Excluded-volume effects for a hadron gas in Yang-Mills theory

Abstract

When the multiplicities of particles produced in heavy-ion collisions are fitted to the hadron-resonancegas model, excluded-volume effects play a significant role. In this work, we study the impact of such effects on the equation of state of pure Yang-Mills theory at low temperatures, comparing the predictions of the statistical model with lattice results. In particular, we present a detailed analysis of the SU(2) and SU(3) Yang-Mills theories: we find that, for both of them, the best fits to the equilibrium thermodynamic quantities are obtained when one assumes that the volume of different glueball states is inversely proportional to their mass. The implications of these findings for QCD are discussed.

Balance of attractive and repulsive hadronic interactions: The influence of hadronic spectrum and excluded-volume effects on lattice thermodynamics, and consequences for experiments

“…In this case the best χ 2 is given by the combined use of QM list and an eigenvolume which increases with hadronic mass. This is similar to what was found in [14] for the pure gauge. However the different flavours and quantum numbers present in QCD allow for a deeper study.…”

“…Keeping all of this in mind, we perform a systematic study on differences between light and strange sectors, allowing resonances to have very different behaviours with respect to ground states; namely we consider different combinations of the following schemes: fixed radii (r ) for all particles, radii directly (b) and inversely (inv ) proportional to particle mass. For the sake of simplicity, we will parameterise different EV schemes by means of ground state radii (π, K, p and Λ) [14], which will be specified time by time. We use data from lattice simulations, extrapolated to the continuum with physical values for the quark masses, for the following observables: pressure, interaction measure [42], χ ud 11 , χ us 11 [1], χ ss [40].…”

“…In the present paper we parameterise hadronic repulsive interactions by means of EV-HRG employing different particle lists and interaction schemes, thus extracting from lattice thermodynamics information on the effective sizes of hadrons, or namely their effective interactions. This approach has already been successfully applied for analysing lattice simulations for SU2 and SU3 gauge theories [14], with different schemes and accounting for higher mass states by means of an Hagedorn spectrum. Results showed a systematic presence of EV effects, with consistency between glueball masses in the two theories.…”

Improved thermodynamics of SU(2) gauge theory

“…Comparison of the trace anomaly in the confined phase, measured in this work, with data taken from Ref [52]…”

“…Moreover, we can compare our results, in the confined phase, with those published in Refs. [51,52] where they simulate SU(2) pure gauge theory but, also in this case, using the standard Wilson action at fixed volume. However, they simulate different values of N τ , ranging from 5 to 10.…”