New feature of low $$p_{T}$$ p T charm quark hadronization in pp collisions at $$\sqrt{s}=7$$

Abstract

Treating the light-flavor constituent quarks and antiquarks whose momentum information is extracted from the data of soft light-flavor hadrons in pp collisions at √ s = 7 TeV as the underlying source of chromatically neutralizing the charm quarks of low transverse momenta ( p T ), we show that the experimental data of p T spectra of single-charm hadronsTeV can be well understood by the equal-velocity combination of perturbatively created charm quarks and those light-flavor constituent quarks and antiquarks. This suggests a possible new scenario of low p T charm quark hadronization, in contrast to the traditional fragmentation mechanism, in pp collisions at LHC energies. This is also another support for the exhibition of the soft constituent quark degrees of freedom for the small parton system created in pp collisions at LHC energies.

Elliptic flow of hadrons in equal-velocity quark combination mechanism in relativistic heavy-ion collisions

“…This property is the direct consequence of the equal-velocity combination (EVC) of constituent quarks and antiquarks at hadronization. We further demonstrated that EVC can self-consistently explain the data of p T spectra for different identified hadrons in high multiplicity pp and p-Pb collisions at LHC energies [20,[22][23][24] and in heavy-ion collisions in a wide collision energy range [25]. Taking advantage of rich data for hadronic v 2 in heavy-ion collisions, in particular, at RHIC BES energies [6][7][8]26,27], it is interesting to further study whether this EVC mechanism works for v 2 of hadrons or not.…”

“…We note that this extraction is only valid in the low p T range where the combination dominates D meson production. In previous studies [23,24], we found that experimental data for p T spectra of single-charmed hadrons in the range p T 8 GeV/c in pp and pPb collisions at LHC energies are well described by the EVC model. Therefore, experimental data of v 2 for D mesons with p T 8 GeV/c can be used to extract v 2 of charm quarks with p T 6 GeV/c in EVC model.…”

“…The EVC can be applied not only to light-flavor quarks but also to heavy-flavor quarks at hadronization [33]. In [23,24,34], we show the EVC of charm quarks and soft light-flavor quarks provides good description for p T spectra of singlecharm hadrons in high energy collisions. Applying EVC to elliptic flows of D 0,± mesons, we obtain…”

Charmed-baryon production and hadronization studies with ALICE

“…Several mechanisms have been proposed to explain this enhancement. These mechanisms include colour reconnection beyond leading colour approximation [3], coalescence [4], and feed-down from several higher mass charm states as suggested by He and Rapp [5]. In this contribution, we report on measurements made of the charmed baryons…”

Charm baryon production and fragmentation fractions in pp collisions with ALICE

“…The model calculation from PYTHIA8 Monash [8] largely underestimates the measurement, the statistical hadronisation model (SHM) with excited charm baryon states predicted by the relativistic quark model (RQM) [9] can describe the measurement within uncertainties. The model calculations of Catania [10] and quark (re-)combination mechanism (QCM) [11] both including the coalescence process, also can describe the measurement. In general, PYTHIA8 implemented colour reconnection beyond the leading-colour approximation (CR-BLC) [12] better describes the Λ + c /D 0 ratio and Σ 0,++ c /D 0 ratio, which do not contain the strange quarks.…”