132 research outputs found
Probing confinement by direct photons and dileptons
The intensive synchrotron radiation resulting from quarks interacting with
the collective confining color field in relativistic heavy ion collisions is
discussed. The spectrum of photons with large transverse momentum is calculated
and compared with the experimental data to demonstrate the feasibility of this
type of radiation. A study of the earlier predicted azimuthal anisotropy in the
angular distribution of dileptons with respect to the three-momentum of the
pair is performed as well. This boundary-induced mechanism of lepton pair
production is shown to possess the features that are distinctly different from
the standard mechanisms and can potentially provide an efficient probe of
quark-gluon plasma formation.Comment: 7 pages, 3 figures, Fig., Refs. and explanations added, typos
corrected, text revise
Three-body correlations in direct reactions: Example of Be populated in reaction
The Be continuum states were populated in the charge-exchange reaction
H(Li,Be) collecting very high statistics data ( events) on the three-body ++ correlations. The
Be excitation energy region below MeV is considered, where the
data are dominated by contributions from the and states. It is
demonstrated how the high-statistics few-body correlation data can be used to
extract detailed information on the reaction mechanism. Such a derivation is
based on the fact that highly spin-aligned states are typically populated in
the direct reactions.Comment: submitted to Physical Review
New insight into the low-energy He spectrum
The spectrum of He was studied by means of the He(,)He
reaction at a lab energy of 25 MeV/n and small center of mass (c.m.) angles.
Energy and angular correlations were obtained for the He decay products by
complete kinematical reconstruction. The data do not show narrow states at
1.3 and 2.4 MeV reported before for He. The lowest resonant
state of He is found at about 2 MeV with a width of 2 MeV and is
identified as . The observed angular correlation pattern is uniquely
explained by the interference of the resonance with a virtual state
(limit on the scattering length is obtained as fm), and with
the resonance at energy MeV.Comment: 5 pages, 4 figures, 2 table
10He low-lying states structure uncovered by correlations
The 0+ ground state of the 10He nucleus produced in the 3H(8He,p)10He
reaction was found at about MeV (\Gamma ~ 2 MeV) above the
three-body 8He+n+n breakup threshold. Angular correlations observed for 10He
decay products show prominent interference patterns allowing to draw
conclusions about the structure of low-energy excited states. We interpret the
observed correlations as a coherent superposition of the broad 1- state having
a maximum at energy 4-6 MeV and the 2+ state above 6 MeV, setting both on top
of the 0+ state "tail". This anomalous level ordering indicates that the
breakdown of the N=8 shell known in 12Be thus extends also to the 10He system.Comment: 5 pages, 5 figure
Cannibalism as a life boat mechanism
Under certain conditions a cannibalistic population can survive when food for the adults is too scarce to support a non-cannibalistic population. Cannibalism can have this lifeboat effect if (i) the juveniles feed on a resource inaccessible to the adults; and (ii) the adults are cannibalistic and thus incorporate indirectly the inaccessible resource. Using a simple model we conclude that the mechanism works when, at low population densities, the average yield, in terms of new offspring, due to the energy provided by one cannibalized juvenile is larger than one
de Branges-Rovnyak spaces: basics and theory
For a contractive analytic operator-valued function on the unit disk
, de Branges and Rovnyak associate a Hilbert space of analytic
functions and related extension space
consisting of pairs of analytic functions on the unit disk . This
survey describes three equivalent formulations (the original geometric de
Branges-Rovnyak definition, the Toeplitz operator characterization, and the
characterization as a reproducing kernel Hilbert space) of the de
Branges-Rovnyak space , as well as its role as the underlying
Hilbert space for the modeling of completely non-isometric Hilbert-space
contraction operators. Also examined is the extension of these ideas to handle
the modeling of the more general class of completely nonunitary contraction
operators, where the more general two-component de Branges-Rovnyak model space
and associated overlapping spaces play key roles. Connections
with other function theory problems and applications are also discussed. More
recent applications to a variety of subsequent applications are given in a
companion survey article
Search for 2p Decay of the First Excited State of 17 Ne
Structure of nuclei located near and beyond the drip-lines plays important role in the explosive astrophysical processes. The problem of two-proton decay of the 17Ne first excited state is a good example of such situation. The two-proton radiative capture is a possible bypass of the 15O waiting point in the rp-process. The rate of this process drastically depends on the value of the weak
Влияние фракционного состава эластичного наполнителя, полученного методом ВСИ, на свойства эластомерных материалов
Ecological and economic problems of rubber goods recycling are considered. In this paper we shall present results of research of influence rubber crumbs on technological and physico-mechanical properties of elasromeric materialsВлияние фракционного состава эластичного наполнителя, полученного методом ВСИ, на свойства эластомерных материало
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