1,721,217 research outputs found
Parton intrinsic motion in inclusive particle production: unpolarized cross sections, single spin asymmetries, and the Sivers effect
No full textThe relevance of intrinsic (or primordial) transverse momentum of partons in the inclusive production of particles at high energy and moderately large p(T) has been known for a long time, beginning with Drell-Yan and diphoton processes, and continuing with photon and meson production in hadronic collisions. In view of its renewed interest in the context of polarized processes and single spin asymmetries we perform, in the framework of perturbative QCD with the inclusion of spin and k(perp)-effects, a detailed analysis of several such processes in different kinematical situations. We show that the inclusion of these effects leads, at the level of accuracy reachable in this approach, to an overall satisfactory agreement between theoretical predictions and experimental unpolarized data, thus giving support to the study of spin effects and single spin asymmetries within the same scheme. We present results for transverse single spin asymmetries, generated by the so-called Sivers effect, in inclusive pion and photon production in proton-proton collisions. We compare our results with the available experimental data and with previous results obtained using simplified versions of this approach
Azimuthal and single spin asymmetries in hard scattering processes
No full textIn this article we review the present understanding of azimuthal and single spin asymmetries for inclusive and semi-inclusive particle production in unpolarized and polarized hadronic collisions at high energy and moderately large transverse momentum. After summarizing the experimental information available, we discuss and compare the main theoretical approaches formulated in the framework of perturbative QCD. We then present in some detail a generalization of the parton model with inclusion of spin and intrinsic transverse momentum effects. In this context, we extensively discuss the phenomenology of azimuthal and single spin asymmetries for several processes in different kinematical configurations. A comparison with the predictions of other approaches, when available, is also given. We finally emphasize some relevant open points and challenges for future theoretical and experimental investigation
IMMIGRAZIONE E SALUTE. LA SALUTE RIPRODUTTIVA DELLE DONNE IMMIGRATE
No full textThe women’s population was considered to think about the health issues of the immigrant population in Sardinia. For physiological reasons such as pregnancy, childbirth, child care women access to health services more than men do.
The data of women admitted to the Obstetrics clinic of the University of Cagliari from 2000 to 2008 were examined. The data were divided between Western and non-Western population.
The performed processing show that non-Western population differs from the Western for several variables both pertaining to vital statistics (age, social background) and obstetric (number of children, age of first pregnancy, reason of hospitalization among which the increased use of Ivg and the lower need for cesarean section come out). Differences emerge naturally by nationality (women from Eastern Europe, Chinese, Gypsies, African women and women from Central and South America were considered separately) connectable to the type of migration path, whether more or less stable
3D point cloud reconstruction from single plenoptic image
No full textNovel plenoptic cameras sample the light field crossing the main camera lens. The information available in a plenoptic image must be processed, in order to create the depth map of the scene from a single camera shot. In this paper a novel algorithm, for the reconstruction of 3D point cloud of the scene from a single plenoptic image, taken with a consumer plenoptic camera, is proposed. Experimental analysis is conducted on several test images, and results are compared with state of the art methodologies. The results are very promising, as the quality of the 3D point cloud from plenoptic image, is comparable with the quality obtained with current non-plenoptic methodologies, that necessitate more than one image
Collins and Sivers effects in p(up arrow) p --> jet pion X: Universality and process dependence
No full textIn this paper we briefly review the transverse momentum dependent generalized parton model
and its application to the study of azimuthal asymmetries in the distribution of leading hadrons (mainly pions) inside large transverse momentum jets inclusively produced in polarized proton proton
collisions. We put particular emphasis on the phenomenological interest of these observables, in combination with similar asymmetries measured in semi-inclusive deeply inelastic scattering,
Drell-Yan processes and e+e- collisions, for the study of the universality properties of the transverse momentum dependent parton distribution and fragmentation functions. We present results for RHIC
kinematics at center-of-mass energies sqrt(s) = 200 and 500 GeV, for central and mainly forward jet rapidities, in particular for the Sivers distribution and the Collins fragmentation function, that are believed to be responsible for many of the largest asymmetries measured in the last years. We also briefly discuss the case of inclusive jet production and recent phenomenological applications of other theoretical approaches, like the colour gauge invariant generalized parton model and the collinear
twist-three approach, aiming at clarifying the issues of the universality and process dependence of transverse momentum dependent functions
Probing TMDs through azimuthal distributions of pions inside a jet in hadronic collisions
No full textThe azimuthal distributions around the jet axis of leading pions produced in the jet fragmentation process in pp collisions are studied within the framework of the so-called generalized parton model. The observable leading-twist azimuthal asymmetries are estimated in kinematic configurations presently investigated at RHIC. It is shown how the main contributions coming from the Collins and Sivers effects can be disentangled. In addition, a test of the process dependence of the Sivers function is provided
Closo-Hydroborate Sodium Salts as an Emerging Class of Room-Temperature Solid Electrolytes
Full text linkNa-based hydroborates, such as NaCB9H10, Na2B10H10, NaCB11H12, and Na2B12H12, are known for their high ionic conductivity above a phase transition, usually far from room temperature. Here, a systematic investigation to suppress this phase transition and thus to stabilize novel crystal structures is conducted by means of anion mixing. The obtained compounds crystallize either with hexagonal and cubic close packed (hcp and ccp) or body-centered cubic (bcc) arrangement of anions without polymorphic evolution in the temperature range 100 < T < 700 K. The high symmetry and the configurational ionic disorder, which characterize all crystals, give room-temperature Na+ conductivity close or above 1 mS cm−1. Finally, high oxidative electrochemical stability between 3 and 4 V versus Na+/Na results from the aromatic nature of the boron cage, making Na-based hydroborates potentially suitable as efficient solid electrolytes for next-generation, high-voltage, Na-ion batteries. Various drawbacks limit the development of solid electrolytes for sodium-based batteries as cheap and efficient alternatives to conventional Li-ion batteries. Brighi et al. present a strategy to stabilize hydroborate-based compounds with high sodium mobility, large electrochemical and thermal stability, and excellent mechanical properties
Metal hydroborates: From hydrogen stores to solid electrolytes
Full text linkThe last twenty years of an intense research on metal hydroborates as solid hydrogen stores and solid electrolytes are reviewed. It is shown that from the most promising application in hydrogen storage due to their high gravimetric and volumetric capacities, the focus has moved to solid electrolytes due to high cation mobility in disordered structures with rotating or tumbling anions-hydroborate clusters. Various strategies of overcoming the strong covalent bonding of hydrogen in hydroborates for hydrogen storage and disordering their structures at room temperature for solid electrolytes are discussed. The important role of crystal chemistry and crystallography knowledge in material design can be read in the cited literature
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