Production of pions, kaons, (anti-)protons and φ mesons in Xe–Xe collisions at √sNN = 5.44 TeV

The first measurement of the production of pions, kaons, (anti-)protons and φ mesons at midrapidity in
Xe–Xe collisions at √sNN = 5.44 TeV is presented. Transverse momentum (pT) spectra and pT-integrated yields are
extracted in several centrality intervals bridging from p–Pb
to mid-central Pb–Pb collisions in terms of final-state multiplicity. The study of Xe–Xe and Pb–Pb collisions allows
systems at similar charged-particle multiplicities but with
different initial geometrical eccentricities to be investigated.
A detailed comparison of the spectral shapes in the two systems reveals an opposite behaviour for radial and elliptic flow.
In particular, this study shows that the radial flow does not
depend on the colliding system when compared at similar
charged-particle multiplicity. In terms of hadron chemistry,
the previously observed smooth evolution of particle ratios
with multiplicity from small to large collision systems is also
found to hold in Xe–Xe. In addition, our results confirm that
two remarkable features of particle production at LHC energies are also valid in the collision of medium-sized nuclei:
the lower proton-to-pion ratio with respect to the thermal
model expectations and the increase of the φ-to-pion ratio
with increasing final-state multiplicity.