Measurement of (anti)nuclei production in p-Pb collisions at $\sqrt{s_{\rm NN}} = 8.16$ TeV

Measurements of (anti)proton, (anti)deuteron, and (anti)$^3$He production in the rapidity range $-1<~y<~ 0$ as a function of the transverse momentum and event multiplicity in p-Pb collisions at a center-of-mass energy per nucleon-nucleon pair $\sqrt{s_{\rm NN}} = 8.16$ TeV are presented. The coalescence parameters $B_2$ and $B_3$, measured as a function of the transverse momentum per nucleon and of the mean charged-particle multiplicity density, confirm a smooth evolution from low to high multiplicity across different collision systems and energies. The ratios between (anti)deuteron and (anti)$^3$He yields and those of (anti)protons are also reported as a function of the mean charged-particle multiplicity density. A comparison with the predictions of the statistical hadronization and coalescence models for different collision systems and center-of-mass energies favors the coalescence description for the deuteron-to-proton yield ratio with respect to the canonical statistical model.

 

Submitted to: PLB
e-Print: arXiv:2212.04777 | PDF | inSPIRE
CERN-EP-2022-275
Figure group

Figure 1

Transverse momentum spectra of the average of protons and antiprotons (on the left) and of the average of deuterons and antideuterons (in the middle), in different multiplicity classes, and average of $^3\mathrm{He}$ and $^3\overline{\mathrm{He}}$ (on the right). The \pt distributions of deuterons and $^3$He are fitted using the Lévy--Tsallis function , while the \pt distributions of protons are fitted using the Blast-Wave fuction . Vertical bars and boxes represent statistical and systematic uncertainties, respectively.

Figure 2

Coalescence parameters $B_2$ (left panel) and $B_3$ (right panel) as a function of $p_{\mathrm T}$/$A$, measured for deuterons and $^3$He, respectively. Statistical uncertainties are represented as vertical lines whereas boxes represent the systematic ones.

Figure 3

$B_2$ as a function of the mean charged-particle multiplicity density for a fixed value of \mbox{$p_{\mathrm T}$/$A$ = 0.75 GeV/$c$}. The experimental results are compared to the coalescence calculations from Ref.  using two different parameterizations for the system size as a function of the mean charged-particle multiplicity density.

Figure 4

Ratio of deuteron (left panel) and of (anti)$^3$He (right panel) and proton production yields as a function of the charged-particle multiplicity in different collision systems and energies. Statistical uncertainties are represented as vertical lines, whereas boxes represent the systematic ones. The results are compared with the expectations of CSM and Coalescence models.