251 research outputs found
Coulomb and strong interactions in the final state of HBT correlations for L\'evy type source functions
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
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
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 , Al, and Au collisions at GeV
We report on the nuclear dependence of transverse single-spin asymmetries
(TSSAs) in the production of positively-charged hadrons in polarized
, Al and Au collisions at
GeV. The measurements have been performed at forward
rapidity () over the range of GeV and
. We observed a positive asymmetry for
positively-charged hadrons in \polpp collisions, and a significantly reduced
asymmetry in + collisions. These results reveal a nuclear
dependence of charged hadron 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 collisions at GeV
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 collisions at
RHIC, and the existing theoretical framework that was successful in describing
the single-spin asymmetry in collisions predicts only a moderate
atomic-mass-number () dependence. In contrast, the asymmetries observed at
RHIC in collisions showed a surprisingly strong dependence in
inclusive forward neutron production. The observed asymmetry in Al
collisions is much smaller, while the asymmetry in 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 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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