Measurement of azimuthal correlations of D mesons with charged particles in pp collisions at [Formula: see text] TeV and p-Pb collisions at [Formula: see text] TeV

Abstract

The azimuthal correlations of D mesons with charged particles were measured with the ALICE apparatus in pp collisions at [Formula: see text] and p-Pb collisions at [Formula: see text] at the Large Hadron Collider. [Formula: see text], [Formula: see text], and [Formula: see text] mesons and their charge conjugates with transverse momentum [Formula: see text] and rapidity in the nucleon-nucleon centre-of-mass system [Formula: see text] (pp collisions) and [Formula: see text] (p-Pb collisions) were correlated to charged particles with [Formula: see text]. The yield of charged particles in the correlation peak induced by the jet containing the D meson and the peak width are compatible within uncertainties in the two collision systems. The data are described within uncertainties by Monte-Carlo simulations based on PYTHIA, POWHEG, and EPOS 3 event generators.

Fig. 1

Distributions of ${\mathrm{D}}^0$ (left column) and ${\mathrm{D}}^{+}$ (middle column) candidate invariant mass and of the ${\mathrm{D}}^{\ast +}$ candidate invariant-mass difference (right column). The distributions are shown for pp collisions in the $3<p_{\mathrm{T}}<5\mathrm{GeV}/c$ range (top row) and for p–Pb collisions in the $5<p_{\mathrm{T}}<8\mathrm{GeV}/c$ (middle row) and $8<p_{\mathrm{T}}<16\mathrm{GeV}/c$ (bottom row) ranges. The fits to the invariant mass distributions and the Gaussian mean and sigma values are also shown

Fig. 2

Comparison of the azimuthal-correlation distributions of D mesons with charged particles obtained for ${\mathrm{D}}^0$, ${\mathrm{D}}^{+}$ and ${\mathrm{D}}^{\ast +}$ mesons for $5<p_{\mathrm{T}}^{\mathrm{D}}<8\mathrm{GeV}/c$, $p_{\mathrm{T}}^{\mathrm{assoc}}>1\mathrm{GeV}/c$ in pp collisions at $\sqrt{s}=7\mathrm{TeV}$ (left panel) and for $8<p_{\mathrm{T}}^{\mathrm{D}}<16\mathrm{GeV}/c$, $p_{\mathrm{T}}^{\mathrm{assoc}}>1\mathrm{GeV}/c$ in $\text{p--Pb}$ collisions at $\sqrt{s_{\mathrm{NN}}}=5.02\mathrm{TeV}$ (right panel). The statistical uncertainties are shown as error bars, the $\mathrm{\Delta }\mathit{\phi }$-uncorrelated systematic uncertainties as boxes, while the part of systematic uncertainty correlated in $\mathrm{\Delta }\mathit{\phi }$ is reported as text (scale uncertainty). The latter is largely uncorrelated among the D-meson species

Fig. 3

Average of the azimuthal-correlation distributions of ${\mathrm{D}}^0$, ${\mathrm{D}}^{+}$ and ${\mathrm{D}}^{\ast +}$ mesons with $3<p_{\mathrm{T}}^{\mathrm{D}}<5\mathrm{GeV}/c$ (left column), $5<p_{\mathrm{T}}^{\mathrm{D}}<8\mathrm{GeV}/c$ (middle column), and $8<p_{\mathrm{T}}^{\mathrm{D}}<16\mathrm{GeV}/c$ (right column), with charged particles with $p_{\mathrm{T}}^{\mathrm{assoc}}>0.3\mathrm{GeV}/c$ (top row), $0.3<p_{\mathrm{T}}^{\mathrm{assoc}}<1\mathrm{GeV}/c$ (middle row), and $p_{\mathrm{T}}^{\mathrm{assoc}}>1\mathrm{GeV}/c$ (bottom row), measured in pp collisions at $\sqrt{s}=7\mathrm{TeV}$ and in p–Pb collisions at $\sqrt{s_{\mathrm{NN}}}=5.02\mathrm{TeV}$. The statistical uncertainties are shown as error bars, the $\mathrm{\Delta }\mathit{\phi }$-uncorrelated systematic uncertainties as boxes, while the part of systematic uncertainty correlated in $\mathrm{\Delta }\mathit{\phi }$ is reported as text (scale uncertainty)

Fig. 4

Comparison of the azimuthal-correlation distributions of D mesons with $5<p_{\mathrm{T}}^{\mathrm{D}}<8\mathrm{GeV}/c$ (left column) and $8<p_{\mathrm{T}}^{\mathrm{D}}<16\mathrm{GeV}/c$ (right column) with charged particles with $p_{\mathrm{T}}^{\mathrm{assoc}}>0.3\mathrm{GeV}/c$ (top row), $0.3<p_{\mathrm{T}}^{\mathrm{assoc}}<1\mathrm{GeV}/c$ (middle row), and $p_{\mathrm{T}}^{\mathrm{assoc}}>1\mathrm{GeV}/c$ (bottom row) in pp collisions at $\sqrt{s}=7\mathrm{TeV}$ and in p–Pb collisions at $\sqrt{s_{\mathrm{NN}}}=5.02\mathrm{TeV}$, after baseline subtraction. The statistical uncertainties are shown as error bars, the $\mathrm{\Delta }\mathit{\phi }$-uncorrelated systematic uncertainties as boxes around the data points, the part of systematic uncertainty correlated in $\mathrm{\Delta }\mathit{\phi }$ is reported as text (scale uncertainty), the uncertainties deriving from the subtraction of the baselines are represented by the boxes at $\mathrm{\Delta }\mathit{\phi }>\mathit{\pi }$

Fig. 5

Examples of the fit to the azimuthal-correlation distribution, for D mesons with $5<p_{\mathrm{T}}^{\mathrm{D}}<8\mathrm{GeV}/c$ with charged particles with $p_{\mathrm{T}}^{\mathrm{assoc}}>1\mathrm{GeV}/c$ in pp collisions at $\sqrt{s}=7\mathrm{TeV}$ (left), and for D mesons with $8<p_{\mathrm{T}}^{\mathrm{D}}<16\mathrm{GeV}/c$ with charged particles with $p_{\mathrm{T}}^{\mathrm{assoc}}>1\mathrm{GeV}/c$ in p–Pb collisions at $\sqrt{s_{\mathrm{NN}}}=5.02\mathrm{TeV}$ (right). The statistical uncertainties are shown as error bars, the $\mathrm{\Delta }\mathit{\phi }$-uncorrelated systematic uncertainties as boxes, while the part of systematic uncertainty correlated in $\mathrm{\Delta }\mathit{\phi }$ is reported as text (scale uncertainty). The terms of the fit function described in Sect. 3.3 are also shown separately: near-side Gaussian function (blue dashed line), away-side Gaussian function (green dashed–dotted line) and baseline constant term (magenta dotted line)

Fig. 6

Comparison of the near-side peak associated yield (top row) and peak width (bottom row) in pp and $\text{p--Pb}$ collisions as a function of $p_{\mathrm{T}}^{\mathrm{D}}$, for $p_{\mathrm{T}}^{\mathrm{assoc}}>0.3\mathrm{GeV}/c$ (left column), $0.3<p_{\mathrm{T}}^{\mathrm{assoc}}<1\mathrm{GeV}/c$ (middle column), and $p_{\mathrm{T}}^{\mathrm{assoc}}>1\mathrm{GeV}/c$ (right column). The points and error boxes for p–Pb collisions are shifted by $\mathrm{\Delta }{p}_{\mathrm{T}}=+0.3\mathrm{GeV}/c$. Statistical and systematic uncertainties are shown as error bars and boxes, respectively

Fig. 7

Comparison of $\mathrm{\Delta }\mathit{\phi }$-correlation distributions of D mesons with charged particles measured in pp collisions at $\sqrt{s}=7\mathrm{TeV}$ and Monte-Carlo simulations performed with different event generators, after the subtraction of the baseline. The statistical and systematic uncertainties of the measured distributions are displayed as in Fig. 4

Fig. 8

Comparison of near-side peak associated yield (top row), near-side peak width (middle row), and baseline (bottom row) values measured in pp collisions at $\sqrt{s}=7\mathrm{TeV}$ with the expectations from simulations performed with different Monte-Carlo event generators. Statistical and systematic uncertainties are shown as error bars and boxes, respectively

Fig. 9

Comparison of near-side peak associated yield (top row) and near-side peak width (bottom row) values measured in p–Pb collisions at $\sqrt{s_{\mathrm{NN}}}=5.02\mathrm{TeV}$ with the expectations from simulations performed with different Monte-Carlo event generators. Statistical and systematic uncertainties are shown as error bars and boxes, respectively