Azimuthal correlations of electrons from heavy-flavor decay with hadrons in $p$$+$$p$ and Au$+$Au collisions at $\sqrt{s_{\mathit{NN}}}=200$ GeV

Measurements of electrons from the decay of open-heavy-flavor mesons have shown that the yields are suppressed in Au$+$Au collisions compared to expectations from binary-scaled $p$$+$$p$ collisions. These measurements indicate that charm and bottom quarks interact with the hot dense matter produced in heavy-ion collisions much more than expected. Here we extend these studies to two-particle correlations where one particle is an electron from the decay of a heavy-flavor meson and the other is a charged hadron from either the decay of the heavy meson or from jet fragmentation. These measurements provide more detailed information about the interactions between heavy quarks and the matter, such as whether the modification of the away-side-jet shape seen in hadron-hadron correlations is present when the trigger particle is from heavy-meson decay and whether the overall level of away-side-jet suppression is consistent. We statistically subtract correlations of electrons arising from background sources from the inclusive electron-hadron correlations and obtain two-particle azimuthal correlations at $\sqrt{s_{\mathit{NN}}}=200$ GeV between electrons from heavy-flavor decay with charged hadrons in $p$$+$$p$ and also first results in Au$+$Au collisions. We find the away-side-jet shape and yield to be modified in Au$+$Au collisions compared to $p$$+$$p$ collisions.

Figure 1

Weights ($w$) for electrons with $1.5<p_T<2.0$ GeV/$c$ from the method using Dalitz decays (histogram) and photon conversions (solid points) as a function of the photon $p_T$.

Figure 2

$e_{\mathrm{bkg}}$-$h$ (top panel) and $e_{\mathrm{HF}}$-$h$ (bottom panel) conditional yields for $p$$+$$p$ collisions with $1.5<p_{T,e}<2.0$ GeV/$c$ and $1.5<p_{T,h}<2.0$ GeV/$c$ for the two methods of constructing $e_{\mathrm{bkg}}$-$h$ conditional yields: the conversion method (solid circles) and the Dalitz decay method (black squares). Points have been offset slightly for clarity.

Figure 3

pythia $e_{J/\Psi }$-$h$ correlations after ZYAM subtraction for electrons with $3.0<p_T<3.5$ GeV/$c$ and hadrons with $0.5<p_T<1.0$ GeV/$c$. The central values are from the default pythia $J/\Psi$ production setting and the lines show the systematic uncertainty set by the magnitude of the maximal deviation between the default setting at the color singlet and color octet production settings.

Figure 4

$e_{\mathrm{inc}}$-$h$, $e_{\mathrm{bkg}}$-$h$, and $e_{\mathrm{HF}}$-$h$ (solid circles) for $p$$+$$p$ (top panel) and Au$+$Au (bottom panel) collisions for $2.0<p_{T,e}<3.0$ GeV/$c$ and $1.5<p_{T,h}<2.0$ GeV/$c$. The overall normalization uncertain of 7.9% in $p$$+$$p$ and 9.4% in Au$+$Au is not shown.

Figure 5

Near (top) and away (bottom) side conditional yields in $p$$+$$p$ collisions as a function of hadron $p_T$. $e_{\mathrm{inc}}$ triggers are shown as triangles, $e_{\mathrm{bkg}}$ triggers are shown as open circles, and $e_{\mathrm{HF}}$ triggers are shown as solid circles. The boxes on the $e_{\mathrm{HF}}$-$h$ points are the systematic uncertainties except for the overall normalization uncertainty of 7.9%, which is not shown.

Figure 6

Near-side $e_{\mathrm{HF}}$-$h$ conditional yields in $p$$+$$p$ collisions (solid points) as a function of the associated hadron $p_T$. For comparison hadron-hadron conditional yields in $p$$+$$p$ collisions from Ref. [14] are also shown (the $\Delta \varphi$ range for the hadron-hadron yields is $\Delta \varphi <\pi /3$). The associated hadron $p_T$ spectra are harder for $e_{\mathrm{HF}}$-$h$ than hadron-hadron conditional yields at the same $p_{T,\mathrm{trig}}$ range (the highest $p_T$ trigger selection is for 4.0–4.5 GeV/$c$ for the $e_{\mathrm{HF}}$ triggers and 4.0–5.0 GeV/$c$ for the hadron triggers). The overall normalization uncertainty of 7.9% is not shown.

Figure 7

Gaussian widths of near-side conditional yields as a function of the associated hadron $p_T$ for four $p_{T,e}$ selections. Solid circles show results from $e_{\mathrm{HF}}$-$h$ correlations and triangles show results from $h$-$h$ correlations. Crosses are from powheg [28] with charm and bottom combined according to FONLL calculations [31].

Figure 8

Away-side $e_{\mathrm{HF}}$-$h$ ($2.51<\Delta \varphi <\pi$) conditional yields in $p$$+$$p$ collisions (solid points) as a function of the associated hadron $p_T$. For comparison hadron-hadron conditional yields in $p$$+$$p$ collisions from Ref. [14] are also shown (the $\Delta \varphi$ range for the hadron-hadron yields is $2.51\Delta \varphi <\pi$). The associated hadron $p_T$ spectra are harder for $e_{\mathrm{HF}}$-$h$ than hadron-hadron conditional yields at the same $p_{T,\mathrm{trig}}$ range (the highest $p_T$ trigger selection is for 4.0–4.5 GeV/$c$ for the $e_{\mathrm{HF}}$ triggers and 4.0–5.0 GeV/$c$ for the hadron triggers). The overall normalization uncertainty of 7.9% is not shown.

Figure 9

Inverse slope of the $e_{\mathrm{HF}}$ triggered away-side conditional hadron $p_T$ distributions shown in Fig. 8 as a function of $p_T$ of the trigger particle. For comparison fits to the hadron-hadron data from Ref. [14] are also shown.

Figure 10

Near-side ($0<\Delta \varphi <1.25$ rad) integrated yield for Au$+$Au (solid circles) and $p$$+$$p$ collisions (open circles) for $2.0<p_{T,e}<3.0$ GeV/$c$ (top panel) and $3.0<p_{T,e}<4.0$ GeV/$c$ (bottom panel) as a function of the associated hadron $p_T$. The overall normalization uncertainty of 9.4% in Au$+$Au and 7.9% in $p$$+$$p$ is not shown. Points are slightly shifted horizontally for clarity.

Figure 11

Near-side ($0<\Delta \varphi <1.25$ rad) $I_{\mathrm{AA}}$ for $2.0<p_{T,e}<3.0$ GeV/$c$ (top panel) and $3.0<p_{T,e}<4.0$ GeV/$c$ (bottom panel) as a function of the associated hadron $p_T$ for $e_{\mathrm{HF}}$ (solid points) and hadron (open points) triggers (from Ref. [14]). The gray band around unity shows the overall normalization uncertainty (12.4%), which moves all points together. Points are slightly shifted horizontally for clarity.

Figure 12

Away-side conditional yields for wide (left) and narrow (right) away-side $\Delta \varphi$ integration ranges for Au$+$Au (solid points) and $p$$+$$p$ (open points). Top panels show $2.0<p_{T,e}<3.0$ GeV/$c$ and bottom panels shown $3.0<p_{T,e}<4.0$ GeV/$c$. Upper limits are for 90% confidence levels. The overall normalization uncertainty of 9.4% in Au$+$Au and 7.9% in $p$$+$$p$ are not shown. Points are slightly shifted horizontally for clarity.

Figure 13

$I_{\mathrm{AA}}$ as determined from the away-side yields in Fig. 12. Two $\Delta \varphi$ ranges are shown: $1.25<\Delta \varphi <\pi$ rad (left panels) and $2.51<\Delta \varphi <\pi$ rad (right panels). The gray band around unity shows the overall normalization uncertainty of 12.4%, which moves all points together. For comparison hadron-hadron $I_{\mathrm{AA}}$ values from Ref. [14] are also shown for trigger $p_T$ selections where the parent heavy meson has similar $p_T$ to the trigger light hadron (see Table 3). Points are slightly shifted horizontally for clarity. The solid horizontal line is at 0 and the dashed horizontal line is at 1.

Figure 14

Ratio of the yield in the head region per radian to that in the shoulder region per radian for Au$+$Au (black) and $p$$+$$p$ (red).

Figure 15

$e_{\mathrm{HF}}$-$h$ jet functions for Au$+$Au (solid blue circles) and $p$$+$$p$ collisions for 2.0–3.0 GeV/$c$ electron triggers and the hadron-$p_T$ bins indicated.

Figure 16

$e_{\mathrm{HF}}$-$h$ jet functions for Au$+$Au (solid blue circles) and $p$$+$$p$ collisions for 3.0–4.0 GeV/$c$ electron triggers and the hadron-$p_T$ bins indicated.

Figure 17

$e_{\mathrm{HF}}$-$h$ jet functions in $p$$+$$p$ collisions for 1.5–2.0 GeV/$c$ electron triggers and the hadron-$p_T$ bins indicated.

Figure 18

$e_{\mathrm{HF}}$-$h$ jet functions in $p$$+$$p$ collisions for 2.0–3.0 GeV/$c$ electron triggers and the hadron-$p_T$ bins indicated.

Figure 19

$e_{\mathrm{HF}}$-$h$ jet functions in $p$$+$$p$ collisions for 3.0–4.0 GeV/$c$ electron triggers and the hadron-$p_T$ bins indicated.

Figure 20

$e_{\mathrm{HF}}$-$h$ jet functions in $p$$+$$p$ collisions for 4.0–4.5 GeV/$c$ electron triggers and the hadron-$p_T$ bins indicated.