342 research outputs found
Form factor of the process \gamma^*\gamma^* -->\pi^o for small Virtuality of One of the Photons and QCD Sum Rules
We extend the QCD sum rule analysis of the \gamma^*\gamma^* -->\pi^o form
factor into the region where one of the photons has small virtuality: q^2 <<
Q^2 > 1 GeV^2. In this kinematics, one should perform an additional
factorization of short- and long-distance contributions. The extra
long-distance sensitivity of the three-point amplitude is described by
two-point correlators (bilocals), and the low-momentum dependence of the
correlators involving composite operators of two lowest twists is extracted
from auxiliary QCD sum rules. Our estimates for the form factor at q^2=0, Q^2 >
1 1 GeV^2 are in good agreement with existing experimental data.Comment: 6 pages, uses epsf.sty, 1 eps figur
Quantum feedback control of a solid-state two-level system
We have studied theoretically the basic operation of a quantum feedback loop
designed to maintain the desired phase of quantum coherent oscillations in a
two-level system. Such feedback can suppress the dephasing of oscillations due
to interaction with environment. Prospective experiments can be realized using
metallic single-electron devices or GaAs technology.Comment: 4 pages, 4 figure
Academic Education Chain Operation Model
This paper presents an approach for modelling the educational processes as a value added chain. It is an attempt to use a business approach to interpret and compile existing business and educational processes towards reference models and suggest an Academic Education Chain Operation Model. The model can be used to develop an Academic Chain Operation Reference Model.The work on this publication has been sponsored by the TENCompetence Integrated Project that is funded by the European Commission's 6th Framework Programme, priority IST/Technology Enhanced Learning. Contract 027087 [http://www.tencompetence.org
Grimm in Wonderland: Prompt Engineering with Midjourney to Illustrate Fairytales
The quality of text-to-image generation is continuously improving, yet the
boundaries of its applicability are still unclear. In particular, refinement of
the text input with the objective of achieving better results - commonly called
prompt engineering - so far seems to have not been geared towards work with
pre-existing texts. We investigate whether text-to-image generation and prompt
engineering could be used to generate basic illustrations of popular
fairytales. Using Midjourney v4, we engage in action research with a dual aim:
to attempt to generate 5 believable illustrations for each of 5 popular
fairytales, and to define a prompt engineering process that starts from a
pre-existing text and arrives at an illustration of it. We arrive at a
tentative 4-stage process: i) initial prompt, ii) composition adjustment, iii)
style refinement, and iv) variation selection. We also discuss three reasons
why the generation model struggles with certain illustrations: difficulties
with counts, bias from stereotypical configurations and inability to depict
overly fantastic situations. Our findings are not limited to the specific
generation model and are intended to be generalisable to future ones.Comment: 19th Conference on Information and Research science Connecting to
Digital and Library Science, February 23-24, 2023, Bari, Ital
Quantum Nondemolition Squeezing of a Nanomechanical Resonator
We show that the nanoresonator position can be squeezed significantly below
the ground state level by measuring the nanoresonator with a quantum point
contact or a single-electron transistor and applying a periodic voltage across
the detector. The mechanism of squeezing is basically a generalization of
quantum nondemolition measurement of an oscillator to the case of continuous
measurement by a weakly coupled detector. The quantum feedback is necessary to
prevent the ``heating'' due to measurement back-action. We also discuss a
procedure of experimental verification of the squeezed state.Comment: 9 pages, 3 figure
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