2,550 research outputs found
Precision compliance techniques for slow crack growth measurements
A method is presented for using simple electronic components to obtain the high sensitivity needed to measure very slow crack growth rates. The technique presented can reduce the experimental time considerably and also yield a greater amount of data more accurately than optical techniques for measuring crack growth rates
Thermalization through Hagedorn states - the importance of multiparticle collisions
Quick chemical equilibration times of hadrons within a hadron gas are
explained dynamically using Hagedorn states, which drive particles into
equilibrium close to the critical temperature. Within this scheme master
equations are employed for the chemical equilibration of various hadronic
particles like (strange) baryon and antibaryons. A comparison of the Hagedorn
model to recent lattice results is made and it is found that for both Tc =176
MeV and Tc=196 MeV, the hadrons can reach chemical equilibrium almost
immediately, well before the chemical freeze-out temperatures found in thermal
fits for a hadron gas without Hagedorn states.Comment: 8 pages, 3 figures, talk presented at the International Conference on
Strangeness in Quark Matter, Buzios, Rio de Janeiro, Brazil, Sept. 27 - Oct.
2, 200
Chemical Equilibration and Transport Properties of Hadronic Matter near
We discuss how the inclusion of Hagedorn states near leads to short
chemical equilibration times of proton anti-proton pairs, pairs, and
pairs, which indicates that hadrons do not need to be
"born" into chemical equilibrium in ultrarelativistic heavy ion collisions. We
show that the hadron ratios computed within our model match the experimental
results at RHIC very well. Furthermore, estimates for near
computed within our resonance gas model are comparable to the string theory
viscosity bound . Our model provides a good description of the
recent lattice results for the trace anomaly close to MeV.Comment: 4 pages, 3 figures, to appear in the conference proceedings for Quark
Matter 2009, March 30 - April 4, Knoxville, Tennesse
Particle Ratios as a Probe of the QCD Critical Temperature
We show how the measured particle ratios can be used to provide non-trivial
information about the critical temperature of the QCD phase transition. This is
obtained by including the effects of highly massive Hagedorn resonances on
statistical models, which are used to describe hadronic yields. The inclusion
of Hagedorn states creates a dependence of the thermal fits on the Hagedorn
temperature, , which is assumed to be equal to , and leads to an
overall improvement of thermal fits. We find that for Au+Au collisions at RHIC
at GeV the best square fit measure, , occurs at
MeV and produces a chemical freeze-out temperature of 172.6 MeV
and a baryon chemical potential of 39.7 MeV.Comment: 6 pages, 4 figure
Particle Ratios and the QCD Critical Temperature
We show how the measured particle ratios at RHIC can be used to provide
non-trivial information about the critical temperature of the QCD phase
transition. This is obtained by including the effects of highly massive
Hagedorn resonances on statistical models, which are used to describe hadronic
yields. Hagedorn states are relevant close to and have been shown to
decrease to the KSS limit and allow for quick chemical equilibrium
times in dynamical calculations of hadrons. The inclusion of Hagedorn states
creates a dependence of the thermal fits on the Hagedorn temperature, ,
which is assumed to be equal to , and leads to an overall improvement of
thermal fits. We find that for Au+Au collisions at RHIC at
GeV the best square fit measure, , occurs at MeV and
produces a chemical freeze-out temperature of 170.4 MeV and a baryon chemical
potential of 27.8 MeV.Comment: 6 pages, 2 figures, talk presented at the International Conference on
Strangeness in Quark Matter, Buzios, Rio de Janeiro, Brazil, Sept. 27 - oct.
2, 200
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