317 research outputs found
A Decision Support System for Assessing Alternative Projects for the Design of a New Road Network
Resonances and fluctuations at SPS and RHIC
We perform an analysis of preliminary data on hadron yields and fluctuations
within the Statistical hadronization ansatz. We describe the theoretical
disagreements between different statistical models currently on the market, and
show how the simultaneous analysis of yields and fluctuations can be used to
determine if one of them can be connected to underlying physics. We perform
such an analysis on preliminary RHIC and SPS A-A data that includes particle
yields, ratios and event by event fluctuations. We show that the equilibrium
statistical model can not describe the fluctuation measured at RHIC and
SPS, unless an unrealistically small volume is assumed. Such small volume then
makes it impossible to describe the total particle multiplicity. The
non-equilibrium model,on the other hand, describes both the fluctuation
and yields acceptably due to the extra boost to the fluctuation provided
by the high pion chemical potential. We show, however, that both models
significantly over-estimate the fluctuation measured at the SPS, and
speculate for the reason behind this.Comment: Presented at Hot Quarks, 2006 In press, European Physical Journal
The THEMA tool to support heritage-based development strategies for marginal areas: Evidence from an Italian inner area in Campania Region
The ongoing forced reflection on the leading urbanization models’ crisis has led to greater attention to marginal areas. In Italy, the scientific and media debate has focused on inner areas that, since 2014, have represented the target of an innovative national cohesion policy aimed at tackling their shrinking dynamics: the National Strategy for Inner Areas (SNAI). Indeed, Italian inner areas are endowed with extraordinary natural capital and settlement models far from urban density. Thus, they seem to respond perfectly to the new raised living needs. However, leaving aside the optimistic rhetoric, strong political and administrative choices are necessary to trigger a ‘return process’ based on this broader attention toward inner areas, thus countering humankind’s natural tendency to concentrate on urban realities. In this light, the paper proposes a tool to support SNAI in designing and implementing heritage-based local development strategies to address inner areas’ real needs. After a critical reading of the new challenges for planning posed by the pandemic and SNAI’s role within them, the contribution moves to frame the THEMA (Tool for Heritage-based Enhancement of Marginal Areas) tool, focusing on specificities of the inner areas as cultural heritage. Finally, the tool’s application to a case study, an inner area in Campania Region, allows to outline and discuss its possible benefits for SNAI implementation and its limits
Scaling of in heavy ion collisions
We interpret the scaling of the corrected elliptic flow parameter w.r.t. the
corrected multiplicity, observed to hold in heavy ion collisions for a wide
variety of energies and system sizes. We use dimensional analysis and
power-counting arguments to place constraints on the changes of initial
conditions in systems with different center of mass energy .
Specifically, we show that a large class of changes in the (initial) equation
of state, mean free path, and longitudinal geometry over the observed
are likely to spoil the scaling in observed experimentally. We
therefore argue that the system produced at most Super Proton Synchrotron (SPS)
and Relativistic Heavy Ion Collider (RHIC) energies is fundamentally the same
as far as the soft and approximately thermalized degrees of freedom are
considered. The ``sQGP'' (Strongly interacting Quark-Gluon Plasma) phase, if it
is there, is therefore not exclusive to RHIC. We suggest, as a goal for further
low-energy heavy ion experiments, to search for a ``transition''
where the observed scaling breaks.Comment: Accepted for publication by Phys. Rev. C Based on presentation in
mini-symposium on QGP collective properties, Frankfurt. Discussion expanded,
results adde
A Decision Support System for Assessing Alternative Projects for the Design of a New Road Network: Methodology and Application to a Case Study
Resonances and fluctuations of strange particle in 200 GeV Au-Au collisions
We perform an analysis of preliminary data on strange particles yields and
fluctuations within the Statistical hadronization model. We begin by describing
the theoretical disagreements between different statistical models currently on
the market. We then show how the simultaneous analysis of yields and
fluctuations can be used to differentiate between the different models, and
determine if one of them can be connected to underlying physics. We perform a
study on a RHIC 200 GeV data sample that includes stable particles, resonances,
and the event-by-event fluctuation of the ratio. We show that the
equilibrium statistical model can not describe the fluctuation, unless an
unrealistically small volume is assumed. Such small volume then makes it
impossible to describe the total particle multiplicity. The non-equilibrium
model,on the other hand, describes both the fluctuation and yields
acceptably due to the extra boost to the fluctuation provided by the high
pion chemical potential. and abundance is described
within error bars, but the is under-predicted to 1.5 standard
deviations. We suggest further measurements that have the potential to test the
non-equilibrium model, as well as gauge the effect of re-interactions between
hadronization and freeze-out.Comment: References added, equations corrected. As accepted for publication by
Journal of Physics
Fluctuations of particle ratios as a freeze-out probe
We explain how event-by-event fluctuations of particle ratios can constrain
and falsify the statistical model of particle production in heavy ion
collisions, using fluctuations as an example. We define an observable
capable of determining which statistical model, if any, governs freeze-out in
ultrarelativistic heavy ion collisions. We calculate this observable for
fluctuations, and show that it should be the same for RHIC and LHC
energies, as well as independent of centrality, if the Grand-Canonical
statistical model is an appropriate description and chemical equilibrium
applies. We describe what happens in case of deviations from this scenario,
such as light quark chemical non-equilibrium, strange quark over-saturation and
local conservation (canonical ensemble) for strange quarks. We also introduce a
similar observable capable, together with the published measurement, of
ascertaining if an interacting hadron gas phase governs the system between
thermal and chemical freeze-out, and of ascertaining its duration and impact on
hadronic chemistryComment: Proceedings for talk given at Strangeness 2007, Levoca, Slovaki
Strange Hadron Resonances and QGP Freeze-out
We describe how the abundance and distribution of hyperon resonances can be
used to probe freeze-out conditions. We demonstrate that resonance yields allow
us to measure the time scales of chemical and thermal freeze-outs. This should
permit a direct differentiation between the explosive sudden, and staged
adiabatic freeze-out scenarios.Comment: 8 pages including 4 figures, in Proceedings of Strange Quark Matter
2001, Frankfurt, submitted to J. Phys. G version 2: refernces
corrected/added, numercial corrections in figures 2,3,
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