14,562 research outputs found
Local Operations and Completely Positive Maps in Algebraic Quantum Field Theory
Einstein introduced the locality principle which states that all physical
effect in some finite space-time region does not influence its space-like
separated finite region. Recently, in algebraic quantum field theory, R\'{e}dei
captured the idea of the locality principle by the notion of operational
separability. The operation in operational separability is performed in some
finite space-time region, and leaves unchanged the state in its space-like
separated finite space-time region. This operation is defined with a completely
positive map. In the present paper, we justify using a completely positive map
as a local operation in algebraic quantum field theory, and show that this
local operation can be approximately written with Kraus operators under the
funnel property
The force, power and energy of the 100 meter sprint
At the 2008 Summer Olympics in Beijing, Usain Bolt broke the world record for
the 100 m sprint. Just one year later, at the 2009 World Championships in
Athletics in Berlin he broke it again. A few months after Beijing, Eriksen et
al. studied Bolt's performance and predicted that Bolt could have run about
one-tenth of a second faster, which was confirmed in Berlin. In this paper we
extend the analysis of Eriksen et al. to model Bolt's velocity time-dependence
for the Beijing 2008 and Berlin 2009 records. We deduce the maximum force, the
maximum power, and the total mechanical energy produced by Bolt in both races.
Surprisingly, we conclude that all of these values were smaller in 2009 than in
2008
6D Muon Ionization Cooling with an Inverse Cyclotron
A large admittance sector cyclotron filled with LiH wedges surrounded by
helium or hydrogen gas is explored. Muons are cooled as they spiral
adiabatically into a central swarm. As momentum approaches zero, the momentum
spread also approaches zero. Long bunch trains coalesce. Energy loss is used to
inject the muons into the outer rim of the cyclotron. The density of material
in the cyclotron decreases adiabatically with radius. The sector cyclotron
magnetic fields are transformed into an azimuthally symmetric magnetic bottle
in the center. Helium gas is used to inhibit muonium formation by positive
muons. Deuterium gas is used to allow captured negative muons to escape via the
muon catalyzed fusion process. The presence of ionized gas in the center may
automatically neutralize space charge. When a bunch train has coalesced into a
central swarm, it is ejected axially with an electric kicker pulse.Comment: Five pages. LaTeX, three postscript figure files. To appear in the
AIP Conference Proceedings for COOL05: International Workshop on Beam
Cooling, Galena, IL, 18-23 Sept. 200
Resolution of Nearly Mass Degenerate Higgs Bosons and Production of Black Hole Systems of Known Mass at a Muon Collider
The direct s-channel coupling to Higgs bosons is 40000 times greater for
muons than electrons; the coupling goes as mass squared. High precision
scanning of the lighter and the higher mass and is thus
possible with a muon collider. The and are expected to be nearly
mass degenerate and to be CP even and odd, respectively. A muon collider could
resolve the mass degeneracy and make CP measurements. The origin of CP
violation in the and meson systems might lie in the the
Higgs bosons. If large extra dimensions exist, black holes with
lifetimes of seconds could be created and observed via Hawking
radiation at the LHC. Unlike proton or electron colliders, muon colliders can
produce black hole systems of known mass. This opens the possibilities of
measuring quantum remnants, gravitons as missing energy, and scanning
production turn on. Proton colliders are hampered by parton distributions and
CLIC by beamstrahlung. The ILC lacks the energy reach.Comment: Latex, 5 pages, 2 figures, proceedings to the DPF 2004: Annual
Meeting of the Division of Particles and Fields of APS, 26 August-31 August
2004, Riverside, CA, US
Remarks on Causality in Relativistic Quantum Field Theory
It is shown that the correlations predicted by relativistic quantum field
theory in locally normal states between projections in local von Neumann
algebras \cA(V_1),\cA(V_2) associated with spacelike separated spacetime
regions have a (Reichenbachian) common cause located in the union of
the backward light cones of and . Further comments on causality and
independence in quantum field theory are made.Comment: 10 pages, Latex, Quantum Structures 2002 Conference Proceedings
submission. Minor revision of the order of definitions on p.
Chandra and XMM-Newton Observations of NGC 4214: The Hot Interstellar Medium and the Luminosity Function of Dwarf Starbursts
We present results from Chandra and XMM-Newton X-ray observations of NGC
4214, a nearby dwarf starburst galaxy containing several young regions of very
active star-formation. Starburst regions are known to be associated with
diffuse X-ray emission, and in this case the X-ray emission from the galaxy
shows an interesting morphological structure within the galaxy, clearly
associated with the central regions of active star-formation. Of the two main
regions of star-formation in this galaxy, X-ray emission associated with the
older is identified whereas little is detected from the younger, providing an
insight into the evolutionary process of the formation of superbubbles around
young stellar clusters. The spectra of the diffuse emission from the galaxy can
be fitted with a two temperature component thermal model with kT=0.14keV and
0.52keV, and analysis of this emission suggests that NGC 4214 will suffer a
blow-out in the future.
The point source population of the galaxy has an X-ray luminosity function
with a slope of -0.76. This result, together with those for other dwarf
starburst galaxies (NGC 4449 and NGC 5253), was added to a sample of luminosity
functions for spiral and starburst galaxies. The slope of the luminosity
function of dwarf starbursts is seen to be similar to that of their larger
counterparts and clearly flatter than those seen in spirals. Further
comparisons between the luminosity functions of starbursts and spiral galaxies
are also made.Comment: 16 pages, 12 figures. Accepted for publication in MNRA
Ionization state, excited populations and emission of impurities in dynamic finite density plasmas: I. The generalized collisional-radiative model for light elements
The paper presents an integrated view of the population structure and its role in establishing the ionization state of light elements in dynamic, finite density, laboratory and astrophysical plasmas. There are four main issues, the generalized collisional-radiative picture for metastables in dynamic plasmas with Maxwellian free electrons and its particularizing to light elements, the methods of bundling and projection for manipulating the population equations, the systematic production/use of state selective fundamental collision data in the metastable resolved picture to all levels for collisonal-radiative modelling and the delivery of appropriate derived coefficients for experiment analysis. The ions of carbon, oxygen and neon are used in illustration. The practical implementation of the methods described here is part of the ADAS Project
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