Abstract
If QGP-like medium is created in $p$-Pb collisions at extremely high collision energies, charm quarks that move in the medium can hadronize by capturing the co-moving light quark(s) or anti-quark(s) to form the charm hadrons. Using light quark $p_{T}$ spectra extracted from the experimental data of light-flavor hadrons and a charm quark $p_{T}$ spectrum that is consistent with perturbative QCD calculations, the central-rapidity data of $p_{T}$ spectra and the spectrum ratios for $D$ mesons in the low $p_{T}$ range ($p_{T}\lesssim7$ GeV/$c$) in minimum-bias $p$-Pb collisions at $\sqrt{s_{NN}}=5.02$ TeV are well described by quark combination mechanism in equal-velocity combination approximation. The $\Lambda_{c}^{+}/D^{0}$ ratio in quark combination mechanism exhibits the typical increase-peak-decrease behavior as the function of $p_{T}$, and the shape of the ratio for $p_{T}\gtrsim3$ GeV/$c$ is in agreement with the data of ALICE collaboration in central rapidity region $-0.96<y<0.04$ and the preliminary data of LHCb collaboration in forward rapidity region $1.5<y<4.0$. The global production of single-charm baryons is quantified using the data and the possible enhancement (relative to light flavor baryons) is discussed. The $p_{T}$ spectra of $\Xi_{c}^{0}$, $\Omega_{c}^{0}$ in minimum-bias events and those of single-charm hadrons in high-multiplicity event classes are predicted, which serves as the further test of the possible change of the hadronization characteristic for low $p_{T}$ charm quarks in the small system created in $p$-Pb collisions at LHC energies.
Highlights
Quark-gluon plasma (QGP) in which quarks and gluons are deconfined is a new state of the matter of QCD [1], which is significantly different from the normal nuclear matter
/D0 ratio in quark combination mechanism exhibits the typical increasepeak-decrease behavior as the function of pT, and the shape of the ratio for pT 3 GeV/c is in agreement with the data of the ALICE Collaboration in central rapidity region −0.96 < y < 0.04 and the preliminary data of the
We introduced a working model in the framework of a quark combination mechanism to formulate the yields and momentum distributions of singlecharm hadrons formed by the combination of charm quarks and light-flavorquarks in an equal-velocity combination approximation
Summary
Quark-gluon plasma (QGP) in which quarks and gluons are deconfined is a new state of the matter of QCD [1], which is significantly different from the normal nuclear matter. Recent ALICE, CMS, and ATLAS experiments find with great surprise that the production of hadrons in high-multiplicity p-Pb and pp collisions at the Large Hadron Collider (LHC) exhibits a series of remarkable similarities with that in heavy-ion collisions where QGP is created These striking observations include long-range angular correlations [2,3,4,5] and collectivity [6,7,8], enhanced strangeness [9,10], and enhanced baryon-to-meson ratio at low transverse momentum (pT ) [11,12], etc. TeV exhibit an interesting constituent quark number scaling Such scaling behavior indicates the change of hadronization characteristic in low-pT range from the traditional string and cluster fragmentation to the quark (re)combination mechanism in light (up, down, strange) sector and is a possible signature for the formation of small dense parton medium in collisions.
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