262,763 research outputs found
Subsidization Competition: Vitalizing the Neutral Internet
Unlike telephone operators, which pay termination fees to reach the users of
another network, Internet Content Providers (CPs) do not pay the Internet
Service Providers (ISPs) of users they reach. While the consequent cross
subsidization to CPs has nurtured content innovations at the edge of the
Internet, it reduces the investment incentives for the access ISPs to expand
capacity. As potential charges for terminating CPs' traffic are criticized
under the net neutrality debate, we propose to allow CPs to voluntarily
subsidize the usagebased fees induced by their content traffic for end-users.
We model the regulated subsidization competition among CPs under a neutral
network and show how deregulation of subsidization could increase an access
ISP's utilization and revenue, strengthening its investment incentives.
Although the competition might harm certain CPs, we find that the main cause
comes from high access prices rather than the existence of subsidization. Our
results suggest that subsidization competition will increase the
competitiveness and welfare of the Internet content market; however, regulators
might need to regulate access prices if the access ISP market is not
competitive enough. We envision that subsidization competition could become a
viable model for the future Internet
Graded Symmetry Algebras of Time-Dependent Evolution Equations and Application to the Modified KP equations
By starting from known graded Lie algebras, including Virasoro algebras, new
kinds of time-dependent evolution equations are found possessing graded
symmetry algebras. The modified KP equations are taken as an illustrative
example: new modified KP equations with arbitrary time-dependent
coefficients are obtained possessing symmetries involving arbitrary
functions of time. A particular graded symmetry algebra for the modified KP
equations is derived in this connection homomorphic to the Virasoro algebras.Comment: 19 pages, latex, to appear in J. Nonlinear Math. Phy
Simple parametrization of neutrino mixing matrix
We propose simple forms of neutrino mixing matrix in analogy with the
Wolfenstein parametrization of quark mixing matrix, by adopting the smallest
mixing angle as a measure of expansion parameters with the
tribimaximal pattern as the base matrix. The triminimal parametrization
technique is utilized to expand the mixing matrix under two schemes, i.e., the
standard Chau-Keung (CK) scheme and the original Kobayashi-Maskawa (KM) scheme.
The new parametrizations have their corresponding Wolfenstein-like
parametrizations of quark mixing matrix, and therefore they share the same
intriguing features of the Wolfenstein parametrization. The newly introduced
expansion parameters for neutrinos are connected to the Wolfenstein parameters
for quarks via the quark-lepton complementarity.Comment: 5 pages. Version for publication in PR
Weak Ferromagnetic Exchange and Anomalous Specific Heat in ZnCu3(OH)6Cl2
Experimental evidence for a plethora of low energy spin excitations in the
spin-1/2 kagome antiferromagnet ZnCu3(OH)6Cl2 may be understandable in terms of
an extended Fermi surface of spinons coupled to a U(1) gauge field. We carry
out variational calculations to examine the possibility that such a state may
be energetically viable. A Gutzwiller-projected wavefunction reproduces the
dimerization of a kagome strip found previously by DMRG. Application to the
full kagome lattice shows that the inclusion of a small ferromagnetic
next-nearest-neighbor interaction favors a ground state with a spinon Fermi
surface.Comment: 4 pages, 3 figures, some clarifications to the tex
Pion-photon and photon-pion transition form factors in light-cone formalism
We derive the minimal Fock-state expansions of the pion and the photon wave
functions in light-cone formalism, then we calculate the pion-photon and the
photon-pion transition form factors of and
processes by employing these
quark-antiquark wave functions of the pion and the photon. We find that our
calculation for the transition form factor
agrees with the experimental data at low and moderately high energy scale.
Moreover, the physical differences and inherent connections between the
transition form factors of and have been illustrated, which indicate that these
two physical processes are intrinsically related. In addition, we also discuss
the form factor and the decay width at .Comment: 20 pages, 2 figure
X-ray background and its correlation with the 21 cm signal
We use high resolution hydrodynamical simulations to study the contribution
to the X-ray background from high- energetic sources, such as X-ray
binaries, accreting nuclear black holes and shock heated interstellar medium.
Adopting the model discussed in Eide et al. (2018), we find that these X-ray
sources during the Epoch of Reionization (EoR) contribute less than a few
percent of the unresolved X-ray background. The same sources contribute to less
than 2\% of the measured angular power spectrum of the fluctuations of
the X-ray background. The outputs of radiative transfer simulations modeling
the EoR are used to evaluate the cross-correlations of X-ray background with
the 21~cm signal from neutral hydrogen. Such correlation could be used to
confirm the origin of the 21 cm signal, as well as give information on the
properties of the X-ray sources during the EoR. We find that the correlations
are positive during the early stages of reionization when most of the hydrogen
is neutral, while they become negative when the intergalactic medium gets
highly ionized, with the transition from positive to negative depending on both
the X-ray model and the scale under consideration. With {\tt SKA} as the
reference instrument for the 21~cm experiment, the predicted S/N for such
correlations is if the corresponding X-ray survey is only able to resolve
and remove X-ray sources with observed flux , while the cumulative S/N from to at
is if sources with observed flux are detected.Comment: 9 pages, 8 figure
Melosh rotation: source of the proton's missing spin
It is shown that the observed small value of the integrated spin structure
function for protons could be naturally understood within the naive quark model
by considering the effect from Melosh rotation. The key to this problem lies in
the fact that the deep inelastic process probes the light-cone quarks rather
than the instant-form quarks, and that the spin of the proton is the sum of the
Melosh rotated light-cone spin of the individual quarks rather than simply the
sum of the light-cone spin of the quarks directly.Comment: 5 latex page
Axial vector form factor of nucleons in a light-cone diquark model
The nucleon axial vector form factor is investigated in a light-cone quark
spectator diquark model, in which Melosh rotations are applied to both the
quark and vector diquark. It is found that this model gives a very good
description of available experimental data and the results have very little
dependence on the parameters of the model. The relation between the nucleon
axial constant and the anomalous magnetic moment of nucleons is also discussed.Comment: 8 pages, Revtex4, 1 figure, version to be published in Phys. Rev.
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