HERAFitter Alekhin, S.; Behnke, O.; Belov, P. ...
The European physical journal. C, Particles and fields,
07/2015, Letnik:
75, Številka:
7
Journal Article
Recenzirano
Odprti dostop
HERAFitter is an open-source package that provides a framework for the determination of the parton distribution functions (PDFs) of the proton and for many different kinds of analyses in Quantum ...Chromodynamics (QCD). It encodes results from a wide range of experimental measurements in lepton–proton deep inelastic scattering and proton–proton (proton–antiproton) collisions at hadron colliders. These are complemented with a variety of theoretical options for calculating PDF-dependent cross section predictions corresponding to the measurements. The framework covers a large number of the existing methods and schemes used for PDF determination. The data and theoretical predictions are brought together through numerous methodological options for carrying out PDF fits and plotting tools to help to visualise the results. While primarily based on the approach of collinear factorisation, HERAFitter also provides facilities for fits of dipole models and transverse-momentum dependent PDFs. The package can be used to study the impact of new precise measurements from hadron colliders. This paper describes the general structure of HERAFitter and its wide choice of options.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
The synthesis and structural characterization of a series of supramolecular complexes of bicyclic cationic pyridine-fused 1,2,4-selenodiazoles with various anions is reported. The binding of ...trifluoroacetate, tetrachloroaurate, tetraphenylborate, perrhenate, and pertechnetate anions in the solid state is regarded. All the anions interact with selenodiazolium cations exclusively via a pair of “chelating” Se⋯O and H⋯O non-covalent interactions, which make them an attractive, novel, non-classical supramolecular recognition unit or a synthon. Trifluoroacetate salts were conveniently generated via novel oxidation reaction of 2,2′-dipyridyl diselenide with bis(trifluoroacetoxy)iodo)benzene in the presence of corresponding nitriles. Isolation and structural characterization of transient 2-pyridylselenyl trifluoroacetate was achieved. X-ray analysis has demonstrated that the latter forms dimers in the solid state featuring very short and strong Se⋯O and Se⋯N ChB contacts. 1,2,4-Selenodiazolium trifluoroacetates or halides show good solubility in water. In contrast, (AuCl4)−, (ReO4)−, or (TcO4)− derivatives immediately precipitate from aqueous solutions. Structural features of these supramolecular complexes in the solid state are discussed. The nature and energies of the non-covalent interactions in novel assembles were studied by the theoretical methods. To the best of our knowledge, this is the first study that regards perrhenate and pertechnetate as acceptors in ChB interactions. The results presented here will be useful for further developments in anion recognition and precipitation involving cationic 1,2,4-selenodiazoles.
Recent measurements of the
W
-boson charge asymmetry and of the
Z
-boson production cross sections, performed at the Tevatron collider in Run II by the D0 and CDF collaborations, are studied using ...the HERAFitter framework to assess their impact on the proton parton distribution functions (PDFs). The Tevatron measurements, together with deep-inelastic scattering data from HERA, are included in a QCD analysis performed at next-to-leading order, and compared to the predictions obtained using other PDF sets from different groups. Good agreement between measurements and theoretical predictions is observed. The Tevatron data provide significant constraints on the
d
-valence quark distribution.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
The series of benzylic-substituted 1,2,4-selenodiazolium salts were prepared via cyclization reaction between 2-pyridylselenyl chlorides and nitriles and fully characterized. Substitution of the Cl ...anion by weakly binding anions promoted the formation supramolecular dimers featuring four center Se
N
chalcogen bonding and two antiparallel selenium⋯π interactions. Chalcogen bonding interactions were studied using density functional theory calculations, molecular electrostatic potential (MEP) surfaces, the quantum theory of atoms-in-molecules (QTAIM), and the noncovalent interaction (NCI) plot. The investigations revealed fundamental role of the selenium⋯π contacts that are stronger than the Se⋯N interactions in supramolecular dimers. Importantly, described herein, the benzylic substitution approach can be utilized for reliable supramolecular dimerization of selenodiazolium cations in the solid state, which can be employed in supramolecular engineering.
In this work, epoxy diane oligomer ÉD-20 is used to form nanocomposite materials, polyethylene polyamine is used as a hardener, ultradispersed diamond with a particle size of 4–6 nm is used as a ...filler. The epoxy diane resin ÉD-20 was heated to 353 K. Then the ÉD-20 oligomer and the nanofiller were subjected to hydrodynamic mixing and subsequent ultrasonic treatment of the obtained composition. The effect of the concentration of diamond nanoparticles on the adhesion properties of composites was studied. The adhesion pull strength of materials was studied by measuring breaking stresses of cylindrical specimens glued by the nanocomposite adhesive. The adhesive shear strength was evaluated by the breaking stress of the lap joints of flat metal specimens glued by the nanocomposite adhesive. In both types of specimens, the glued sections had the same area. It has been found that the incorporation of nanoparticles in the concentration from 0.010 to 0.025 parts by weight per 100 parts by weight of ÉD-20 epoxy oligomer yields the adhesive pull strength of 25.0–26.3 MPa. The optimal concentration increases the latter value by a factor of 1.5 (to 34.3 MPa) and the adhesive shear strength – by a factor of 1.3 (to 10.8 MPa). The further increase in the concentration (0.075–1.0 parts by weight) is shown to deteriorate the adhesion strength. The nanocomposite coating–metal substrate bond breaking surface has been investigated. It is experimentally proved that the coatings with the cohesive nature of failure have the maximum adhesive pull strength, while those with the mixed (adhesive-cohesive) mode of failure exhibit an improved adhesive shear strength.
The series of substituted 1,2,4-selenodiazolium tetraphenylborate complexes were synthesized via cyclization between 2-pyridylselenylchloride, followed by the anion metathesis, and fully ...characterized. The utilization of tetraphenylborate anion, a strong π-electron donor via its phenyl rings, promoted the formation of assemblies exhibiting selenium–π interactions. The chalcogen bonding (ChB) interactions involving the π-systems of the tetraphenylborate anion were studied using density functional theory (DFT) calculations, where “mutated” anions were used to estimate the strength of the Se···π chalcogen bonds. Moreover, molecular electrostatic potential (MEP) surfaces were used to investigate the electron-rich and poor regions of the ion pairs. The quantum theory of atoms-in-molecules (QTAIM) and the noncovalent interaction (NCI) plot methods based on the topology of the electron density were used and combined to characterize the ChBs. The investigation reported herein disclosed that the formation of symmetrical dimers can be broken by the introduction of a stronger π-acceptor and, consequently, forming stronger Se···π contacts with selenodiazolium cations.
Методом оптичної мікроскопії досліджено структуру зламу композитних матеріалів із різним вмістом нанодисперсного фулерену С60. Як основний компонент для зв'язувача під час формування епоксидних ...композитів вибрано епоксидний діановий олігомер марки ЕД-20, який характеризується поліпшеною адгезійною міцністю, незначною усадкою і технологічністю після нанесення на довговимірні поверхні складного профілю. Для зшивання епоксидних композицій використано твердник поліетиленполіамін ПЕПА, що дає змогу затверджувати матеріали за кімнатних температур. Для підвищення властивостей композитних матеріалів використано фулерен С60здисперсністю 5 нм. Композитний матеріал із нанодисперсним наповнювачем формували за технологією, яка передбачала попереднє ультразвукове диспергування композиції до введення твердника за оптимальних температурно-часових режимів. Показано, що структура зламу матриці характеризується хаотичним напрямком поширення тріщини, що свідчить про нестабільні значення властивостей у процесі експлуатації. Відповідно встановлено оптимальний вміст нанодисперсних часток фулерену С60 в епоксидному зв'язувачі, який становить q = 0,025…0,050 мас. ч. При цьому спостережено помірну в'язкість поверхні руйнування композитного матеріалу, що нівелює багатовекторне поширення тріщин в об'ємі полімеру, а отже, дає змогу експлуатувати розроблені матеріали без зміни їх властивостей впродовж тривалого часу.
New features of the MCSANC v.1.20 program, a Monte Carlo tool for calculation of the next-to-leading order electroweak and QCD corrections to various Standard Model processes, have been presented. ...The extensions concern implementation of Drell–Yan-like processes and include a systematic treatment of the photon-induced contribution in proton–proton collisions and electroweak corrections beyond the NLO approximation. There are also technical improvements such as calculation of the forward–backward asymmetry for the neutral current Drell–Yan process. The updated code is suitable for studies of the effects due to EW and QCD radiative corrections to Drell–Yan (and several other) processes at the LHC and for forthcoming high-energy proton–proton colliders.
A compact and finely grained sandwich calorimeter is designed to instrument the very forward region of a detector at a future e super(+)e super(-) collider. The calorimeter will be exposed to low ...energy e super(+)e super(-) pairs originating from beamstrahlung, resulting in absorbed doses of about one MGy per year. GaAs pad sensors interleaved with tungsten absorber plates are considered as an option for this calorimeter. Several Cr-doped GaAs sensor prototypes were produced and irradiated with 8.5-10MeV electrons up to a dose of 1.5MGy. The sensor performance was measured as a function of the absorbed dose.
The mechanical characteristics of epoxy nanocomposites with ultradisperse diamond particles as a filler are investigated. It is shown that the addition of the particles of ultradisperse diamond at a ...concentration of 0.05 part by weight (pt.wt.) per 100 pt.wt. of the epoxy binder, increases the most the bending strength and reduces residual stresses in the composite. Moreover, the elastic modulus of the composite material increases. The chemical activity of the nanofiller particle surface resulting in the enhancement of physical and mechanical properties in the cross-linking of epoxy-based composite materials is determined by IR-spectrum analysis. The fracture surfaces of nanocomposite materials were investigated using optical microscopy. Based on the analysis of the topology of fracture surfaces of nanocomposite materials, it was revealed that the structure is ordered, with no visible inclusions, which is indicative of the maximum degree of cross-linking of composite materials with a concentration of ultradisperse diamond of 0.05 pt.wt. A uniform stress distribution in the volume of the investigated materials is indicative of the thermodynamic equilibrium in systems after cross-linking.
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