1,979 research outputs found
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
Nuclear effects in photoproduction of heavy quarks and vector mesons in ultraperipheral PbPb and pPb collisions at the LHC
The comparison of photoproduction cross sections for and b-b(bar)
in PbPb and pPb collisions can give sensitivity to nuclear shadowing effects.
The photoproduction of vector mesons is even more sensitive to the underlying
gluon distributions. In this study we present the cross sections and rapidity
dependence of the photoproduction of heavy quarks and exclusive production of
vector mesons in ultraperipheral pPb and PbPb collisions at the Large Hadron
Collider at sqrt(s_NN)=5 TeV and sqrt(s_NN)=2.76J/\psi\Upsilon$ in
PbPb collisions in particular exhibit very good sensitivity to gluon shadowing.Comment: 4 pages, 4 figure
Synthesis and characterisation of some main-group compounds with bulky electron-withdrawring substituents
Several new group 13, 14 and 15 derivatives with the ligands 2,4,6-(CF(_3))(_3)C(_6)H(_2) (Ar), 2,6- (CF(_3))(_2)C(_6)H(_3) (Ar') and / or 2,4-(CF(_3))(_2)C(_6)H(_3) (Ar") have been prepared. They have been characterised by multinuclear NMR spectroscopy and, for all isolated compounds, by elemental analysis and, where possible, single crystal X-ray diffraction. Reaction of ArLi or the mixture Ar'Li/Ar"Li with BCI3 has led to the characterisation of several mono- and disubstituted compounds, but attempted substitution in AICI3 was unsuccessful. Reaction of EC1(_4) (E = Si, Ge, Sn) with the Ar'Li/Ar"Li mixture yielded predominantly the less sterically hindered disubstituted product Ar"(_2)ECl(_2) for E = Si and Ge but to Ar'(_2)ECl(_2) for E = Sn. In the case of B or Si, chlorine exchange is observed and Ar(_2)BF, Ar(_2)SiF(_2) and Ar'(_2)SiF(_2) have been synthesised. Ar(_2)SiF(_2) is the only product identified in the reaction of ArLi with SiC1(_4). Reaction of ArLi or the Ar'Li/Ar"Li mixture, in an appropriate ratio, with group 15 derivatives gave rise to several mono-or disubstituted compounds of the type ArEX(_2), Ar(_2)EX, Ar'EX(_2), Ar"EX(_2), Ar"(_2)EX and Ar'Ar"EX (E = P or As; X = H, CI or Br). (^19)F NMR spectra of Ar'Ar"EX show that, for the two ortho-CF(_3) groups of the Ar' moiety, there is free rotation of the aryl group around the central atom. A series of variable temperature studies has been carried out, and allowed the determination of the rotational energy barrier of the molecule. For the first time, the molecular structures of derivatives containing three fluoroxyl ligands have been determined (Ar"(_3)B and Ar'Ar"(_2)Sb).The synthesis of some new platinum complexes has been facilitated by reaction of phosphanes with the platinum dimer [(PtCl(_2)(Pet(_3))](_2) or [(PtBr(_2)(Pet(_3))](_2). Reactions of the platinum dimer with arsane derivatives have not been successful. Halogen exchange was observed between bromophosphane ligands and CI groups on the platinum. Attempts have been made to synthesise new P=E derivatives containing the electron- withdrawing substituents Ar or Ar' via reaction with the chlorine abstractor W(PMe(_3))(_6)- ArP=PAr and Ar'P=PAr' have been prepared. Synthesis of the first phosphaalkyne containing Ar or Ar' has been attempted by reacting a phosphaalkene with a Pt(0) species
CJK- Improved LO Parton Distributions in the Real Photon and Their Experimental Uncertainties
A new analysis of the radiatively generated, LO quark (u,d,s,c,b) and gluon
densities in the real, unpolarized photon, improved in respect to our paper
[1], is presented. We perform four new global fits to the experimental data for
F2^gamma, two using a standard FFNS approach and two based on ACOT(chi) scheme
[2], leading to the FFNS(CJK) and CJK models. We also present the analysis of
the uncertainties of the new CJK 2 parton distributions due to the experimental
errors, the very first such analysis performed for the photon. This analysis is
based on the Hessian method, for a comparison for chosen cross-sections we use
also the Lagrange method.Comment: Prepared for Photon 2003: International Conference on the Structure
and Interactions of the Photon (Including the 15th International Workshop on
Photon-Photon Collisions), Frascati (Italy), 7-11 April 2003; 10 pages, Latex
using espcrc2 style, 1 tex and 5 postscript figures; FORTRAN programs
available at http://www.fuw.edu.pl/~pjank/param.htm
Del Colegio de Boticarios de Barcelona al Real Colegio de Farmacia de San Victoriano: José Antonio Savall y Valldejuli (1752-1831)
[spa]El propĂłsito de esta tesis doctoral es conocer más a fondo la historia de los Ăşltimos boticarios barceloneses del siglo XVIII, en facetas todavĂa no estudiadas y al mismo tiempo la vida de la menestralĂa barcelonesa, en la cual estaban incluidos los maestros boticarios. Por otra parte, y siguiendo algunas de las directrices de estudio que se siguen en el Seminario de Historia de la Farmacia de Barcelona con respecto al Real Colegio de Farmacia de San Victoriano y de la Facultad de Farmacia, convenĂa conocer con detalle a alguno de los profesores del citado Colegio, y nada mejor que analizar la vida y trayectoria de don JosĂ© Antonio Savall y Valldejuli (1752-1831) para conjuntar ambas ideas, tanto por lo que atañe a la vida barcelonesa finisecular del dieciocho como por su actuaciĂłn como profesor. Es sabido que un grupo de boticarios catalanes pretendieron crear unos estudios generales de Farmacia en Barcelona a mediados del siglo XVIII, y tambiĂ©n que la AdministraciĂłn central (que recibiĂł esos proyectos con atenciĂłn pero con lentitud) los incorporĂł definitivamente a unas enseñanzas que se impartirĂan en todo el paĂs a travĂ©s de determinados Colegios de carácter oficial. Todos estos cambios se encuentran presentes en la figura excepcional de Savall, profesor de la Facultad Reunida, primer Ayudante del EjĂ©rcito de Operaciones durante la Guerra de la Independencia, Doctor en Farmacia y Catedrático del Real Colegio de Farmacia de San Victoriano. En esta tesis hemos buscado establecer un jucio crĂtico y objetivo de la figura de Savall, en primer lugar como barcelonĂ©s, asĂ como las relaciones con su familia, con la Iglesia, con el Colegio de Boticarios, con la Real Academia de Ciencias Naturales y Artes de Barcelona, asĂ como su relaciĂłn como farmacĂ©utico en la Guerra de la Independencia y como profesor en el Real Colegio. Para ello hemos podido contar con la documentaciĂłn, hasta ahora inĂ©dita, hallada en distintos archivos de la ciudad, principalmente del Archivo General de Protocolos, del que se han consultado expedientes relacionados con una cincuentena de notarios. Dado que la mayorĂa de los documentos se hallaban escritos en catalán de aquella Ă©poca, se ha realizado la transcripciĂłn, traducciĂłn y estudio de los mismos. En su vertiente como farmacĂ©utico, ha sido especialmente interesante el hallazgo de un manuscrito en el Archivo de la Biblioteca de la Universidad de Barcelona, numerado con el 1777, que se titula “Llibre de Medicinas per lo Collegi de P.P. Trinitaris Catalçats. Barcelona 1778”, del que se realiza en esta tesis un estudio detallado, incluyendo la transcripciĂłn de algunas de las fĂłrmulas que contiene
L'apotecari catalĂ Josep Antoni Savall i la seva reivindicaciĂł d'una nova farmacopea a la ciutat de Barcelona i principat de Catalunya l'any 1788
En aquesta comunicació es dóna a conèixer la tasca realitzada per l’apotecari Josep Antoni Savall, considerat figura rellevant en la transició de l’apotecari al farmacèutic, aixà com la seva reivindicació d’una farmacopea nova a la ciutat de Barcelona i principat de Catalunya a l’any 1788 després de més de cent anys de l’edició de la Farmacopea Catalana de Joan d’Alós (1686) i de dos-cents de la última edició de la “Concordia Apothecariorum Bardrinonensium “(1587).En esta comunicación se da a conocer la labor realizada por el boticario Joan Antoni Savall, considerado figura relevante en la transición del boticario al farmacéutico, asà como su reivindicación de una nueva farmacopea en la Ciudad de Barcelona y Principado de Catalunya en el año 1788, después de más de cien años de la Farmacopea Catalana de Juan de Alós (1686) y doscientos de la última edición de la “Concordia Apothecariorum Bardrinonensium” (1587)
Controlled Flavour Changing Neutral Couplings in Two Higgs Doublet Models
We propose a class of Two Higgs Doublet Models where there are Flavour
Changing Neutral Currents (FCNC) at tree level, but under control due to the
introduction of a discrete symmetry in the full Lagrangian. It is shown that in
this class of models, one can have simultaneously FCNC in the up and down
sectors, in contrast to the situation encountered in BGL models. The intensity
of FCNC is analysed and it is shown that in this class of models one can
respect all the strong constraints from experiment without unnatural
fine-tuning. It is pointed out that the additional sources of flavour and CP
violation are such that they can enhance significantly the generation of the
Baryon Asymmetry of the Universe, with respect to the Standard Model.Comment: 29 pages, 3 figure
Symmetry Constrained Two Higgs Doublet Models
We study Two-Higgs-Doublet Models (2HDM) where Abelian symmetries have been
introduced, leading to a drastic reduction in the number of free parameters in
the 2HDM. Our analysis is inspired in BGL models, where, as the result of a
symmetry of the Lagrangian, there are tree-level scalar mediated
Flavour-Changing-Neutral-Currents, with the flavour structure depending only on
the CKM matrix. A systematic analysis is done on the various possible schemes,
which are classified in different classes, depending on the way the extra
symmetries constrain the matrices of couplings defining the flavour structure
of the scalar mediated neutral currents. All the resulting flavour textures of
the Yukawa couplings are stable under renormalisation since they result from
symmetries imposed at the Lagrangian level. We also present a brief
phenomenological analysis of the most salient features of each class of
symmetry constrained 2HDM.Comment: 30 pages, 5 Table
Estudi de l'especialitat farmacèutica ferroi-iodose-Ferrer en el context de la sanitat del segle XX
L'objectiu d'aquesta comunicació és donar a conèixer l'estudi de l'evolució de l'especialitat ferro-iodose-ferrer dins el context històric en el que va començar el seu desenvolupament. Destaca per ésser una especialitat premiada amb la medalla d'or de l'Exposició Internacional de Barcelona, l'any 1929
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