Transverse momentum and multiplicity dependence of ${\Lambda }_c^{+}/D^0$ ratio in $pp$ collisions at $\sqrt{s}=13$ TeV

Abstract

We apply an equal-velocity quark combination model to study the ${\Lambda }_c^{+}/D^0$ ratio in the range $p_T\lesssim 10$ GeV/c in $pp$ collisions at $\sqrt{s}=13$ TeV. We decompose the ratio into four parts which are related to quark numbers, light-flavor quark $p_T$ spectrum, charm quark $p_T$ spectrum, momentum correlation between light and charm quarks, respectively. Their influence on ${\Lambda }_c^{+}/D^0$ ratio are individually studied. The curvature property of light-flavor quark $p_T$ spectrum is found to be the main reason of the non-monotonic $p_T$ dependence of ${\Lambda }_c^{+}/D^0$ ratio exhibited in high multiplicity events. Moreover, the multiplicity dependence of ${\Lambda }_c^{+}/D^0$ ratio as the function of $p_T$ is mainly because of the multiplicity dependence of light-flavor quark $p_T$ spectrum. Using the light-flavor quark $p_T$ spectrum obtained from experimental data of light-flavor hadrons and charm quark $p_T$ spectrum obtained from FONLL and/or PYTHIA calculations, the $p_T$ dependence of experimental data of ${\Lambda }_c^{+}/D^0$ ratio in high multiplicity events and that in low multiplicity events in $pp$ collisions at $\sqrt{s}=13$ TeV are reasonably understood.

Comments: 13 pages, 5 figures