Measurement of (anti)alpha production in central Pb-Pb collisions at $\sqrt{s_{\rm NN}}$ = 5.02 TeV

The ALICE collaboration
Phys.Lett.B 858 (2024) 138943, 2024.

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

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