Phys Rev Lett. 2023 Jul 7;131(1):012301. doi: 10.1103/PhysRevLett.131.012301.
ABSTRACT
The hadrochemistry of bottom quarks (b) produced in hadronic collisions encodes valuable information on the mechanism of color neutralization in these reactions. Since the b-quark mass is much larger than the typical hadronic scale of ∼1 GeV, bb[over ¯] pair production is expected to be well separated from subsequent hadronization processes. A significantly larger fraction of b baryons has been observed in proton-proton (pp) and proton-antiproton (pp[over ¯]) reactions relative to e^{+}e^{-} collisions, challenging theoretical descriptions. We address this problem by employing a statistical hadronization approach with an augmented set of b-hadron states beyond currently measured ones, guided by the relativistic quark model and lattice-QCD computations. Assuming relative chemical equilibrium between different b-hadron yields, thermal densities are used as fragmentation weights of b quarks into various hadron species. With quark model estimates of the decay patterns of excited states, the fragmentation fractions of weakly decaying b hadrons are computed and found to agree with measurements in pp[over ¯] collisions at the Tevatron. By combining transverse-momentum (p_{T}) distributions of b quarks from perturbative QCD with thermal weights and independent fragmentation toward high p_{T}, a fair description of the p_{T}-dependent B[over ¯]_{s}^{0}/B^{-} and Λ_{b}^{0}/B^{-} ratios measured in pp collisions at the LHC is obtained. The observed enhancement of Λ_{b}^{0} production is attributed to the feeddown from thus far unobserved excited b baryons. Finally, we implement the hadrochemistry into a strongly coupled transport approach for b quarks in heavy-ion collisions, utilizing previously determined b-quark transport coefficients in the quark-gluon plasma, to highlight the modifications of hadrochemistry and collective behavior of b hadrons in Pb-Pb collisions at the LHC.
PMID:37478427 | DOI:10.1103/PhysRevLett.131.012301
