Effects of the higher partial waves and relativistic terms on the accuracy of the calculation of the hypertriton electroproduction

We have investigated the accuracies of calculations made by omitting the higher partial waves of nuclear wave functions and the elementary relativistic terms in the hypertriton electroproduction. We found that an accurate calculation would still be obtained if we used at least three lowest partial waves with isospin T = 0. Furthermore, we found that the omission of the relativistic terms in the elementary process amplitude could lead to a large deviation from the full calculation. We also present the cpu-times required to calculate the cross sections. For future consideration the use of these lowest partial waves is suggested, since the calculated cross section deviates only about 0.17 nb/sr (approximately 4%), at most, from the full calculation, whereas the cpu-time is reduced by a factor of 60. Comparison of our result with the available experimental data supports these findings.Comment: 12 pages, 4 figures, submitted to Nucl. Phys.

Kaon photoproduction and electroproduction near threshold

We analyze the electromagnetic production of K^+Lambda and K^0Lambda near their production thresholds by using isobar models. In the K^+Lambda channel we show that the model can nicely describe the available experimental data. In the K^0Lambda channel we demonstrate that the K^0 charge form factor has sizable effects on the longitudinal cross section. By extending the model up to W = 1730 MeV, we are able to observe the existence of the narrow P_{11} (J^p = 1/2^+) resonance in the kaon photoproduction process. It is found that the most convincing mass (width) of this resonance is 1650 MeV (5 MeV).Comment: 11 pages, 5 figures, Talk given at Baryons'10: International Conference on the Structure of Baryons, December 7-11, 2010, Osaka, Japa

Photoproduction of Pentaquark in Feynman and Regge Theories

Photoproduction of the Theta+ pentaquark on the proton is analyzed by using an isobar and a Regge models. The difference in the calculated total cross section is found to be more than two orders of magnitude for a hadronic form factor cut-off Lambda > 1 GeV. Comparable results would be obtained for 0.6 < Lambda < 0.8 GeV. We also calculate contribution of the Theta+ photoproduction to the GDH integral. By comparing with the current phenomenological calculation, it is found that the GDH sum rule favors the result obtained from Regge approach and isobar model with small Lambda.Comment: 5 pages, 5 figures, submitted to Phys.Rev.C as a Rapid Communicatio

Analysis of a class of distributed queues with application

Recently we have developed a class of media access control algorithms for different types of Local Area Networks. A common feature of these LAN algorithms is that they represent various strategies by which the processors in the LAN can simulate the availability of a centralized packet transport facility, but whose service incorporates a particular type of change over time known as 'moving sever' overhead. First we describe the operation of moving server systems in general, for both First-Come - First-Served and Head-of-the-Line orders of service, together with an approach for their delay analysis in which we transform the moving server queueing system into a conventional queueing system having proportional waiting times. Then we describe how the various LAN algorithms may be obtained from the ideal moving server system, and how a significant component of their performance characteristics is determined by the performance characteristics of that ideal system. Finally, we evaluate the compatibility of such LAN algorithms with separable queueing network models of distributed systems by computing the interdeparture time distribution for M/M/1 in the presence of moving server overhead. Although it is not exponential, except in the limits of low server utilization or low overhead, the interdeparture time distribution is a weighted sum of exponential terms with a coefficient of variation not much smaller than unity. Thus, we conjecture that a service centre with moving server overhead could be used to represent one of these LAN algorithms in a product form queueing network model of a distributed system without introducing significant approximation errors

Estonia's high current account deficit has special reasons

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