Abstract (data abstract)

In this letter, measurements of (anti)alpha production in central (0-10%) Pb--Pb collisions at a center-of-mass energy per nucleon--nucleon pair of $\sqrt{s_{\mathrm{NN}}}$ = 5.02 TeV are presented, including the first measurement of an antialpha transverse-momentum spectrum. Owing to its large mass, (anti)alpha production yields and transverse-momentum spectra are of particular interest because they provide a stringent test of particle production models. The averaged antialpha and alpha spectrum is included into a common blast-wave fit with lighter particles, indicating that the (anti)alpha also participates in the collective expansion of the medium created in the collision. A blast-wave fit including only protons, (anti)alpha, and other light nuclei results in a similar flow velocity as the fit that includes all particles. A similar flow velocity, but a significantly larger kinetic freeze-out temperature is obtained when only protons and light nuclei are included in the fit. The coalescence parameter $B_4$ is well described by calculations from a statistical hadronization model but significantly underestimated by calculations assuming nucleus formation via coalescence of nucleons. Similarly, the (anti)alpha-to-proton ratio is well described by the statistical hadronization model. On the other hand, coalescence calculations including approaches with different implementations of the (anti)alpha substructure tend to underestimate the data.

Antialpha spectrum

Data from Figure 2.

10.17182/hepdata.153848.v1/t1

Antialpha spectrum in 0-10% V0M centrality class
Alpha spectrum

Data from Figure 2.

10.17182/hepdata.153848.v1/t2

Alpha spectrum in 0-10% V0M centrality class
Average alpha+antialpha spectrum

Data from Figure 3.

10.17182/hepdata.153848.v1/t3

Average alpha and antialpha spectrum in 0-10% V0M centrality class
Coalescence B_4 from average alpha+antialpha

Data from Figure 4.

10.17182/hepdata.153848.v1/t4

Coalescence parameter $B_4$ from average alpha and antialpha as a function of $p_{\mathrm{T}}$ in 0-10% V0M centrality class
Average alpha+antialpha over proton ratio

Data from Figure 5.

10.17182/hepdata.153848.v1/t5

Average alpha and antialpha over proton ratio in Pb-Pb collisions as a function of the charged particle multiplicity density at...
Yield antialpha

Data from Table 2.

10.17182/hepdata.153848.v1/t6

pT-integrated yield of antialpha in Pb-Pb collisions in 0-10% V0M centrality class
Yield alpha

Data from Table 2.

10.17182/hepdata.153848.v1/t7

pT-integrated yield of alpha in Pb-Pb collisions in 0-10% V0M centrality class
Yield average alpha+antialpha

Data from Table 2.

10.17182/hepdata.153848.v1/t8

pT-integrated yield of average alpha and antialpha in Pb-Pb collisions in 0-10% V0M centrality class

Antialpha spectrum

Alpha spectrum

Average alpha+antialpha spectrum

Coalescence B_4 from average alpha+antialpha

Average alpha+antialpha over proton ratio

Yield antialpha

Yield alpha

Yield average alpha+antialpha

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