30 research outputs found
Dissipation peak as an indicator of sample inhomogeneity in solid He oscillator experiments
A simple phenomenological model is developed for the recent torsional
oscillator experiments on solid He. Within this model, for a homogeneous
sample there is a specific quantitative relation between the change in the
oscillator's frequency and its maximum damping at the apparent supersolid
transition. Much of the published data do not satisfy this relation, indicating
that the dissipation peaks in those samples are strongly inhomogeneously
broadened.Comment: 2 page
Bulk Matter and the Boundary Quantum Null Energy Condition
We investigate the quantum null energy condition (QNEC) in holographic CFTs,
focusing on half-spaces and particular classes of states. We present direct,
and in certain cases nonperturbative, calculations for both the diagonal and
off- diagonal variational derivatives of entanglement entropy. In d > 2, we
find that the QNEC is saturated. We compute relations between the off-diagonal
variation of entanglement, boundary relative entropy, and the bulk stress
tensor. Strong subadditivity then leads to energy conditions in the bulk. In d
= 2, we find that the QNEC is in general not saturated when the Ryu-Takayanagi
surface intersects bulk matter. Moreover, when bulk matter is present the QNEC
can imply new bulk energy conditions. For a simple class of states, we derive
an example that is stronger than the bulk averaged null energy condition and
reduces to it in certain limits.Comment: 22 page
A Conformal Truncation Framework for Infinite-Volume Dynamics
We present a new framework for studying conformal field theories deformed by
one or more relevant operators. The original CFT is described in infinite
volume using a basis of states with definite momentum, , and conformal
Casimir, . The relevant deformation is then considered using
lightcone quantization, with the resulting Hamiltonian expressed in terms of
this CFT basis. Truncating to states with , one can numerically find the resulting spectrum, as well
as other dynamical quantities, such as spectral densities of operators. This
method requires the introduction of an appropriate regulator, which can be
chosen to preserve the conformal structure of the basis. We check this
framework in three dimensions for various perturbative deformations of a free
scalar CFT, and for the case of a free CFT deformed by a mass term and a
non-perturbative quartic interaction at large-. In all cases, the truncation
scheme correctly reproduces known analytic results. We also discuss a general
procedure for generating a basis of Casimir eigenstates for a free CFT in any
number of dimensions.Comment: 48+37 pages, 17 figures; v2: references added, small clarification
Electroweak Corrections from Triplet Scalars
We compute the electroweak S and T parameters induced by SU(2)_L triplet
scalars up to one-loop order. We consider the most general renormalizable
potential for a triplet and the Standard Model Higgs doublet. Our calculation
is performed by integrating out the triplet at the one-loop level and also
includes the one-loop renormalization group running. Effective field theory
framework allows us to work in the phase with unbroken SU(2)_L x U(1)_Y
symmetry. Both S and T parameters exhibit decoupling when all dimensionful
parameters are large while keeping dimensionless ratios fixed. We use bounds on
S and T to constrain the triplet mass and couplings.Comment: 18 page
RG Flow from Theory to the 2D Ising Model
We study 1+1 dimensional theory using the recently proposed method
of conformal truncation. Starting in the UV CFT of free field theory, we
construct a complete basis of states with definite conformal Casimir,
. We use these states to express the Hamiltonian of the full
interacting theory in lightcone quantization. After truncating to states with
, we numerically diagonalize the
Hamiltonian at strong coupling and study the resulting IR dynamics. We compute
non-perturbative spectral densities of several local operators, which are
equivalent to real-time, infinite-volume correlation functions. These spectral
densities, which include the Zamolodchikov -function along the full RG flow,
are calculable at any value of the coupling. Near criticality, our numerical
results reproduce correlation functions in the 2D Ising model.Comment: 31+12 page
N = 1 superconformal blocks for general scalar operators
We use supershadow methods to derive new expressions for superconformal blocks in 4d N = 1 superconformal field theories. We analyze the four-point function ⟨A_1A^†_2B_1B^†_2⟩, where A_i and ℬ_i are scalar superconformal primary operators with arbitrary dimension and R-charge and the exchanged operator is neutral under R-symmetry. Previously studied superconformal blocks for chiral operators and conserved currents are special cases of our general results