Particle Spectra in Statistical Models with Energy and Momentum Conservation

TL;DR

This paper investigates how energy and momentum conservation laws affect single particle momentum spectra in micro-canonical statistical models, revealing deviations from grand canonical predictions relevant for high-energy nuclear collision analyses.

Contribution

It provides a detailed comparison of particle spectra under different conservation constraints, highlighting their impact at LHC energies and small system sizes.

Findings

Conservation laws cause measurable deviations in spectra at transverse momenta around 3 GeV/c.

Effects are significant for small systems like p+p collisions at LHC energies.

Results aid in interpreting high-energy nuclear collision data.

Abstract

Single particle momentum spectra are calculated within three micro-canonical statistical ensembles, namely, with conserved system energy, system momentum, as well as system energy and momentum. Deviations from the exponential spectrum of the grand canonical ensemble are quantified and discussed. For mean particle multiplicity and temperature, typical for p+p interactions at the LHC energies, the effect of the conservation laws extends to transverse momenta as low as about 3 GeV/c. The results may help to interpret spectra measured in nuclear collisions at high energies, in particular, their system size dependence.