1,631 research outputs found
Elliptic Flow and Fixed p_T Suppression in a Final State Interaction Model
It has been shown that a final state interaction model, used to describe
J/psi suppression, can also describe the fixed p_T suppression of the pi^0 (and
charged pions) yield at all values of p_T, with a final state interaction
cross-section sigma close to one milibarn. We propose an extension of the model
to the pion motion in the transverse plane - which introduces a dependence of
the suppression on the azimuthal angle theta_R. Using the same value of sigma,
we obtain values of the elliptic flow v_2 close to the experimental ones, for
all values of p_T, including the soft p_T region.Comment: 21 pages, 6 figure
A model-independent analysis of the dependence of the anomalous J/psi suppression on the number of participant nucleons
A recently published experimental dependence of the J/psi to Drell-Yan ratio
on the measured, by a zero degree calorimeter, forward energy E_ZDC in Pb+Pb
collisions at the CERN SPS is analyzed. Using a model-independent approach it
is shown that the data are at variance with an earlier published experimental
dependence of the same quantity on the transverse energy of neutral hadrons
E_T. The discrepancy is related to a moderate centrality region: 100 < N_p <
200 (N_p is the number of participant nucleons) and is peculiar only to the
data obtained within the `minimum bias' analysis (using the `theoretical
Drell-Yan'). This could result from systematic experimental errors in the
minimum bias sample. A possible source of the errors is discussed.Comment: 10 pages, LaTeX, 3 PS-figures. V2: Misprints are correcte
Integrating Multimedia: Demonstrations of Student-Generated Multimedia Products Made within Regular Content-Driven Courses
Education doctoral students in five different courses demonstrated their understanding of key concepts though creating multimedia learning products. This demonstration looks at the use of student-generated multimedia products as a pedagogical strategy to encourage learners to think more deeply about academic content. This demonstration shares over 20 different multimedia products from these different courses. The products are encouraging since students demonstrated a deeper level of academic understanding and a higher level of student engagement
DTUJET--93 Sampling inelastic proton--proton and antiproton--proton collisions according to the two--component Dual Parton Model
A new version of a Monte Carlo Program for hadronic multi-particle production
is presented. It is based on the two-component Dual Parton Model which includes
the dual topological unitarization of soft and hard cross sections. The model
treats both soft (low ) and hard (minijet, large )
processes in a unified and consistent way. The unified description is important
at TeV-energies of hadron colliders, where the hard perturbative cross sections
of QCD become large and comparable to the total cross sections.Comment: 20 pages , PHYSZZX, SI-93-
Hard diffraction in hadron--hadron interactions and in photoproduction
Hard single diffractive processes are studied within the framework of the
triple--Pomeron approximation. Using a Pomeron structure function motivated by
Regge--theory we obtain parton distribution functions which do not obey
momentum sum rule. Based on Regge-- factorization cross sections for hard
diffraction are calculated. Furthermore, the model is applied to hard
diffractive particle production in photoproduction and in
interactions.Comment: 13 pages, Latex, 13 uuencoded figure
Damping of the HERA effect in DIS?
The drastic rise of the proton structure function F_2(x,Q^2) when the
Bj\"orken variable x decreases, seen at HERA for a large span of Q^2, negative
values for the 4-momentum transfer, may be damped when Q^2 increases beyond
several hundreds GeV^2. A new data analysis and a comparison with recent models
for the proton structure function is proposed to discuss this phenomenon in
terms of the derivative \partial ln F_2(x,Q^2)/\partial ln(1/x).Comment: 14 pages (LaTeX) including 7 figures, misprints are correcte
Transverse energy distributions and production in Pb+Pb collisions
We have analyzed the latest NA50 data on transverse energy distributions and
suppression in Pb+Pb collisions. The transverse energy distribution
was analysed in the geometric model of AA collisions. In the geometric model,
fluctuations in the number of NN collisions at fixed impact parameter are taken
into account. Analysis suggests that in Pb+Pb collisions, individual NN
collisions produces less , than in other AA collisions. The nucleons are
more transparent in Pb+Pb collisions. The transverse energy dependence of the
suppression was obtained following the model of Blaizot et al, where
charmonium suppression is assumed to be 100% effective above a threshold
density. With fluctuations in number of NN collisions taken into account, good
fit to the data is obtained, with a single parameter, the threshold density.Comment: Revised version with better E_T fit. 4 pages, 2 figure
Calculation Of Secondary Particles In Atmosphere And Hadronic Interactions
Calculation of secondary particles produced by the interaction of cosmic rays
with the nuclei of Earth's atmosphere pose important requirements to particle
production models. Here we summarize the important features of hadronic
simulations, stressing the importance of the so called ``microscopic''
approach, making explicit reference to the case of the FLUKA code. Some
benchmarks are also presented.Comment: 10 pages, 4 figures. Extended version of report given at the IInd
Workshop on Matter and anti-Matter, Trento, Oct. 200
Charmonium Suppression in Lead-Lead Collisions: Is There a Break in the Cross-Section?
In the framework of a model based on nuclear absorption plus comover
interaction, we compute the distribution of the in
collisions at SPS and compare it with available NA50 data. Our analysis
suggests that the existence of new physics (deconfinement phase transition) in
the region E_{T} \lsim 100 GeV is unlikely and that signals of new physics
should rather be searched in the region E_T \gsim 100 GeV. The
dependence of the transverse momentum has been computed. At large
it turns out to be much flatter in the comover approach than in a phase
transition framework. Estimates of the suppression at RHIC and LHC
energies are also given.Comment: 31 pages, LaTeX, 9 postscript figures included using epsfig;
references updated and comments added; final version to appear in Phys. Rev.
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