Transverse momentum spectra and correlations in the blast wave model with resonances

This work provides a review of theories of properties of high energy density matter originating in heavy-ion high energy collisions (GeV/nucleus).


This work provides a review of theories of properties of high energy density matter originating in heavy-ion high energy collisions (GeV/nucleus). The work contains an introduction to the extreme state of matter called quark-gluon plasma, quantum statistical mechanics, and theory of longitudinally boost-invariantly expanding fireball of a hot matter.

Particular intention is given to the blast-wave model with resonances, whose basic assumptions are longitudinally boost-invariant expansion, transverse expansion, and the existence of a particular hypersurface in space-time, on which hadronic matter abruptly decouples from fireball.

In the final part two most important parameters of the blast-wave model are extracted from fits to the transverse momentum spectra obtained from STAR experiment, using a modification of the program DRAGON [B. Tomasik, Comp.Phys.Commun. 180 (2009) 1642-1653].


With the help of software modification of some outputs of the DRAGON program, I have fitted the two most important parameters of the Blastwave model with resonances to the normalized (see sub-chapter 4.3.1) spectra in transverse momentum from the STAR experiment : E [GeV] ηf Tf o [GeV] χ^2 min(E) 62.4 0.8 0.08 2.66 130 0.8 0.08 2.35 200 0.9 0.08 0.81 Table 4.2: Values of parameter ηf, Tf o [GeV] for found minima of function χ^2(ηf, Tf o) (see sub-chapter 4.3.2) and for different energies see also tables in Appendix A.3.

It is interesting that even though the spectra for the fitted values ​​correspond quite well (see graphs in sub-chapter 4.3.2). However, the freeze-out temperature Tf o values are approximately half compared to previous estimates. There could be several explanations:

  • Even though the chosen parameters are significant, it is necessary to adjust the others as well.
  • The region in transverse momentum I analyzed is too narrow.
  • It is necessary to adjust the chemical composition parameter for energy 62.4 [GeV].
  • The choice of the freeze-out super-surface of the Blastwave model is not suitable.

A possible continuation of this work would be to add the results of the influence of symmetrization - HBT interferometry as additional data (see sub-chapter 3.6).


Vaclav Kosar

Key words

ultrarelativistic nuclear collisions, logitudinally boost-invariat expanding fireball, Blastwave model, transverse momentum spectra, DRAGON

Created on 05 Sep 2010.
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