251 research outputs found

    Coulomb and strong interactions in the final state of HBT correlations for L\'evy type source functions

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    We present detailed calculations about the expected shape of two-pion Bose-Einstein (or HBT) correlations in high energy heavy ion collisions that include a realistic treatment of final state Coulomb interaction as well as strong interactions (dominated by s-wave scattering). We assume L\'evy type source functions, a generalization that goes beyond the Gaussian approximation. Various recent experimental results found the use of such source types necessary to properly describe the shape of the measured correlation functions. We find that strong final state interactions may play an important role in the shape of the two-pion correlation functions, especially if one considers source parameters beyond the Gaussian HBT radii. Precise experimental determination of these source parameters (such as L\'evy stability exponent, correlation strength, etc.) seems to require the inclusion of the treatment of strong interaction not just for heavier particles (e.g. protons, lambdas) but also in case of two-pion measurements.Comment: 10 pages, 6 figure

    GREY MATTER AIROPHY IN PATIENTS SUFFERING FROM MULTIPLE SCLEROSIS

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    White matter lesions are defining characteristics of multiple sclerosis (MS), whereas grey matter involvement is a less recognised attribute. Recent investigations using dedicated imaging approaches have made it possible to depict cortical lesions. Additionally, grey matter atrophy may be estimated using various methods. Several studies have suggested that grey matter atrophy closely correlates to clinical disability. In this review we have collected information on grey matter atrophy in MS and the effect of disease modifying therapies upon brain atrophy

    Intrapulpal temperature changes during the cementation of ceramic veneers

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    Adhesive cementation of ceramic veneers may increase pulpal temperature (PT) due to the combined efect of heat generated by the curing unit and the exothermic reaction of the luting agent (LA). PT increase may induce pulpal damage. The aim was to determine the PT rise during the luting of ceramic veneers (CV) of diferent thicknesses with light- or dual-curing (LC, DC) adhesive cements as well as pre-heated restorative resin-based composites (PH-RBC). For this a thermocouple sensor was positioned in the pulp chamber of a prepared maxillary central incisor. LC, DC adhesive cements and PH-RBCs heated to 55 °C were used for the luting of CVs of 0.3, 0.5, 0.7, and 1.0 mm thicknesses. The exothermic reaction of LAs added signifcantly to the thermal efect of the curing unit. PT change ranged between 8.12 and 14.4 °C with the investigated combinations of LAs and ceramic thicknesses (p≤ 0.01). The increase was inversely proportional to the increasing CV thicknesses. The highest rise (p≤ 0.01) was seen with the polymerization of PH-RBCs. Temperature changes were predominantly infuenced by the composition of the LA, which was followed by CV thickness

    Nuclear dependence of the transverse single-spin asymmetry in the production of charged hadrons at forward rapidity in polarized p+pp+p, p+p+Al, and p+p+Au collisions at sNN=200\sqrt{s_{_{NN}}}=200 GeV

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    We report on the nuclear dependence of transverse single-spin asymmetries (TSSAs) in the production of positively-charged hadrons in polarized p+pp^{\uparrow}+p, p+p^{\uparrow}+Al and p+p^{\uparrow}+Au collisions at sNN=200\sqrt{s_{_{NN}}}=200 GeV. The measurements have been performed at forward rapidity (1.4<η<2.41.4<\eta<2.4) over the range of 1.8<pT<7.01.8<p_{T}<7.0 GeV/c/c and 0.1<xF<0.20.1<x_{F}<0.2. We observed a positive asymmetry ANA_{N} for positively-charged hadrons in \polpp collisions, and a significantly reduced asymmetry in pp^{\uparrow}+AA collisions. These results reveal a nuclear dependence of charged hadron ANA_N in a regime where perturbative techniques are relevant. These results provide new opportunities to use \polpA collisions as a tool to investigate the rich phenomena behind TSSAs in hadronic collisions and to use TSSA as a new handle in studying small-system collisions.Comment: 303 authors from 66 institutions, 9 pages, 2 figures, 1 table. v1 is version accepted for publication in Physical Review Letters. Plain text data tables for the points plotted in figures for this and previous PHENIX publications are (or will be) publicly available at http://www.phenix.bnl.gov/papers.htm

    Nuclear dependence of the transverse-single-spin asymmetry for forward neutron production in polarized pp++AA collisions at sNN=200\sqrt{s_{_{NN}}}=200 GeV

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    During 2015 the Relativistic Heavy Ion Collider (RHIC) provided collisions of transversely polarized protons with Au and Al nuclei for the first time, enabling the exploration of transverse-single-spin asymmetries with heavy nuclei. Large single-spin asymmetries in very forward neutron production have been previously observed in transversely polarized pp++pp collisions at RHIC, and the existing theoretical framework that was successful in describing the single-spin asymmetry in pp++pp collisions predicts only a moderate atomic-mass-number (AA) dependence. In contrast, the asymmetries observed at RHIC in pp++AA collisions showed a surprisingly strong AA dependence in inclusive forward neutron production. The observed asymmetry in pp++Al collisions is much smaller, while the asymmetry in pp++Au collisions is a factor of three larger in absolute value and of opposite sign. The interplay of different neutron production mechanisms is discussed as a possible explanation of the observed AA dependence.Comment: 315 authors, 8 pages, 4 figures, 1 table. v2 is version accepted for publication in Phys. Rev. Lett. Plain text data tables for the points plotted in figures for this and previous PHENIX publications are (or will be) publicly available at http://www.phenix.bnl.gov/papers.htm
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