37 research outputs found

### Defects in Jackiw-Teitelboim Quantum Gravity

We classify and study defects in 2d Jackiw-Teitelboim gravity. We show these
are holographically described by a deformation of the Schwarzian theory where
the reparametrization mode is integrated over different coadjoint orbits of the
Virasoro group. We show that the quantization of each coadjoint orbit is
connected to 2d Liouville CFT between branes with insertions of Verlinde loop
operators. We also propose an interpretation for the exceptional orbits. We use
this perspective to solve these deformations of the Schwarzian theory,
computing their partition function and correlators. In the process, we define
two geometric observables: the horizon area operator $\Phi_h$ and the geodesic
length operator $L(\gamma)$. We show this procedure is structurally related to
the deformation of the particle-on-a-group quantum mechanics by the addition of
a chemical potential. As an example, we solve the low-energy theory of complex
SYK with a U(1) symmetry and generalize to the non-abelian case.Comment: 66 pages, v4: clarifications added, typos corrected, matches
published versio

### Decoherence and Loss of Entanglement in Acoustic Black Holes

We studied the process of decoherence in acoustic black holes. We focused on
the ion trap model proposed by Horstmann et al. (Phys. Rev. Lett. 104, 250403
(2010)) but the formalism is general to any experimental implementation. For
that particular setup, we computed the decoherence time for the experimental
parameters that they proposed. We found that a quantum to classical transition
occurs during the measurement and we proposed improved parameters to avoid such
a feature. We also studied the entanglement between the Hawking-pair phonons
for an acoustic black hole while in contact with a reservoir, through the
quantum correlations, showing that they remain strongly correlated for small
enough times and temperatures.Comment: 5 pages, 2 figures, accepted in Phys. Rev. Let

### AGT/Z$_2$

We relate Liouville/Toda CFT correlators on Riemann surfaces with boundaries
and cross-cap states to supersymmetric observables in four-dimensional N=2
gauge theories. Our construction naturally involves four-dimensional theories
with fields defined on different Z$_2$ quotients of the sphere (hemisphere and
projective space) but nevertheless interacting with each other. The
six-dimensional origin is a Z$_2$ quotient of the setup giving rise to the
usual AGT correspondence. To test the correspondence, we work out the RP$^4$
partition function of four-dimensional N=2 theories by combining a 3d lens
space and a 4d hemisphere partition functions. The same technique reproduces
known RP$^2$ partition functions in a form that lets us easily check
two-dimensional Seiberg-like dualities on this nonorientable space. As a bonus
we work out boundary and cross-cap wavefunctions in Toda CFT.Comment: 56 pages. v2: Clarify discrete theta angle. v3: Published in JHEP;
extra references. v4: Minor sign fix; extra reference

### New insights on near-extremal black holes

We describe two puzzles that arise from a semiclassical treatment of
near-extremal black hole thermodynamics. Both puzzles are resolved by realizing
that quantum corrections become arbitrarily large at low temperatures, and we
explain how the spectrum and dynamics of near-extremal black holes are
modified. This analysis also implies that without low energy supersymmetry,
such as in the real world, extremal black holes at exactly zero temperature do
not exist since the classical picture breaks down completely. In the context of
supergravity the analysis is modified; supersymmetric extremal black holes do
exist and they are separated from the non-extremal spectrum by a gap power-law
suppressed in the entropy. This justifies black hole microstate counting
performed in the 90's using string theory.Comment: 13 pp; Short article written for the ICTS Newslette

### Bounds on OPE Coefficients from Interference Effects in the Conformal Collider

We apply the average null energy condition to obtain upper bounds on the
three-point function coefficients of stress tensors and a scalar operator,
$\langle TT {\cal O } \rangle,$ in general CFTs. We also constrain the
gravitational anomaly of $U(1)$ currents in four-dimensional CFTs, which are
encoded in three-point functions of the form $\langle TT J \rangle$. In
theories with a large $N$ AdS dual we translate these bounds into constraints
on the coefficient of a higher derivative bulk term of the form $\int
\phi\hspace{.5mm} W^2$. We speculate that these bounds also apply in
de-Sitter. In this case our results constrain inflationary observables, such as
the amplitude for chiral gravity waves that originate from higher derivative
terms in the Lagrangian of the form $\phi \hspace{.5mm}W W^*$.Comment: 46 pages, 3 figure

### Spin-Statistics for Black Hole Microstates

The gravitational path integral can be used to compute the number of black
hole states for a given energy window, or the free energy in a thermal
ensemble. In this article we explain how to use the gravitational path integral
to compute the separate number of bosonic and fermionic black hole microstates.
We do this by comparing the partition function with and without the insertion
of $(-1)^{\sf F}$. In particular we introduce a universal rotating black hole
that contributes to the partition function in the presence of $(-1)^{\sf F}$.
We study this problem for black holes in asymptotically flat space and in AdS,
putting constraints on the high energy spectrum of holographic CFTs (not
necessarily supersymmetric). Finally, we analyze wormhole contributions to
related quantities.Comment: 34 pages; v2: references adde

### 2D dilaton gravity and the Weil-Petersson volumes with conical defects

We derive the Weil-Petersson measure on the moduli space of hyperbolic
surfaces with defects of arbitrary opening angles and use this to compute its
volume. We conjecture a matrix integral computing the corresponding volumes and
confirm agreement in simple cases. We combine this mathematical result with the
equivariant localization approach to Jackiw-Teitelboim gravity to justify a
proposed exact solution of pure 2d dilaton gravity for a large class of dilaton
potentials.Comment: 45p

### Veneziano Amplitude of Vasiliev Theory

We compute the four-point function of scalar operators in CFTs with weakly
broken higher spin symmetry at arbitrary 't Hooft coupling. We use the known
three-point functions in these theories, the Lorentzian OPE inversion formula
and crossing to fix the result up to the addition of three functions of the
cross ratios. These are given by contact Witten diagrams in AdS and manifest
non-analyticity of the OPE data in spin. We use Schwinger-Dyson equations to
show that such terms are absent in the large $N$ Chern-Simons matter theories.
The result is that the OPE data is analytic in spin up to $J=0$.Comment: 30 pages, 6 figures, a missing structure and references adde