the properties of near-conformal dynamics in a sector of large charge when approaching the lower boundary of the conformal window from the chirally broken phase. To elucidate our approach we use the time-honored example of the phenomenologically relevant SU(2) color theory featuring $N_f$ Dirac fermions transforming in the fundamental representation of the gauge group. In the chirally broken phase we employ the effective pion Lagrangian featuring also a pseudo-dilaton to capture a possible smooth conformal-to-non-conformal phase transition. We charge the baryon symmetry of the Lagrangian and study its impact on the ground state and spectrum of the theory as well as the would-be conformal dimensions of the lowest large-charge operator. We moreover study the effects of and dependence on the fermion mass term.
2020

We study the $O(4)$ Wilson–Fisher fixed point in $2+1$ dimensions in fixed large-charge sectors identified by products of two spin-$j$ representations $(j_L,j_R)$. Using effective field theory we derive a formula for the conformal dimensions $D(j_L, j_R)$ of the leading operator in terms of two constants, $c_{ 3 / 2}$ and $c_{ 1 / 2}$, when the sum $j_L + j_R$ is much larger than the difference $|j_L-j_R|$. We compute $D(j_L,j_R)$ when $j_L= j_R$ with Monte Carlo calculations in a discrete formulation of the $O(4)$ lattice field theory, and show excellent agreement with the predicted formula and estimate $c_{ 3 / 2}=1.068(4)$ and $c_{ 1 / 2}=0.083(3)$.
in PRL, 2019

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

. Charging the Conformal Window. 2020.

Preprint

. Yang-Baxter deformations and generalized supergravity - A short summary. 2019.

Preprint

. Near-Conformal Dynamics at Large Charge. 2019.

Preprint

. Large charge at large N. in JHEP, 2019.

Preprint

. O(d,d) transformations preserve classical integrability. In Nucl.Phys.B, 2019.

Preprint

. A safe CFT at large charge. in JHEP, 2019.

Preprint

Selected Talks

We apply the large-charge expansion to O(N) vector models starting from first principles. We focus on the Wilson–Fisher point in three dimensions. We compute conformal dimensions and energies on generic Riemann surfaces at zero and finite temperature, at fixed charge Q in the regime 1 ≪ N ≪ Q. Our approach places the earlier effective field theory treatment on firm ground and extends its predictions.

I will discuss some advanced applications of the large charge expansion for systems with special properties. I will show how to prove some of the general conjectures for the vector models in the limit of large N and show how to completely resum the large-charge perturbative expansion for (non-Lagrangian) N=2 supersymmetric theories in four dimensions.

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.

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

Introduction to the large charge expansion
Thu, 19 Mar, 2020
Introduction to the large charge expansion
Tue, 14 Jan, 2020
Tame the beast: physics at strong coupling
Tue, 22 Oct, 2019
A large charge to tame strong coupling
Tue, 8 Oct, 2019
Large charge at large N
Tue, 27 Aug, 2019
Large charge: advanced applications
Tue, 2 Jul, 2019

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