Measurement of prompt D-meson production in p-Pb collisions at $\sqrt{s_{\rm NN}}$ = 5.02 TeV

TL;DR

This paper reports the measurement of prompt D-meson production cross sections and RpPb in p-Pb collisions at √sNN=5.02 TeV with the ALICE detector. D0, D+, D*+, and Ds+ are reconstructed via hadronic decays in -0.96<y_cm<0.04, using displaced-vertex topology and particle identification to suppress background. The RpPb is found to be consistent with unity within 15-20% across 1<pT<24 GeV/c, with no significant species dependence, and pp references are obtained by FONLL-based energy scaling. Comparisons with models including initial-state effects (EPS09, CGC) and cold-nuclear-matter energy loss show reasonable agreement, implying that the D-meson suppression seen in Pb-Pb at similar pT is dominated by final-state interactions in hot QCD matter rather than initial-state effects.

Abstract

The $p_{\rm T}$-differential production cross sections of the prompt charmed mesons $D^0$, $D^+$, $D^{*+}$ and $D_{\rm s}^{+}$ and their charge conjugate in the rapidity interval $-0.96 < y_{\rm cms} < 0.04$ were measured in p-Pb collisions at a centre-of-mass energy $\sqrt{s_{\rm NN}} = 5.02$ TeV with the ALICE detector at the LHC. The nuclear modification factor $R_{\rm pPb}$, quantifying the D-meson yield in p-Pb collisions relative to the yield in pp collisions scaled by the number of binary nucleon-nucleon collisions, is compatible within the 15-20% uncertainties with unity in the transverse momentum interval $1 < p_{\rm T} < 24$ GeV/$c$. No significant difference among the $R_{\rm pPb}$ of the four D-meson species is observed. The results are described within uncertainties by theoretical calculations that include initial-state effects. The measurement adds experimental evidence that the modification of the momentum spectrum of D mesons observed in Pb-Pb collisions with respect to pp collisions is due to strong final-state effects induced by hot partonic matter.

Figures (4)

• Figure 1: $p_{\rm T}$-differential inclusive production cross section of prompt ${\rm D^0}$, ${\rm D^+}$, ${\rm D^{*+}}$ and ${\rm D_s^+}$ mesons in $\hbox{p--Pb}$ collisions at $\sqrt{s_{\rm NN}}=5.02~\mathrm{TeV}$. Statistical uncertainties (bars) and systematic uncertainties (boxes) are shown.
• Figure 2: $R_{\rm pPb}$ as a function of $p_{\rm T}$ for prompt ${\rm D^0}$, ${\rm D^+}$, ${\rm D^{*+}}$ and ${\rm D_s^+}$ mesons in $\hbox{p--Pb}$ collisions at $\sqrt{s_{\rm NN}}=5.02~\mathrm{TeV}$. Statistical (bars), systematic (empty boxes), and normalization (full box) uncertainties are shown.
• Figure 3: Average $R_{\rm pPb}$ of prompt ${\rm D^0}$, ${\rm D^+}$ and ${\rm D^{*+}}$ mesons as a function of $p_{\rm T}$ compared to model calculations. Statistical (bars), systematic (empty boxes), and normalization (full box) uncertainties are shown.
• Figure 4: Average $R_{\rm pPb}$ of prompt ${\rm D^0}$, ${\rm D^+}$ and ${\rm D^{*+}}$ mesons as a function of $p_{\rm T}$ compared to D-meson $R_{\rm AA}$ in the 20% most central and in the 40%-80% Pb--Pb collisions at $\sqrt{s_{\rm NN}}=2.76~\mathrm{TeV}$ from Ref. aliceDRAA. Statistical (bars), systematic (empty boxes), and normalization (full boxes) uncertainties are shown.