808 research outputs found
Cosmological dynamics in tomographic probability representation
The probability representation for quantum states of the universe in which
the states are described by a fair probability distribution instead of wave
function (or density matrix) is developed to consider cosmological dynamics.
The evolution of the universe state is described by standard positive
transition probability (tomographic transition probability) instead of the
complex transition probability amplitude (Feynman path integral) of the
standard approach. The latter one is expressed in terms of the tomographic
transition probability. Examples of minisuperspaces in the framework of the
suggested approach are presented. Possibility of observational applications of
the universe tomographs are discussed.Comment: 16 page
Tomographic entropy and cosmology
The probability representation of quantum mechanics including propagators and
tomograms of quantum states of the universe and its application to quantum
gravity and cosmology are reviewed. The minisuperspaces modeled by oscillator,
free pointlike particle and repulsive oscillator are considered. The notion of
tomographic entropy and its properties are used to find some inequalities for
the tomographic probability determining the quantum state of the universe. The
sense of the inequality as a lower bound for the entropy is clarified.Comment: 19 page
Single neuron transient activity detection by means of tomography
From Twentieth Annual Computational Neuroscience Meeting: CNS*2011
Stockholm, Sweden. 23-28 July 2011(CA) and (ES) are supported by BFU2009-08473. (CA) and (PP) are partially
supported by AYA2009-14212-05.
(PP) is partially supported by TIN2010-21575-C02-01
Tomographic Representation of Minisuperspace Quantum Cosmology and Noether Symmetries
The probability representation, in which cosmological quantum states are
described by a standard positive probability distribution, is constructed for
minisuperspace models selected by Noether symmetries. In such a case, the
tomographic probability distribution provides the classical evolution for the
models and can be considered an approach to select "observable" universes. Some
specific examples, derived from Extended Theories of Gravity, are worked out.
We discuss also how to connect tomograms, symmetries and cosmological
parameters.Comment: 15 page
Identification of baryon resonances in central heavy-ion collisions at energies between 1 and 2 AGeV
The mass distributions of baryon resonances populated in near-central
collisions of Au on Au and Ni on Ni are deduced by defolding the spectra
of charged pions by a method which does not depend on a specific resonance
shape. In addition the mass distributions of resonances are obtained from the
invariant masses of pairs. With both methods the deduced mass
distributions are shifted by an average value of -60 MeV/c relative to the
mass distribution of the free resonance, the distributions
descent almost exponentially towards mass values of 2000 MeV/c^2. The observed
differences between and pairs indicate a contribution
of isospin resonances. The attempt to consistently describe the
deduced mass distributions and the reconstructed kinetic energy spectra of the
resonances leads to new insights about the freeze out conditions, i.e. to
rather low temperatures and large expansion velocities.Comment: 30 pages, 13 figures, Latex using documentstyle[12pt,a4,epsfig], to
appear in Eur. Phys. J.
K^+ production in the reaction at incident energies from 1 to 2 AGeV
Semi-inclusive triple differential multiplicity distributions of positively
charged kaons have been measured over a wide range in rapidity and transverse
mass for central collisions of Ni with Ni nuclei. The transverse
mass () spectra have been studied as a function of rapidity at a beam
energy 1.93 AGeV. The distributions of K^+ mesons are well described by a
single Boltzmann-type function. The spectral slopes are similar to that of the
protons indicating that rescattering plays a significant role in the
propagation of the kaon. Multiplicity densities have been obtained as a
function of rapidity by extrapolating the Boltzmann-type fits to the measured
distributions over the remaining phase space. The total K^+ meson yield has
been determined at beam energies of 1.06, 1.45, and 1.93 AGeV, and is presented
in comparison to existing data. The low total yield indicates that the K^+
meson can not be explained within a hadro-chemical equilibrium scenario,
therefore indicating that the yield does remain sensitive to effects related to
its production processes such as the equation of state of nuclear matter and/or
modifications to the K^+ dispersion relation.Comment: 24 pages Latex (elsart) 7 PS figures to be submitted to Nucl. Phys
Search for DCC in 158A GeV Pb+Pb Collisions
A detailed analysis of the phase space distributions of charged particles and
photons have been carried out using two independent methods. The results
indicate the presence of nonstatistical fluctuations in localized regions of
phase space.Comment: Talk at the PANIC99 Conference, June 9-16, 199
Present Status and Future of DCC Analysis
Disoriented Chiral Condensates (DCC) have been predicted to form in high
energy heavy ion collisions where the approximate chiral symmetry of QCD has
been restored. This leads to large imbalances in the production of charged to
neutral pions. Sophisticated analysis methods are being developed to
disentangle DCC events out of the large background of events with
conventionally produced particles. We present a short review of current
analysis methods and future prospects.Comment: 12 pages, 5 figures. Invited talk presented at the 13th International
Conference on Ultrarelativistic Nucleus-Nucleus Collisions (Quark Matter 97),
Tsukuba, Japan, 1-5 Dec 199
Proximity effect at superconducting Sn-Bi2Se3 interface
We have investigated the conductance spectra of Sn-Bi2Se3 interface junctions
down to 250 mK and in different magnetic fields. A number of conductance
anomalies were observed below the superconducting transition temperature of Sn,
including a small gap different from that of Sn, and a zero-bias conductance
peak growing up at lower temperatures. We discussed the possible origins of the
smaller gap and the zero-bias conductance peak. These phenomena support that a
proximity-effect-induced chiral superconducting phase is formed at the
interface between the superconducting Sn and the strong spin-orbit coupling
material Bi2Se3.Comment: 7 pages, 8 figure
Heavy Quarks and Heavy Quarkonia as Tests of Thermalization
We present here a brief summary of new results on heavy quarks and heavy
quarkonia from the PHENIX experiment as presented at the "Quark Gluon Plasma
Thermalization" Workshop in Vienna, Austria in August 2005, directly following
the International Quark Matter Conference in Hungary.Comment: 8 pages, 5 figures, Quark Gluon Plasma Thermalization Workshop
(Vienna August 2005) Proceeding
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