55,208 research outputs found
Breakdown of the classical double copy for the effective action of dilaton-gravity at NNLO
We demonstrate that a recently proposed classical double copy procedure to construct the effective action of two massive particles in dilaton-gravity from the analogous problem of two color charged particles in Yang-Mills gauge theory fails at next-to-next-to-leading orders in the post-Minkowskian (3PM) or post-Newtonian (2PN) expansions
Quantum state transfer via the ferromagnetic chain in a spatially modulated field
We show that a perfect quantum state transmission can be realized through a
spin chain possessing a commensurate structure of energy spectrum, which is
matched with the corresponding parity. As an exposition of the mirror inversion
symmetry discovered by Albanese et. al (quant-ph/0405029), the parity matched
the commensurability of energy spectra help us to present the novel
pre-engineered spin systems for quantum information transmission. Based on the
these theoretical analysis, we propose a protocol of near-perfect quantum state
transfer by using a ferromagnetic Heisenberg chain with uniform coupling
constant, but an external parabolic magnetic field. The numerical results shows
that the initial Gaussian wave packet in this system with optimal field
distribution can be reshaped near-perfectly over a longer distance.Comment: 5 pages, 2 figure
Understanding the internet topology evolution dynamics
The internet structure is extremely complex. The Positive-Feedback Preference
(PFP) model is a recently introduced internet topology generator. The model
uses two generic algorithms to replicate the evolution dynamics observed on the
internet historic data. The phenomenological model was originally designed to
match only two topology properties of the internet, i.e. the rich-club
connectivity and the exact form of degree distribution. Whereas numerical
evaluation has shown that the PFP model accurately reproduces a large set of
other nontrivial characteristics as well. This paper aims to investigate why
and how this generative model captures so many diverse properties of the
internet. Based on comprehensive simulation results, the paper presents a
detailed analysis on the exact origin of each of the topology properties
produced by the model. This work reveals how network evolution mechanisms
control the obtained topology properties and it also provides insights on
correlations between various structural characteristics of complex networks.Comment: 15 figure
The Calculation of Vacuum Properties from the Global Color Symmetry Model
A modified method for calculating the non-perturbative quark vacuum
condensates from the global color symmetry model is derived. Within this
approach it is shown that the vacuum condensates are free of ultraviolet
divergence which is different from previous studies. As a special, the
two-quark condensate and the mixed quark-gluon condensate are calculated. A
comparision with the results of the other nonperturbative QCD approaches is
given.Comment: 17 page
- …