arXiv subjects

Harsha R. Hampapura

Publications and source records attributed to Harsha R. Hampapura.

6 recordsLinked to original sources

arXiv2020

Target space entanglement in Matrix Models

We study target space entanglement in gauged multi-matrix models as models of entanglement between groups of D-branes separated by a planar entangling surface, paying close attention to the implementation of gauge invariance. We open with a review of target space entanglement between identical particles, which shares some important features (specifically a gauged permutation symmetry) with our main problem. For our matrix models, we implement a gauge fixing well-adapted to the entangling surface. In this gauge, we map the matrix model problem to that of entanglement of a $U(1)$ gauge theory on a complete or all-to-all lattice. Matrix elements corresponding to open strings stretching across the entangling surface in the target space lead to interesting contributions to the entanglement entropy.

hep-th↗

arXiv2019

On phase transitions in the Rényi entropies of 2+1-d large-N interacting vector models

We consider the reduced density matrix for a disc in the ground state of the interacting fixed points of the large-N O(N) vector model in 2+1 dimensions. Using the map to the free energy on $\mathbb{H}_2 \times S^1$, we show that there is an instability in the Rényi entropies at $n = 1$, in the $N \rightarrow \infty$ limit, indicating a phase transition at or near this Rényi parameter. We close with a discussion of the finite-N case.

hep-th↗

arXiv2018

Scrambling in Two-Dimensional Conformal Field Theories with Light and Smeared Operators

We study quantum chaos in two dimensional conformal field theories, building on the work analyzing the out-of-time order thermal correlation functions using large-c Virasoro blocks. Our work investigates the contribution of light intermediate channels and smearing length scales to the four-point function and scrambling. Precise relations for how light intermediate channels increase the scrambling time and how smearing length scales smaller than the thermal length scale decrease the scrambling time are derived.

hep-th↗

arXiv2016

Two-dimensional RCFT's without Kac-Moody symmetry

Using the method of modular-invariant differential equations, we classify a family of Rational Conformal Field Theories with two and three characters having no Kac-Moody algebra. In addition to unitary and non-unitary minimal models, we find "dual" theories whose characters obey bilinear relations with those of the minimal models to give the Moonshine Module. In some ways this relation is analogous to cosets of meromorphic CFT's. The theory dual in this sense to the Ising model has central charge 47/2 and is related to the Baby Monster Module.

hep-th↗

arXiv2016

Cosets of Meromorphic CFTs and Modular Differential Equations

Some relations between families of two-character CFTs are explained using a slightly generalised coset construction, and the underlying theories (whose existence was only conjectured based on the modular differential equation) are constructed. The same method also gives rise to interesting new examples of CFTs with three and four characters.

hep-th↗

arXiv2015

On 2d Conformal Field Theories with Two Characters

Rational CFT's are classified by an integer $\ell$, the number of zeroes of the Wronskian of their characters in moduli space. For $\ell=0$ they satisfy non-singular modular-invariant differential equations, while for $\ell>0$ the corresponding equations have singularities. We survey CFT's with two characters and $\ell=0,2,3,4$ and verify the consistency, at the level of characters, of some candidate theories with $\ell\ne 0$. For $\ell=2$ there are seven consistents sets of characters. We identify specific combinations of level-1 current algebras that are potential symmetries of the corresponding CFT's.

hep-th↗