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 photoproduction at THERA

Measurements of heavy quark production at a possible future $ep$ 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/

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

Extracting Personal Behavioral Patterns from Geo-Referenced Tweets

This paper presents an exploratory study of the potential of geo-referenced Twitter data for extracting knowledge about significant personal places, behaviors and potential interests of people. The study was done analysing two months’ worth of tweets from residents of the greater Seattle area

The Russia-Ukraine conflict: lessons for europeans from a polish perspective

O corrente conflito russo-ucraniano alterou novamente o destino da Europa do Leste. No entanto, esta crise deve também ser considerada como um fator perturbador da segurança Europeia. Toda a arquitetura da segurança Europeia foi afetada com a instabilidade do flanco oriental do continente. Se este conflito não servir como um fator unificador da comunidade transatlântica, poderá ser um prenúncio de difíceis tempos vindouros. Acresce, ainda, que este perigo poder-se-á tornar particularmente grave caso se instale a perceção de que a NATO perdeu a sua credibilidade para dissuadir ameaças e a União Europeia a sua capacidade como potência normativa para estimular mudanças no sistema internacional. Inicialmente, este artigo apresenta cinco lições fundamentais que deverão ser retiradas do conflito russo-ucraniano de forma a conter eventuais desafios e ameaças para a Europa. Posteriormente, serão abordadas quatro recomendações que constituem uma base para um plano de ação de políticas securitárias sólidas e de longo prazo como resposta a este conflito.info:eu-repo/semantics/publishedVersio

Towards a holographic realization of the quarkyonic phase

Large-N_c QCD matter at intermediate baryon density and low temperatures has been conjectured to be in the so-called quarkyonic phase, i.e., to have a quark Fermi surface and on top of it a confined spectrum of excitations. It has been suggested that the presence of the quark Fermi surface leads to a homogeneous phase with restored chiral symmetry, which is unstable towards creating condensates breaking both the chiral and translational symmetry. Motivated by these exotic features, we investigate properties of cold baryonic matter in the single flavor Sakai-Sugimoto model searching for a holographic realization of the quarkyonic phase. We use a simplified mean-field description and focus on the regime of parametrically large baryon densities, of the order of the square of the 't Hooft coupling, as they turn out to lead to new physical effects similar to the ones occurring in the quarkyonic phase. One effect, the appearance of a particular marginally stable mode breaking translational invariance and linked with the presence of the Chern-Simons term in the flavor brane Lagrangian, is known to occur in the deconfined phase of the Sakai-Sugimoto model, but turns out to be absent here. The other, completely new phenomenon that we, preliminarily, study using strong simplifying assumptions are density-enhanced interactions of the flavor brane gauge field with holographically represented baryons. These seem to significantly affect the spectrum of vector and axial mesons and might lead to approximate chiral symmetry restoration in the lowest part of the spectrum, where the mesons start to qualitatively behave like collective excitations of the dense baryonic medium. We discuss the relevance of these effects for holographic searches of the quarkyonic phase and conclude with a discussion of various subtleties involved in constructing a mean-field holographic description of a dense baryonic medium.Comment: 31 pages, 16 figures; v2: inset plot in Fig. 10 removed, coloring in Fig. 13 fixed, typos fixed, matches published versio

Hybrid altimeter using a strapdown inertial navigation system

Hybrid radio and barometric altimeter using strapdown inertial navigation syste

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