1,352 research outputs found
Strangeness and Particle Freeze-out in Nuclear Collisions at 14.6 Gev a
We study the chemical conditions at freeze-out associated with the production
of strange-particles in Si-Au collisions at 14.6 GeV A. We obtain freeze-out
chemical potentials and temperature, and determine the entropy as well as the
final particle abundance. We also consider in detail the alternative evolution
scenarios involving the hadronic gas and the deconfined phase.Comment: 12 pages, LaTeX, 3 postscript figure
Interpretations of suppression
We review the two main interpretations of suppression proposed in
the literature. The phase transition (or deconfining) scenario assumes that
below some critical value of the local energy density (or of some other
geometrical quantity which depends both on the colliding systems and on the
centrality of the collision), there is only nuclear absorption. Above this
critical value the absorptive cross-section is taken to be infinite, i.e. no
can survive in this hot region. In the hadronic scenario the
dissociates due both to nuclear absorption and to its interactions with
co-moving hadrons produced in the collision. No discontinuity exists in
physical observables. We show that an equally good description of the present
data is possible in either scenario.Comment: 12 pages, LaTeX, uses epsfig and ioplppt; review talk given by A.
Capella at the International Symposium on Strangness in Quark Matter,
Santorini (Greece), April 1997; Figs. 1 and 2 not available but can be found
in Refs. 13 and 6 respectivel
What information can we obtain from the yield ratio in heavy-ion collisions ?
The recently reported data on the yield ratio in central
rapidity region of heavy-ion collisions are analyzed by theoretical formula
which accounts for Coulomb interaction between central charged fragment (CCF)
consisting of nearly stopped nucleons with effective charge
Z_{\mbox{\scriptsize eff}} and charged pions produced in the same region of
the phase space. The Coulomb wave function method is used instead of the usual
Gamow factor in order to account for the finite production range of pions,
. For Gaussian shape of the pion production sources it results in a
quasi-scaling in and Z_{\mbox{\scriptsize eff}} which makes
determination of parameters and Z_{\mbox{\scriptsize eff}} from the
existing experimental data difficult. Only sufficiently accurate data taken in
the extreme small - region, where this
quasi-scaling is broken, could be used for this purpose.Comment: 7 pages, Latex type, 8 figure
On the angular momentum dependence of nuclear level densities
Angular momentum dependence of nuclear level densities at finite temperatures
are investigated in the static path approximation(SPA) to the partition
function using a cranked quadrupole interaction Hamiltonian in the following
three schemes: (i) cranking about x-axis, (ii) cranking about z-axis and (iii)
cranking about z-axis but correcting for the orientation fluctuation of the
axis. Performing numerical computations for an and a shell nucleus,
we find that the x-axis cranking results are satisfactory for reasonably heavy
nuclei and this offers a computationally faster method to include the angular
momentum dependence at high temperatures in the SPA approach. It also appears
that at high spins inclusion of orientation fluctuation correction would be
important.Comment: 19 Latex pages, 9 figures(available upon request
A Psychometric Study of a Trait and State Assessment of Sexual Pleasure - The Amsterdam Sexual Pleasure Inventory.
We studied the Amsterdam Sexual Pleasure Inventory's (1.0) psychometric properties. The ASPI, a revised self-report battery designed to measure domains of state and trait sexual pleasure in diverse gender, sex, and relationship populations, is based on a recently proposed conceptual framework of sexual pleasure. We collected quantitative (nâ=â1371) and qualitative data (nâ=â637) using a cross-sectional multi-method design targeting the general (German-speaking) population. After pre-processing, we conducted analyses on a sample of nâ=â706 participants. The theory-based 5-factor exploratory structural equation model and the principal component analyses of the two general exploratory index-scales showed good and acceptable structural validity evidence respectively. Measurement invariance was confirmed separately for male and female participants and for those with sexually functional-scoring and dysfunctional-scoring levels. Coefficient omega indicated that all scales, except those of one facet, showed acceptable to very good internal consistency. The ASPI's convergent and discriminant associations with sexological and psychological constructs demonstrated good overall construct validity. Participants understood the items as intended and felt that the ASPI covered relevant facets of sexual pleasure. The ASPI might help understand how individuals differ in experiencing sexual pleasure and how different contexts enable some people to experience pleasure while disadvantaging others
The High E_T Drop of J/psi to Drell-Yan Ratio from the Statistical c anti-c Coalescence Model
The dependence of the J/psi yield on the transverse energy E_T in heavy ion
collisions is considered within the statistical c anti-c coalescence model. The
model fits the NA50 data for Pb+Pb collisions at the CERN SPS even in the
high-E_T region (E_T > 100 GeV). Here E_T-fluctuations and E_T-losses in the
dimuon event sample naturally create the celebrated drop in the J/psi to
Drell-Yan ratio.Comment: 14 pages, REVTeX, 1 PS-figure. v2: References are corrected and
update
Open Charm Enhancement in Pb+Pb Collisions at SPS
The statistical coalescence model for the production of open and hidden charm
is considered within the canonical ensemble formulation. The data for the
J/\psi multiplicity in Pb+Pb collisions at 158 A GeV are used for the model
prediction of the open charm yield. We find a strong enhancement of the open
charm production, by a factor of about 2--4, over the standard hard-collision
model extrapolation from nucleon-nucleon to nucleus-nucleus collisions. A
possible mechanism of the open charm enhancement in A+A collisions at the SPS
energies is proposed.Comment: 4 pages, Late
Open and Hidden Charm Production in Heavy Ion Collisions at Ultrarelativistic Energies
We consider the production of the open charm and J/psi mesons in heavy ion
collisions at BNL RHIC. We discuss several recently developed pictures for
J/psi production and argue that a measurement at RHIC energies is crucial for
disentangling these different descriptions.Comment: 19 pages, Latex, 5 PS-figures. v3: Fig.6 is adde
- âŠ