Search results for "freedom"
showing 10 items of 458 documents
Quark and gluon distributions and $\alpha_{s}$ from nucleon structure functions at low $x$
1993
Abstract The Q2 dependence of the structure functions F2p and F2d recently measured by the NMC is compared with the predictions of perturbative QCD at next-to-leading order. Good agreement is observed, leading to accurate determinations of the quark and gluon distributions in the range 0.008 ⩽ × ⩽ 0.5. The strong coupling constant is measured from the low x data; the result agrees with previous determinations.
Electromagnetic structure of few-nucleon ground states
2015
Experimental form factors of the hydrogen and helium isotopes, extracted from an up-to-date global analysis of cross sections and polarization observables measured in elastic electron scattering from these systems, are compared to predictions obtained in three different theoretical approaches: the first is based on realistic interactions and currents, including relativistic corrections (labeled as the conventional approach); the second relies on a chiral effective field theory description of the strong and electromagnetic interactions in nuclei (labeled $\chi$EFT); the third utilizes a fully relativistic treatment of nuclear dynamics as implemented in the covariant spectator theory (labeled…
mixing in the weak-gauged U(4)L⊗U(4)R chiral lagrangian model
1998
Abstract The D0– D 0 mixing is analyzed in a weak gauged U(4)L⊗U(4)R chiral lagrangian model where the electroweak interaction is introduced as a gauge theory over the meson degrees of freedom. This model allows a particular realization of the G.I.M. mechanism and then could be useful in the study of processes where G.I.M. suppression is effective. As a test of the model we have also analyzed the K0– K 0 mixing. We find ΔmK in good agreement with the experimental result and we show that the D0– D 0 mixing is very much suppressed in agreement with previous estimates in the Heavy Quark expansion framework.
Quark degrees of freedom in hadronic systems
2000
Quantum Chromodynamics (QCD) is the theory of the strong interactions. We review descriptions of hadronic systems motivated by QCD, analyzing the recent controversy between gluonic and bosonic degrees of freedom under the prism of the Cheshire Cat Principle. Our analysis leads to an optimal scheme to study hadronic properties. We proceed to extend this low energy descriptions to the deep inelastic regime.
Quark gap equation within the analytic approach to QCD
2005
The compatibility between the QCD analytic invariant charge and chiral symmetry breaking is examined in detail. The coupling in question incorporates asymptotic freedom and infrared enhancement into a single expression, and contains only one adjustable parameter with dimension of mass. When inserted into the standard form of the quark gap-equation it gives rise to solutions displaying singular confining behavior at the origin. By relating these solutions to the pion decay constant, a rough estimate of about 880 MeV is obtained for the aforementioned mass-scale.
Representations and derivations of quasi ∗-algebras induced by local modifications of states
2009
Abstract The relationship between the GNS representations associated to states on a quasi ∗-algebra, which are local modifications of each other (in a sense which we will discuss) is examined. The role of local modifications on the spatiality of the corresponding induced derivations describing the dynamics of a given quantum system with infinite degrees of freedom is discussed.
Reliģiski-filozofiski raksti, 20
2016
Katrā no rakstiem, kas publicēti šajos "Reliģiski-filozofiskos rakstos", šķiet, iespējams saskatīsim gan pagātnes sprostā patvērušos brīvību ar tās apreibinošajās ilūzijām par neatkarību ārpus sprosta, gan nojaust neatrisināmo un reizēm iznīcinošo dilemmu starp gara un reālo pasauli, starp spēli un brīdi, kad spēle beidzas. Piemēram, par pagātnē iesprostotas virtuālās pasaules konstruēšanu, kuras brīvībā izlaušanās mērāma iznīcinātu dzīvību tūkstošos, mums stāsta Māris Kūlis savā rakstā “Islāma valsts propaganda digitālajā laikmetā”. Uzsverot, ka Islāma valsts īstenotais militārais un ārkārtīgi agresīvais džihāds ar vēl nepieredzētām sekmēm ir izveidojis sinkrētisku reliģiskās degsmes un mū…
A Hebbian approach to complex-network generation
2011
Through a redefinition of patterns in an Hopfield-like model, we introduce and develop an approach to model discrete systems made up of many, interacting components with inner degrees of freedom. Our approach clarifies the intrinsic connection between the kind of interactions among components and the emergent topology describing the system itself; also, it allows to effectively address the statistical mechanics on the resulting networks. Indeed, a wide class of analytically treatable, weighted random graphs with a tunable level of correlation can be recovered and controlled. We especially focus on the case of imitative couplings among components endowed with similar patterns (i.e. attribute…
Il sigillo spezzato. Moderno e antimoderno nell’interpretazione habermasiana di Nietzsche
2022
Starting from the analysis of the concept of modernity, this contribution focuses on Habermas' critique of Nietzsche. In particular on the idea that Nietzsche is a break point with modernity and the basis of the post-modern. On the line of defense of modernity and its universalistic normative contents, Habermas re-proposes the transcendental in an anti-relativistic sense. The explosive power of "philosophy with the hammer" and the "total critique of reason" undermine the emancipatory demands of modernity with conservative effects. According to Habermas, the radical critique of truth demolishes itself and the claim to validity. The modern, on the other hand, can be reformed through a model o…
The influence of internal degrees of freedom on the unimolecular decay of the molecule–cluster compound Au8+CH3OH
2002
Time-resolved photodissociation measurements of the sequential reaction Au8+CH3OH→Au8+→Au7+ and the direct reaction Au8+→Au7+ have been performed for several excitation energies. The production rates and yields of the final state Au7+ in the sequential process are strongly influenced by the excitation energy deposited into the evaporated methanol molecule during the initial fragmentation step. Both the rate constants and yields can be fitted with a single parameter, the cluster–methanol binding energy.