2019/02/28 by Min He, Ralf Rapp · 1 citation
Physics and Astronomy · #nucl-th #hep-ex #hep-ph #nucl-ex
paper · pdf · doi:10.1016/j.physletb.2019.06.004
7 pages, 3 figures; Ref.[17] updated
arxiv created 2019/02/28 · arxiv updated 2019/07/24
Recent measurements of charm-baryon production in proton-proton collisions at the LHC have found a surprisingly large yield relative to those of D-mesons. We propose that this observation can be explained by the statistical hadronization model (SHM), by employing a largely augmented set of charm-baryon states beyond the current listings of the particle data group. We estimate the additional states using guidance from the relativistic quark model and from lattice QCD. Using charm- and strange-quark fugacity factors to account for the well-known suppression of heavy flavor in elementary collisions, we compute the yields and spectra of D, Ds and Λc hadrons in proton-proton collisions at √(s)=5 TeV. Our main finding is that the enhanced feeddown from excited charm baryons can account for the Λc/D0 ratio measured by ALICE at midrapidity, with some caveat for the forward-rapidity LHCb data. Furthermore, assuming independent fragmentation of charm quarks but with the hadronic ratios fixed by the SHM, the measured transverse-momentum (pT) spectra of D-mesons and Λc can also be described; in particular, the low-pT enhancement in the observed Λc/D0 ratio is attributed to the enhanced feeddown from "missing" charm-baryon states. We comment on the implications of these findings for measurements of Ds and Λc in heavy-ion collisions.