357 research outputs found
Modular Hamiltonians of excited states, OPE blocks and emergent bulk fields
We study the entanglement entropy and the modular Hamiltonian of slightly
excited states reduced to a ball shaped region in generic conformal field
theories. We set up a formal expansion in the one point functions of the state
in which all orders are explicitly given in terms of integrals of multi-point
functions along the vacuum modular flow, without a need for replica index
analytic continuation. We show that the quadratic order contributions in this
expansion can be calculated in a way expected from holography, namely via the
bulk canonical energy for the entanglement entropy, and its variation for the
modular Hamiltonian. The bulk fields contributing to the canonical energy are
defined via the HKLL procedure. In terms of CFT variables, the contribution of
each such bulk field to the modular Hamiltonian is given by the OPE block
corresponding to the dual operator integrated along the vacuum modular flow.
These results do not rely on assuming large or other special properties of
the CFT and therefore they are purely kinematic.Comment: 40 pages, 2 figures. v3: some typos corrected, references added,
extended discussion on convergence and holographic interpretatio
Warped Weyl fermion partition functions
Warped conformal field theories (WCFTs) are a novel class of non-relativistic
theories. A simple, yet non-trivial, example of such theory is a massive Weyl
fermion in -dimensions, which we study in detail. We derive general
properties of the spectrum and modular properties of partition functions of
WCFTs. The periodic (Ramond) sector of this fermionic system is non-trivial,
and we build two novel partition functions for this sector which have no
counterpart in a CFT. The thermodynamical properties of WCFTs are revisited
in the canonical and micro-canonical ensemble.Comment: 41 page
Echoes of chaos from string theory black holes
The strongly coupled D1-D5 conformal field theory is a microscopic model of
black holes which is expected to have chaotic dynamics. Here, we study the weak
coupling limit of the theory where it is integrable rather than chaotic. In
this limit, the operators creating microstates of the lowest mass black hole
are known exactly. We consider the time-ordered two-point function of light
probes in these microstates, normalized by the same two-point function in
vacuum. These correlators display a universal early-time decay followed by
late-time sporadic behavior. To find a prescription for temporal
coarse-graining of these late fluctuations we appeal to random matrix theory,
where we show that a progressive time-average smooths the spectral form factor
(a proxy for the 2-point function) in a typical draw of a random matrix. This
coarse-grained quantity reproduces the matrix ensemble average to a good
approximation. Employing this coarse-graining in the D1-D5 system, we find that
the early-time decay is followed by a dip, a ramp and a plateau, in remarkable
qualitative agreement with recent studies of the Sachdev-Ye-Kitaev (SYK) model.
We study the timescales involved, comment on similarities and differences
between our integrable model and the chaotic SYK model, and suggest ways to
extend our results away from the integrable limit.Comment: 26 pages, 9 figures, v3: discussion of dip time adde
Films About World War I in Hungary After 1945
https://scholarworks.uno.edu/hlw/1008/thumbnail.jp
Design and implementation of a radio controlled led lighting system
Technological advances allow us to control LED (Light Emitting Diode) lighting at home, in the office it can even allow us to change the intensity of the light and this is just the beginning of what the future holds for us. In this study an LED internal lighting fixture of our own design will be presented focusing on each step in its design. Firstly, the features, types and history of LEDs will be presented, next the products available in market that are required for the completion of the device. Finally, the design and implementation as well as the radio frequency controlled LED indoor lighting fixture will be shown
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