Viktor Begun

Bose-Einstein condensation of pions in high multiplicity events

Abstract We present microcanonical ensemble calculations of particle number fluctuations in the ideal pion gas approaching Bose–Einstein condensation. At high collision energy, in the samples of events with a fixed number of all pions, N π , one may observe a prominent signal. When N π increases the scaled variances for particle number fluctuations of both neutral and charged pions increase dramatically in the vicinity of the Bose–Einstein condensation line. As an example, the estimates are presented for p + p collisions at the beam energy of 70 GeV.

Transverse-momentum spectra of strange particles produced in Pb+Pb collisions at

We analyze the transverse-momentum spectra of strange hadrons produced in Pb+Pb collisions at the collision energy p sNN = 2:76 TeV. Our approach combines the concept of chemical non-equilibrium with the single-freeze-out scenario. The two ideas are realized in the framework of the Cracow model, whose thermodynamic parameters have been established in earlier studies of the ratios of hadron multiplicities. The geometric parameters of the model are obtained from the t to the spectra of pions

\sqrt{s_{\rm NN}}=2.76

The by now well-established scalar-isoscalar resonance

TeV in the chemical non-equilibrium model

f_{0}(500)

Cancellation of the

(the

\sigma

\sigma

meson in thermal models

meson) seems potentially relevant in the evaluation of thermodynamic quantities of a hadronic gas, since its mass is low. However, we recall that its contribution to isospin-averaged observables is, to a surprising accuracy, canceled by the repulsion from the pion-pion scalar-isotensor channel. As a result, in practice one should not incorporate

Explanation of hadron transverse-momentum spectra in heavy-ion collisions at

f_0(500)

\sqrt s_{NN} =

in standard hadronic resonance-gas models for studies of isospin averaged quantities. In our analysis we use the formalism of the virial expansion, which allows one to calculate the thermal properties of an interacting hadron gas in terms of derivatives of the scattering phase shifts, hence in a model-independent way directly from experimentally accessible quantities. A similar cancellation mechanism occurs for the scalar kaonic interactions between the

2.76 TeV within chemical non-equilibrium statistical hadronization model

I=1/2