1,721,211 research outputs found
Neutron orbital structure from generalized parton distributions of 3He
No full textThe generalized parton distribution H and E of the 3He nucleus, which can be measured in hard exclusive processes such as coherent deeply virtual Compton scattering, are thoroughly analyzed in impulse approximation, within the Av18 interaction. It is found that their sum, at low momentum transfer, is dominated to a large extent by the neutron contribution: the peculiar spin structure of 3He makes this target unique for the extraction of the neutron information. This observation allows access, in dedicated experiments, to the orbital angular momentum of the partons in the neutron
Scalar and tensor glueballs as gravitons
No full textThe bottom-up approach of the AdS/CFT correspondence leads to the study of field equations in an AdS5 background and from their solutions to the determination of the hadronic mass spectrum. We extend the study to the equations of AdS5 gravitons and determine from them the glueball spectrum. We propose an original presentation of the results which facilitates the comparison of the various models with the spectrum obtained by lattice QCD. This comparison allows to draw some phenomenological conclusions
Spinning Q–balls in Abelian Gauge Theories with positive potentials: existence and non existence
No full textWe study the existence of cylindrically symmetric electro-magnetostatic solitary waves for a system of a nonlinear Klein–Gordon equation coupled with Maxwell’s equations in presence of a positive mass and of a nonnegative nonlinear potential. Nonexistence results are provided as well
Relativistic effects in model calculations of double parton distribution functions
No full textpeer reviewedIn this paper we consider double-parton distribution functions (dPDFs), which are the main nonperturbative ingredients appearing in the double-parton scattering cross section formula in hadronic collisions. By using recent calculation of dPDFs by means of constituent quark models within the so-called light-front approach, we investigate the role of relativistic effects on dPDFs. We find, in particular, that the so-called Melosh operators, which allow us to properly convert the LF spin into the canonical one and incorporate a proper treatment of boosts, produce sizeable effects on dPDFs. We discuss specific partonic correlations induced by these operators in the transverse plane which are relevant to the proton structure, and we study under which conditions these results are stable against variations in the choice of the proton wave function. © 2017 American Physical Society
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
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