3,809 research outputs found
Heavy quark photoproduction at THERA
Measurements of heavy quark production at a possible future facility,
THERA, would provide valuable information on the structure of the photon. QCD
cross-section predictions are made at LO for both charm and beauty production
and their sensitivity to current parametrisations of the photon parton
densities is investigated.Comment: 10 pages, 9 figures. To appear in "The THERA Book",
DESY-LC-REV-2001-062. IFT 2001/
CJK-Improved 5 Flavour LO Parton Distributions in the Real Photon
Radiatively generated, LO quark (u,d,s,c,b) and gluon densities in the real,
unpolarized photon, improved in respect to our previous paper, are presented.
We perform three global fits to the F_2^gamma data, using the LO DGLAP
evolution equation. We improve the treatment of the strong coupling running and
used lower values of Lambda_QCD, as we have found that the too high values
adopted in the previous work caused the high chi^2 of the fits. In addition to
the modified FFNS_CJKL model, referred to as FFNS_CJK 1 we analyse a FFNS_CJK 2
model in which we take into account the resolved-photon heavy-quark
contribution. New CJK model with an improved high-x behavior of the
F_2^gamma(x,Q^2) is proposed. Finally, in the case of the CJK model we abandon
the valence sum rule imposed on the VMD input densities. New fits give chi^2
per degree of freedom about 0.25 better than the old results. All features of
the CJKL model, such as the realistic heavy-quark distributions, good
description of the LEP data on the Q^2 dependence of the F_2^gamma and on
F_2,c^gamma are preserved. Moreover we present results of an analysis of the
uncertainties of the CJK parton distributions due to the experimental errors.
It is based on the Hessian method used for the proton and very recently applied
for the photon by one of us. Parton and structure function parametrizations of
the best fits in both FFNS_CJK and CJK approaches are made accessible. For the
CJK model we provide also sets of test parametrizations which allow for
calculation of uncertainties of any physical value depending on the real photon
parton densities.Comment: 27 pages, 14 figures, FORTRAN programs available at
http://www.fuw.edu.pl/~pjank/param.htm
Heavy Quark Production at the TESLA Collider and its Sensitivity to the Gluon Content in Photon
Heavy quark production is studied at the high energy linear e^+e^- collider
(LC) TESLA both in its nominal and Photon Collider (PC) mode. Leading order
cross-sections are calculated for the production of heavy quarks, e^+e^- ->
e^+e^- Q\bar{Q}X, at high transverse momenta. The sensitivity of this process
to the gluon content in the photon is studied.Comment: 16 pages, Latex, 10 ps figures, uses epsfig.sty. IFT 2001/3
Antenna Design for Semi-Passive UHF RFID Transponder with Energy Harvester
A novel microstrip antenna which is dedicated to UHF semi-passive RFID transponders with an energy harvester is presented in this paper. The antenna structure designed and simulated by using Mentor Graphics HyperLynx 3D EM software is described in details. The modeling and simulation results along with comparison with experimental data are analyzed and concluded. The main goal of the project is the need to eliminate a traditional battery form the transponder structure. The energy harvesting block, which is used instead, converts ambient energy (electromagnetic energy of typical radio communication system) into electrical power for internal circuitry. The additional function (gathering extra energy) of the transponder antenna causes the necessity to create new designs in this scope
An architecture and technology for Ambient Intelligence Node
The era of separate networks is over. The existing technology leaders are preparing a big change in recreation of environment around us. There are several faces for this change. Names like Ambient Intelligence, Ambient Network, IP Multimedia Subsystem and others were created all over the Globe. Regardless of which name is used the new network will combine three main functional principles---it will be: contextual aware, ubiquitous access and intelligent interfaces unified network.
Within this thesis two major aspects are defined. First, the definition of the Ambient Intelligence Environment concept is presented. Secondly the architecture vectors for the technology are named. A short overview of the existing technology is followed by details for the chosen technology---FPGA. The overall specifications are incorporated in the design and demonstration of a basic Ambient Intelligence Node created in the System on the Chip (SoC) FPGA technology
ERS international congress, Madrid, 2019: Highlights from the Epidemiology and Environment Assembly
At the European Respiratory Society's International Congress of 2019, which was held in Madrid, Spain, there were several sessions with exciting poster and oral presentations within the fields of epidemiology and tobacco control. This article is the summary of two of these sessions. One was on the use of Big Data in epidemiology and the other, on the global burden of respiratory disease and tobacco
Shuttle/spacelab MMAP/electromagnetic environment experiment phase B definition study
Progress made during the first five months of the Phase B definition study for the MMAP/Electromagnetic Environment Experiment (EEE) was described. An antenna/receiver assembly has been defined and sized for stowing in a three pallet bay area in the shuttle. Six scanning modes for the assembly are analyzed and footprints for various antenna sizes are plotted. Mission profiles have been outlined for a 400 km height, 57 deg inclination angle, circular orbit. Viewing time over 7 geographical areas are listed. Shuttle interfaces have been studied to determine what configuration the antenna assembly must have to be shared with other experiments of the Microwave Multi-Applications Payload (MMAP) and to be stowed in the shuttle bay. Other results reported include a frequency plan, a proposed antenna subsystem design, a proposed receiver design, preliminary outlines of the experiment controls and an analysis of on-board and ground data processing schemes
Heavy Quark Production at a Linear e^+e^- and Photon Collider and its Sensitivity to the Gluon Content of the Photon
A high energy linear e^+e^- collider (LC) can also be used as a Photon
Collider (PC), using Compton scattering of laser photons on the e^+/e^- beams.
The leading order cross-section for the production of heavy quarks, e^+e^- ->
e^+e^- Q(\bar{Q}) X, at high transverse momenta is calculated for both LC and
PC modes. The sensitivity of this process to the parton distribution
parametrizations of real photons, especially the gluon content, is tested for
both modes.Comment: 8 pages, Latex using epsfig.sty, including 6 postscript figures.
Contribution to Proceedings of the Workshop "Physics Studies for a Future
Linear Collider", Rolf Heuer, Francois Richard and Peter Zerwas Eds., 2000,
DESY 123
Debye mass and heavy quark potential in a PNJL quark plasma
We calculate the Debye mass for the screening of the heavy quark potential in
a plasma of massless quarks coupled to the temporal gluon background governed
by the Polyakov loop potential within the PNJL model in RPA approximation. We
give a physical motivation for a recent phenomenological fit of lattice data by
applying the calculated Debye mass with its suppression in the confined phase
due to the Polyakov-loop to a description of the temperature dependence of the
singlet free energy for QCD with a heavy quark pair at infinite separation. We
compare the result to lattice data.Comment: 6 pages, 1 figure, contribution to Proceedings of the 6th
International Conference on "Critical Point and Onset of Deconfinement", to
appear in Phys. At. Nucl., vol. 7
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