13,072 research outputs found

### Additional Acceleration of Protons and Energetic Neutrino Production in a Filamentary Jet of the Blazar Markarian 501

Blazars have been regarded as one of the most powerful sources of the highest
energy cosmic rays and also their byproducts, neutrinos. Provided that a
magnetized filamentary system is established in a blazar jet as well, we could
apply the mechanism of multi-stage diffusive shock acceleration to a feasible
TeV emitter, Mrk 501 to evaluate the achievable maximum energy of protons.
Taking conceivable energy restriction into account systematically, it seems
adequate to say that EeV-protons are produced at this site by our present
model. We also estimate neutrino fluxes generated by these accelerated protons
and discuss the detectability based on an updated kilometre-scale telescope
such as IceCube.Comment: 17 pages, 3 Postscript figure

### Program logics for homogeneous meta-programming.

A meta-program is a program that generates or manipulates another program; in homogeneous meta-programming, a program may generate new parts of, or manipulate, itself. Meta-programming has been used extensively since macros
were introduced to Lisp, yet we have little idea how formally to reason about metaprograms. This paper provides the first program logics for homogeneous metaprogramming
â using a variant of MiniMLe by Davies and Pfenning as underlying meta-programming language.We show the applicability of our approach by reasoning about example meta-programs from the literature. We also demonstrate that our logics are relatively complete in the sense of Cook, enable the inductive derivation of characteristic formulae, and exactly capture the observational properties induced by the operational semantics

### False Vacuum in the Supersymmetric Mass Varying Neutrinos Model

We present detailed analyses of the vacuum structure of the scalar potential
in a supersymmetric Mass Varying Neutrinos model. The observed dark energy
density is identified with false vacuum energy and the dark energy scale of
order $(10^{-3}eV)^4$ is understood by gravitationally suppressed supersymmetry
breaking scale, $F({TeV})^2/M_{Pl}$, in the model. The vacuum expectation
values of sneutrinos should be tiny in order that the model works. Some decay
processes of superparticles into acceleron and sterile neutrino are also
discussed in the model.Comment: 7 pages, 5 figures, revtex, typos correcte

### Field-induced commensurate long-range order in the Haldane-gap system NDMAZ

High-field neutron diffraction studies of the new quantum-disordered S=1
linear-chain antiferromagnet Ni(C$_5$H$_{14}$N$_2$)$_2$N$_3$(ClO$_4$) (NDMAZ)
are reported. At T=70 mK, at a critical field $H_c=13.4$ T applied along the
(013) direction, a phase transition to a commensurate N\'{e}el-like ordered
state is observed. The results are discussed in the context of existing
theories of quantum phase transitions in Haldane-gap antiferromagnets, and in
comparions with previous studies of the related system
Ni(C$_5$H$_{14}$N$_2$)$_2$N$_3$(PF$_6$)

### Deformation of LeBrun's ALE metrics with negative mass

In this article we investigate deformations of a scalar-flat K\"ahler metric
on the total space of complex line bundles over CP^1 constructed by C. LeBrun.
In particular, we find that the metric is included in a one-dimensional family
of such metrics on the four-manifold, where the complex structure in the
deformation is not the standard one.Comment: 20 pages, no figure. V2: added two references, filled a gap in the
proof of Theorem 1.2. V3: corrected a wrong statement about Kuranishi family
of a Hirzebruch surface stated in the last paragraph in the proof of Theorem
1.2, and fixed a relevant error in the proof. Also added a reference [24]
about Kuranishi family of Hirzebruch surface

### Large-N reduction for N=2 quiver Chern-Simons theories on S^3 and localization in matrix models

We study reduced matrix models obtained by the dimensional reduction of N=2
quiver Chern-Simons theories on S^3 to zero dimension and show that if a
reduced model is expanded around a particular multiple fuzzy sphere background,
it becomes equivalent to the original theory on S^3 in the large-N limit. This
is regarded as a novel large-N reduction on a curved space S^3. We perform the
localization method to the reduced model and compute the free energy and the
vacuum expectation value of a BPS Wilson loop operator. In the large-N limit,
we find an exact agreement between these results and those in the original
theory on S^3.Comment: 46 pages, 11 figures; minor modification

### On Asynchronous Session Semantics

This paper studies a behavioural theory of the Ï-calculus with session types under the fundamental principles of the practice of distributed computing â asynchronous communication which is order-preserving inside each connection (session), augmented with asynchronous inspection of events (message arrivals). A new theory of bisimulations is introduced, distinct from either standard
asynchronous or synchronous bisimilarity, accurately capturing the semantic nature of session-based asynchronously communicating processes augmented with
event primitives. The bisimilarity coincides with the reduction-closed barbed congruence. We examine its properties and compare them with existing semantics.
Using the behavioural theory, we verify that the program transformation of multithreaded into event-driven session based processes, using Lauer-Needham duality,
is type and semantic preserving

### Atmospheric neutrino flux at INO, South Pole and Pyh\"asalmi

We present the calculation of the atmospheric neutrino fluxes for the
neutrino experiments proposed at INO, South Pole and Pyh\"asalmi. Neutrino
fluxes have been obtained using ATMNC, a simulation code for cosmic ray in the
atmosphere. Even using the same primary flux model and the interaction model,
the calculated atmospheric neutrino fluxes are different for the different
sites due to the geomagnetic field. The prediction of these fluxes in the
present paper would be quite useful in the experimental analysis.Comment: 12Pages,9Fig

### Effects of mirror reflection versus diffusion anisotropy on particle acceleration in oblique shocks

Cosmic ray particles are more rapidly accelerated in oblique shocks, with the
magnetic field inclined with respect to the shock normal direction, than in
parallel shocks, as a result of mirror reflection at the shock surface and
slower diffusion in the shock normal direction. We investigate quantitatively
how these effects contribute to reducing the acceleration time over the whole
range of magnetic field inclinations. It is shown that, for quasi-perpendicular
inclination, the mirror effect plays a remarkable role in reducing the
acceleration time; whereas, at relatively small inclination, the anisotropic
diffusion effect is dominant in reducing that time. These results are important
for a detailed understanding of the mechanism of particle acceleration by an
oblique shock in space and heliosphereic plasmas.Comment: 6 pages, 2 figure

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