1,090 research outputs found
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
Jet quenching in thin plasmas
We investigate the energy loss of quarks and gluons produced in hard
processes resulting from final state rescatterings in a finite quark-gluon
plasma. The angular distribution of the soft gluon bremsstrahlung induced by
n_s=1 rescatterings in the plasma is computed in the Gyulassy-Wang model.
Special focus is on how the interference between the initial hard radiation
amplitude, the multiple induced Gunion-Bertsch radiation amplitudes, and gluon
rescattering amplitudes modifies the classical parton cascade results.Comment: 4 pages in Latex and 3 EPS figures, Proceedings of the Quark
Matter'99 Conference, 10-15 May, 1999, Torin
Cronin Effect at Different Rapidities at RHIC
Calculations of the nuclear modification factor, R_dAu, for pi^0 production
in dAu collisions at s_NN^1/2 = 200 GeV are presented. The applied
pQCD-improved parton model incorporates intrinsic k_T. Nuclear multiscattering
and nuclear shadowing are considered in the Au nucleus. Theoretical results are
displayed for midrapidity and high pseudorapidity (eta), and compared to
preliminary PHENIX and BRAHMS data.Comment: Contributed to 17th International Conference on Ultra Relativistic
Nucleus-Nucleus Collisions (Quark Matter 2004), Oakland, California, 11-17
Jan 200
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
Jet Tomography in the Forward Direction at RHIC
Hadron production at high- displays a strong suppression pattern in a
wide rapidity region in heavy ion collisions at RHIC energies. This finding
indicates the presence of strong final state effects for both transversally and
longitudinally traveling partons, namely induced energy loss. We have developed
a perturbative QCD based model to describe hadron production in collision,
which can be combined with the Glauber -- Gribov model to describe hadron
production in heavy ion collisions. Investigating and collisions
at energy GeV at mid-rapidity, we find the opacity of the
strongly interacting hot matter to be proportional to the participant nucleon
number. Considering forward rapidities, the suppression pattern indicates the
formation of a longitudinally contracted dense deconfined zone in central heavy
ion collisions. We determine parameters for the initial geometry from the
existing data.Comment: 6 pages for Hot Quarks '06 Conferenc
CHEMICAL MODIFICATION OF CELLULOSE
Thermolytic degradation of cellulose is dependant on its initial DP, accessibility and on
the method and temperature of the treatment. A limiting DP could be detected in the
depolymerizing reaction. The deteriorating action of aggressive water could be demonstrated.
Quantitative correlation was elaborated concerning the role of accessibility in the reaction
between cellulose and reactive dyestuffs. The role of temperature was cleared up in the
ceIlulose-caustic soda interaction. New bleaching process was elaborated with the use of singlet
oxygen. Physical characteristics, amount of releasable formaldehyde and colouristic influence of
resin finishing of cotton could be optimized
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