### Refine

#### Year of publication

- 2000 (3) (remove)

#### Keywords

- Kollision (1)
- Nukleon (1)
- Pion Gas (1)
- collision (1)
- heiße Pion Materie (1)
- hot pion matter (1)
- nucleon (1)
- open charm yield (1)
- open charm yield (1)
- pion gas (1)

- Second cluster integral and excluded volume effects for the pion gas (2000)
- The quantum mechanical formula for Mayer s second cluster integral for the gas of relativistic particles with hard-core interaction is derived. The proper pion volume calculated with quantum mechanical formula is found to be an order of magnitude larger than its classical evaluation. The second cluster integral for the pion gas is calculated in quantum mechanical approach with account for both attractive and hard-core repulsive interactions. It is shown that, in the second cluster approximation, the repulsive -interactions as well as the finite width of resonances give important but almost canceling contributions. In contrast, an appreciable deviation from the ideal gas of pions and pion resonances is observed beyond the second clus- ter approximation in the framework of the Van der Waals excluded-volume model.

- Open charm enhancement in Pb + Pb collisions at SPS (2000)
- 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.

- Phase transition in hot pion matter (2000)
- The equation of state for the pion gas is analyzed within the third virial approximation. The second virial coeffcient is found from the pi pi -scattering data, while the third one is considered as a free parameter. The proposed model leads to a first-order phase transition from the pion gas to a more dense phase at the temperature Tpt < 136 MeV. Due to relatively low temperature this phase transition cannot be related to the deconfinement. This suggests that a new phase of hadron matter hot pion liquid may exist.