162 research outputs found
Kaon electromagnetic production: constraints set by new data
The CLAS data on the photo-production of K+ off the proton are utilised to
study reaction mechanism of the process in frame of the isobaric approach. The
missing D13 resonance is shown to be important for successful description of
the data in the whole kinematical region. Constructed models provide
satisfactory predictions for the process.Comment: 4 pages, 4 figures, contribution to the VIII International Conference
on Hypernuclear & Strange Particle Physics, Jefferson Lab, Virginia, U.S.A.,
October 14-18, 200
Strangeness Electromagnetic Production on Nucleons and Nuclei
Isobar models for the electromagnetic production of kaons are discussed with
emphasis on the K^+ photoproduction at very small kaon angles and K^0
photoproduction on deuteron. Distorted-wave impuls approximation calculations
of the cross sections for the electroproduction of hypernuclei are presented on
the case of the ^{12}B_\Lambda production.Comment: 9 pages, 7 figures, talk presented at the 10th Int. Conference on
Hypernuclear and Strange Particle Physics, Tokai, Japan, Sept. 14 - 18, 200
Meson resonances in forward-angle photoproduction
Assuming that the photoproduction at forward angles and high
energies is dominated by one pion exchange we calculate the mass
distributions for low partial waves. Predictions of the model agree well
Assuming that the photoproduction at forward angles and high
energies is dominated by one pion exchange we calculate the mass
distributions for low partial waves. Predictions of the model agree well with
the experimental data which indicate that the , and waves are
dominated by the , and , resonances
respectively.Comment: 6 pages, 7 figure
Polynomial time ultrapowers and the consistency of circuit lower bounds
A polynomial time ultrapower is a structure given by the set of polynomial time computable functions modulo some ultrafilter. They model the universal theory ∀PV of all polynomial time functions. Generalizing a theorem of Hirschfeld (Israel J Math 20(2):111–126, 1975), we show that every countable model of ∀PV is isomorphic to an existentially closed substructure of a polynomial time ultrapower. Moreover, one can take a substructure of a special form, namely a limit polynomial time ultrapower in the classical sense of Keisler (in: Bergelson, V., Blass, A., Di Nasso, M., Jin, R. (eds.) Ultrafilters across mathematics, contemporary mathematics vol 530, pp 163–179. AMS, New York, 1963). Using a polynomial time ultrapower over a nonstandard Herbrand saturated model of ∀PV we show that ∀PV is consistent with a formal statement of a polynomial size circuit lower bound for a polynomial time computable function. This improves upon a recent result of Krajíček and Oliveira (Logical methods in computer science 13 (1:4), 2017).Peer ReviewedPostprint (author's final draft
Effect of the channel and interference phenomena in the two-pion transitions of charmonia and bottomonia
The basic shape of di-pion mass spectra in the two-pion transitions of both
charmonia and bottomonia states is explained by an unified mechanism based on
contributions of the , and coupled channels
including their interference. The role of the individual resonances in
shaping the di-pion mass distributions in the charmonia and bottomonia decays
is considered.Comment: 8 pages, 4 figures, Talk at the XXIII International Baldin Seminar on
High Energy Physics Problems "Relativistic Nuclear Physics \& Quantum
Chromodynamics" (Dubna, Russia, 19--24 September 2016). arXiv admin note:
text overlap with arXiv:1610.0789
Effect of the and channels and interference phenomena in the two-pion and transitions of charmonia and bottomonia
It is shown that the basic shape of dipion and mass spectra
in decays , ,
and in the two-pion transitions of bottomonia states
are explained by an unified mechanism based on the contribution of the
, and coupled channels including their
interference. The role of the individual resonances in making up the
shape of the dipion mass distributions in the charmonia and bottomonia decays
is considered.Comment: 13 pages, 9 figure
Research and Development of Lightweight Repair Mortars with Focus on Their Resistance to High Temperatures
In this article our research focused on study of basic physical and mechanical parameters of polymer-cement repair materials is presented. Namely the influence of applied aggregates in combination with active admixture is specially considered. New formulas which were exposed in ambient with temperature even to 1000°C were suggested. Subsequently densities and strength characteristics including their changes were evaluated. Selected samples were analyzed using electron microscope. The positive influence of porous aggregates based on sintered ash was definitely demonstrated. Further it was found than in terms of thermal resistance the effective micro silica amount represents 5% to 7.5% of cement weight
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