Phys. Rev. C 94, 044906 (2016) Production of $d$, $t$, and $^3$He nuclei in central Pb+Pb interactions was
studied at five collision energies ($\sqrt{s_{NN}}=$ 6.3, 7.6, 8.8, 12.3, and
17.3 GeV) with ...the NA49 detector at the CERN SPS. Transverse momentum spectra,
rapidity distributions, and particle ratios were measured. Yields are compared
to predictions of statistical models. Phase-space distributions of light nuclei
are discussed and compared to those of protons in the context of a coalescence
approach. The coalescence parameters $B_2$ and $B_3$, as well as coalescence
radii for $d$ and $^3$He were determined as a function of transverse mass at
all energies.
A novel approach, the identity method, was used for particle identification and the study of fluctuations of particle yield ratios in Pb+Pb collisions at the CERN Super Proton Synchrotron (SPS). This ...procedure allows to unfold the moments of the unknown multiplicity distributions of protons (p), kaons (K), pions (\(\pi\)) and electrons (e). Using these moments the excitation function of the fluctuation measure \(\nu_{\text{\text{dyn}}}\)A,B was measured, with A and B denoting different particle types. The obtained energy dependence of \(\nu_{\text{dyn}}\) agrees with previously published NA49 results on the related measure \(\sigma_{\text{dyn}}\). Moreover, \(\nu_{\text{dyn}}\) was found to depend on the phase space coverage for K,p and K,\(\pi\) pairs. This feature most likely explains the reported differences between measurements of NA49 and those of STAR in central Au+Au collisions.
We look for fluctuations expected for the QCD critical point using an
intermittency analysis in the transverse momentum phase space of protons
produced around midrapidity in the 12.5\% most central ...C+C, Si+Si and Pb+Pb
collisions at the maximum SPS energy of 158$A$~GeV. We find evidence of
power-law fluctuations for the Si+Si data. The fitted power-law exponent
$\phi_{2} = 0.96^{+0.38}_{-0.25}\text{ (stat.)}$ $\pm 0.16\text{ (syst.)}$ is
consistent with the va\-lue expected for critical fluctuations. Power-law
fluctuations had previously also been observed in low-mass $\pi^+ \pi^-$ pairs
in the same Si+Si collisions.
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