SciPost Phys. 12, 191 (2022) ·
published 10 June 2022

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$\mathrm{T}\overline{\mathrm{T}}$ deformation was originally proposed as an
irrelevant solvable deformation for 2d relativistic quantum field theories
(QFTs). The same family of deformations can also be defined for integrable
quantum spin chains which was first studied in the context of integrability in
AdS/CFT. In this paper, we construct such deformations for yet another type of
models, which describe a collection of particles moving in 1d and interacting
in an integrable manner. The prototype of such models is the LiebLiniger
model. This shows that such deformations can be defined for a very wide range
of systems. We study the finite volume spectrum and thermodynamics of the
$\mathrm{T}\overline{\mathrm{T}}$deformed LiebLiniger model. We find that for
one sign of the deformation parameter $(\lambda<0)$, the deformed spectrum
becomes complex when the volume of the system is smaller than certain critical
value, signifying the break down of UV physics. For the other sign
$(\lambda>0)$, there exists an upper bound for the temperature, similar to the
Hagedorn behavior of the $\mathrm{T}\overline{\mathrm{T}}$ deformed QFTs. Both
behaviors can be attributed to the fact that $\mathrm{T}\overline{\mathrm{T}}$
deformation changes the size the particles. We show that for $\lambda>0$, the
deformation increases the spaces between particles which effectively increases
the volume of the system. For $\lambda<0$, $\mathrm{T}\overline{\mathrm{T}}$
deformation fattens point particles to finite size hard rods. This is similar
to the observation that the action of
$\mathrm{T}\overline{\mathrm{T}}$deformed free boson is the NambuGoto action,
which describes bosonic strings  also an extended object with finite size.
SciPost Phys. 12, 055 (2022) ·
published 9 February 2022

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We study correlation functions of Dbranes and a supergravity mode in AdS,
which are dual to structure constants of two subdeterminant operators with
large charge and a BPS singletrace operator. Our approach is inspired by the
large charge expansion of CFT and resolves puzzles and confusions in the
literature on the holographic computation of correlation functions of heavy
operators. In particular, we point out two important effects which are often
missed in the literature; the first one is an average over classical
configurations of the heavy state, which physically amounts to projecting the
state to an eigenstate of quantum numbers. The second one is the contribution
from wave functions of the heavy state. To demonstrate the power of the method,
we first analyze the threepoint functions in $\mathcal{N}=4$ super YangMills
and reproduce the results in field theory from holography, including the cases
for which the previous holographic computation gives incorrect answers. We then
apply it to ABJM theory and make solid predictions at strong coupling. Finally
we comment on possible applications to states dual to black holes and
fuzzballs.