Sample correlations in $\Delta\phi$ ($|\Delta\eta|<$ 1.78) for 3 $<$ $p_T^{trigger}$ $<$ 6 GeV/$c$ and 1.5 GeV/$c$ $<$ $p_T^{associated}$ $<$ $p_T^{trigger}$ for 0-60% Cu+Cu at $\sqrt{s_{NN}}$ = 62.4 GeV, 0-80% Au+Au at $\sqrt{s_{NN}}$ = 62.4 GeV, 0-95% $d$+Au at $\sqrt{s_{NN}}$ = 200 GeV, 0-60% Cu+Cu at $\sqrt{s_{NN}}$ = 200 GeV, 40-80% Au+Au at $\sqrt{s_{NN}}$ = 200 GeV, and 0-12% central Au+Au at $\sqrt{s_{NN}}$ = 200 GeV. The data are averaged between positive and negative $\Delta\phi$ and reflected in the plot.

Background subtracted sample correlations for 3 $<$ $p_T^{trigger}$ $<$ 6 GeV/$c$ and 1.5 GeV/$c$ $<$ $p_T^{associated}$ $<$ $p_T^{trigger}$ on the near-side for 0-60% Cu+Cu at $\sqrt{s_{NN}}$ = 62.4 GeV, 0-80% Au+Au at $\sqrt{s_{NN}}$ = 62.4 GeV, 0-95% $d$+Au collisions at $\sqrt{s_{NN}}$ = 200 GeV, 0-60% Cu+Cu at $\sqrt{s_{NN}}$ = 200 GeV, 40-80% Au+Au at $\sqrt{s_{NN}}$ = 200 GeV and 0-12% central Au+Au at $\sqrt{s_{NN}}$ = 200 GeV. The dependence of the jet-like correlation is shown as a function of $\Delta\eta$ ($|\Delta\phi|<$ 0.78). The data are averaged between positive and negative $\Delta\eta$.

Background subtracted sample correlations for 3 $<$ $p_T^{trigger}$ $<$ 6 GeV/$c$ and 1.5 GeV/$c$ $<$ $p_T^{associated}$ $<$ $p_T^{trigger}$ on the near-side for 0-60% Cu+Cu at $\sqrt{s_{NN}}$ = 62.4 GeV, 0-80% Au+Au at $\sqrt{s_{NN}}$ = 62.4 GeV, 0-95% $d$+Au collisions at $\sqrt{s_{NN}}$ = 200 GeV, 0-60% Cu+Cu at $\sqrt{s_{NN}}$ = 200 GeV, 40-80% Au+Au at $\sqrt{s_{NN}}$ = 200 GeV and 0-12% central Au+Au at $\sqrt{s_{NN}}$ = 200 GeV. The dependence of the jet-like correlation is shown as a function of $\Delta\phi$ ($|\Delta\eta|<$ 1.78). The data are averaged between positive and negative $\Delta\phi$.

Dependence of jet-like yield on $N_{part}$ for 3 $<$ $p_T^{trigger}$ $<$ 6 GeV/$c$ and 1.5 GeV/$c$ $<$ $p_T^{associated}$ $<$ $p_T^{trigger}$ for Cu+Cu at $\sqrt{s_{NN}}$ = 62.4 GeV. 5% systematic error due to the uncertainty on the associated particle's efficiency is not shown.

Dependence of jet-like yield on $N_{part}$ for 3 $<$ $p_T^{trigger}$ $<$ 6 GeV/$c$ and 1.5 GeV/$c$ $<$ $p_T^{associated}$ $<$ $p_T^{trigger}$ for Au+Au at $\sqrt{s_{NN}}$ = 62.4 GeV. 5% systematic error due to the uncertainty on the associated particle's efficiency is not shown.

Dependence of jet-like yield on $N_{part}$ for 3 $<$ $p_T^{trigger}$ $<$ 6 GeV/$c$ and 1.5 GeV/$c$ $<$ $p_T^{associated}$ $<$ $p_T^{trigger}$ for $d$+Au at $\sqrt{s_{NN}}$ = 200 GeV. 5% systematic error due to the uncertainty on the associated particle's efficiency is not shown.

Dependence of jet-like yield on $N_{part}$ for 3 $<$ $p_T^{trigger}$ $<$ 6 GeV/$c$ and 1.5 GeV/$c$ $<$ $p_T^{associated}$ $<$ $p_T^{trigger}$ for Cu+Cu at $\sqrt{s_{NN}}$ = 200 GeV. 5% systematic error due to the uncertainty on the associated particle's efficiency is not shown.

Dependence of jet-like yield on $N_{part}$ for 3 $<$ $p_T^{trigger}$ $<$ 6 GeV/$c$ and 1.5 GeV/$c$ $<$ $p_T^{associated}$ $<$ $p_T^{trigger}$ for Au+Au at $\sqrt{s_{NN}}$ = 200 GeV. 5% systematic error due to the uncertainty on the associated particle's efficiency is not shown.

Dependence of jet-like yield on $p_T^{\mathrm{trigger}}$ for 0-60% Cu+Cu at $\sqrt{s_{NN}}$ = 62.4 GeV, 0-80% Au+Au at $\sqrt{s_{NN}}$ = 62.4 GeV, 0-95% $d$+Au collisions at $\sqrt{s_{NN}}$ = 200 GeV, 0-60% Cu+Cu at $\sqrt{s_{NN}}$ = 200 GeV, 40-80% Au+Au at $\sqrt{s_{NN}}$ = 200 GeV and 0-12% central Au+Au at $\sqrt{s_{NN}}$ = 200 GeV. The 5% systematic error due to the uncertainty on the associated particle's efficiency is not shown.

Dependence of jet-like yield on $p_T^{\mathrm{associated}}$ for 3 $<$ $p_T^{trigger}$ $<$ 6 GeV/$c$ for 0-60% Cu+Cu and 0-80% Au+Au collisions at $\sqrt{s_{NN}}$ = 62.4 GeV and 0-95% $d$+Au, 0-60% Cu+Cu, 0-12% Au+Au and 40-80% Au+Au collisions at $\sqrt{s_{NN}}$ = 200 GeV. The 5% systematic error due to the uncertainty on the associated particle's efficiency is not shown.

Dependence of the widths in $\Delta\phi$ on $p_T^{\mathrm{trigger}}$ for 1.5 GeV/$c$ $<$ $p_T^{associated}$ $<$ $p_T^{trigger}$ for 0-95% $d$+Au, 0-60% Cu+Cu at $\sqrt{s_{NN}}$ = 62.4 GeV and $\sqrt{s_{NN}}$ = 200 GeV, 0-80% Au+Au at $\sqrt{s_{NN}}$ = 62.4 GeV, and 0-12% and 40-80% Au+Au at $\sqrt{s_{NN}}$ = 200 GeV.

Dependence of the widths in $\Delta\phi$ on $p_T^{\mathrm{associated}}$ for 3 $<$ $p_T^{trigger}$ $<$ 6 GeV/$c$ for 0-95% $d$+Au, 0-60% Cu+Cu at $\sqrt{s_{NN}}$ = 62.4 GeV and $\sqrt{s_{NN}}$ = 200 GeV, 0-80% Au+Au at $\sqrt{s_{NN}}$ = 62.4 GeV, and 0-12% and 40-80% Au+Au at $\sqrt{s_{NN}}$ = 200 GeV.

Dependence of the widths in $\Delta\phi$ on $N_{part}$ for 3 $<$ $p_T^{trigger}$ $<$ 6 GeV/$c$ and 1.5 GeV/$c$ $<$ $p_T^{associated}$ $<$ $p_T^{trigger}$ for 0-60% Cu+Cu at $\sqrt{s_{NN}}$ = 62.4 GeV.

Dependence of the widths in $\Delta\phi$ on $N_{part}$ for 3 $<$ $p_T^{trigger}$ $<$ 6 GeV/$c$ and 1.5 GeV/$c$ $<$ $p_T^{associated}$ $<$ $p_T^{trigger}$ for 0-80% Au+Au at $\sqrt{s_{NN}}$ = 62.4 GeV.

Dependence of the widths in $\Delta\phi$ on $N_{part}$ for 3 $<$ $p_T^{trigger}$ $<$ 6 GeV/$c$ and 1.5 GeV/$c$ $<$ $p_T^{associated}$ $<$ $p_T^{trigger}$ for 0-95% $d$+Au at $\sqrt{s_{NN}}$ = 200 GeV.

Dependence of the widths in $\Delta\phi$ on $N_{part}$ for 3 $<$ $p_T^{trigger}$ $<$ 6 GeV/$c$ and 1.5 GeV/$c$ $<$ $p_T^{associated}$ $<$ $p_T^{trigger}$ for 0-60% Cu+Cu at $\sqrt{s_{NN}}$ = 200 GeV.

Dependence of the widths in $\Delta\phi$ on $N_{part}$ for 3 $<$ $p_T^{trigger}$ $<$ 6 GeV/$c$ and 1.5 GeV/$c$ $<$ $p_T^{associated}$ $<$ $p_T^{trigger}$ for Au+Au at $\sqrt{s_{NN}}$ = 200 GeV.

Dependence of the widths in $\Delta\eta$ on $p_T^{\mathrm{trigger}}$ for 1.5 GeV/$c$ $<$ $p_T^{associated}$ $<$ $p_T^{trigger}$ for 0-95% $d$+Au, 0-60% Cu+Cu at $\sqrt{s_{NN}}$ = 62.4 GeV and $\sqrt{s_{NN}}$ = 200 GeV, 0-80% Au+Au at $\sqrt{s_{NN}}$ = 62.4 GeV, and 0-12% and 40-80% Au+Au at $\sqrt{s_{NN}}$ = 200 GeV.

Dependence of the widths in $\Delta\eta$ on $p_T^{\mathrm{associated}}$ for 3 $<$ $p_T^{trigger}$ $<$ 6 GeV/$c$ for 0-95% $d$+Au, 0-60% Cu+Cu at $\sqrt{s_{NN}}$ = 62.4 GeV and $\sqrt{s_{NN}}$ = 200 GeV, 0-80% Au+Au at $\sqrt{s_{NN}}$ = 62.4 GeV, and 0-12% and 40-80% Au+Au at $\sqrt{s_{NN}}$ = 200 GeV.

Dependence of the widths in $\Delta\eta$ on $N_{part}$ for 3 $<$ $p_T^{trigger}$ $<$ 6 GeV/$c$ and 1.5 GeV/$c$ $<$ $p_T^{associated}$ $<$ $p_T^{trigger}$ for 0-60% Cu+Cu at $\sqrt{s_{NN}}$ = 62.4 GeV.

Dependence of the widths in $\Delta\eta$ on $N_{part}$ for 3 $<$ $p_T^{trigger}$ $<$ 6 GeV/$c$ and 1.5 GeV/$c$ $<$ $p_T^{associated}$ $<$ $p_T^{trigger}$ for 0-80% Au+Au at $\sqrt{s_{NN}}$ = 62.4 GeV.

Dependence of the widths in $\Delta\eta$ on $N_{part}$ for 3 $<$ $p_T^{trigger}$ $<$ 6 GeV/$c$ and 1.5 GeV/$c$ $<$ $p_T^{associated}$ $<$ $p_T^{trigger}$ for 0-95% $d$+Au at $\sqrt{s_{NN}}$ = 200 GeV.

Dependence of the widths in $\Delta\eta$ on $N_{part}$ for 3 $<$ $p_T^{trigger}$ $<$ 6 GeV/$c$ and 1.5 GeV/$c$ $<$ $p_T^{associated}$ $<$ $p_T^{trigger}$ for 0-60% Cu+Cu at $\sqrt{s_{NN}}$ = 200 GeV.

Dependence of the widths in $\Delta\eta$ on $N_{part}$ for 3 $<$ $p_T^{trigger}$ $<$ 6 GeV/$c$ and 1.5 GeV/$c$ $<$ $p_T^{associated}$ $<$ $p_T^{trigger}$ for Au+Au at $\sqrt{s_{NN}}$ = 200 GeV.

Dependence of ridge yield on $N_{part}$ for 3 $<$ $p_T^{trigger}$ $<$ 6 GeV/$c$ and 1.5 GeV/$c$ $<$ $p_T^{associated}$ $<$ $p_T^{trigger}$ for Cu+Cu at $\sqrt{s_{NN}}$ = 62.4 GeV.

Dependence of ridge yield on $N_{part}$ for 3 $<$ $p_T^{trigger}$ $<$ 6 GeV/$c$ and 1.5 GeV/$c$ $<$ $p_T^{associated}$ $<$ $p_T^{trigger}$ for Au+Au at $\sqrt{s_{NN}}$ = 62.4 GeV.

Dependence of ridge yield on $N_{part}$ for 3 $<$ $p_T^{trigger}$ $<$ 6 GeV/$c$ and 1.5 GeV/$c$ $<$ $p_T^{associated}$ $<$ $p_T^{trigger}$ for Cu+Cu at $\sqrt{s_{NN}}$ = 200 GeV.

Dependence of ridge yield on $N_{part}$ for 3 $<$ $p_T^{trigger}$ $<$ 6 GeV/$c$ and 1.5 GeV/$c$ $<$ $p_T^{associated}$ $<$ $p_T^{trigger}$ for Au+Au at $\sqrt{s_{NN}}$ = 200 GeV.

Ratio of the ridge and jet-like yields on $N_{part}$ for 3 $<$ $p_T^{trigger}$ $<$ 6 GeV/$c$ and 1.5 GeV/$c$ $<$ $p_T^{associated}$ $<$ $p_T^{trigger}$ for Cu+Cu at $\sqrt{s_{NN}}$ = 62.4 GeV.

Ratio of the ridge and jet-like yields on $N_{part}$ for 3 $<$ $p_T^{trigger}$ $<$ 6 GeV/$c$ and 1.5 GeV/$c$ $<$ $p_T^{associated}$ $<$ $p_T^{trigger}$ for Au+Au at $\sqrt{s_{NN}}$ = 62.4 GeV.

Ratio of the ridge and jet-like yields on $N_{part}$ for 3 $<$ $p_T^{trigger}$ $<$ 6 GeV/$c$ and 1.5 GeV/$c$ $<$ $p_T^{associated}$ $<$ $p_T^{trigger}$ for Cu+Cu at $\sqrt{s_{NN}}$ = 200 GeV.

Ratio of the ridge and jet-like yields on $N_{part}$ for 3 $<$ $p_T^{trigger}$ $<$ 6 GeV/$c$ and 1.5 GeV/$c$ $<$ $p_T^{associated}$ $<$ $p_T^{trigger}$ for Au+Au at $\sqrt{s_{NN}}$ = 200 GeV.

Dependence of $V_{3\Delta}/V_{2\Delta}$ on $N_{part}$ for 3 $<$ $p_T^{trigger}$ $<$ 6 GeV/$c$ and 1.5 GeV/$c$ $<$ $p_T^{associated}$ $<$ $p_T^{trigger}$ for Cu+Cu at $\sqrt{s_{NN}}$ = 62.4 GeV.

Dependence of $V_{3\Delta}/V_{2\Delta}$ on $N_{part}$ for 3 $<$ $p_T^{trigger}$ $<$ 6 GeV/$c$ and 1.5 GeV/$c$ $<$ $p_T^{associated}$ $<$ $p_T^{trigger}$ for Au+Au at $\sqrt{s_{NN}}$ = 62.4 GeV.

Dependence of $V_{3\Delta}/V_{2\Delta}$ on $N_{part}$ for 3 $<$ $p_T^{trigger}$ $<$ 6 GeV/$c$ and 1.5 GeV/$c$ $<$ $p_T^{associated}$ $<$ $p_T^{trigger}$ for $d$+Au at $\sqrt{s_{NN}}$ = 200 GeV.

Dependence of $V_{3\Delta}/V_{2\Delta}$ on $N_{part}$ for 3 $<$ $p_T^{trigger}$ $<$ 6 GeV/$c$ and 1.5 GeV/$c$ $<$ $p_T^{associated}$ $<$ $p_T^{trigger}$ for Cu+Cu at $\sqrt{s_{NN}}$ = 200 GeV.

Dependence of $V_{3\Delta}/V_{2\Delta}$ on $N_{part}$ for 3 $<$ $p_T^{trigger}$ $<$ 6 GeV/$c$ and 1.5 GeV/$c$ $<$ $p_T^{associated}$ $<$ $p_T^{trigger}$ for Au+Au at $\sqrt{s_{NN}}$ = 200 GeV.

FIG. 4. Ridge yield Eq. (9) in $|\Delta \eta|<1.7$ and $2 \mathrm{GeV/c}<p^{assoc}_{t}$ < $p^{trig}_{t}$ as a function of $p_{t}^{t r i g}$. Solid lines are the systematic uncertainty due to $v_{2}$.

FIG. 5. Projection of $d N /\left.d \Delta \phi\right|_{a, b}$ for $0.7<|\Delta \eta|<1.4$ [Eq. (3)] in two trigger $p_{t}$ windows for $2<p_{t}^{\text {assoc }}<4 \mathrm{GeV} / \mathrm{c} .$ No background subtraction has been applied; note the suppressed zero on the vertical scale. The shaded band shows the fit of the function $k_{1}+k_{2}$. $\cos (2 \Delta \phi)$ to the recoil region $2<|\Delta \phi|<\pi$ for $4<p_{t}^{\text {trig }}<6 \mathrm{GeV} / c$. The width of the band indicates the fitting error. The solid curve represents the background estimate using the ZYAM normalization for $4<p_{t}^{\text {trig }}<6 \mathrm{GeV} / c .$ Systematic uncertainties are indicated by the light shaded band.

FIG. 6. (Color online) Differential $p_{t}$ spectrum for associated particles in central $\mathrm{Au}+$ Au collisions, with $4<p_{t}^{\text {trig }}<6$ and $6<p_{t}^{\text {trig }}<10 \mathrm{GeV} / c$ . The dash-dotted line is the inclusive hadron spectrum from central $\mathrm{Au}+$ Au collisions $[1] .$ Left panel: ridge spectrum; shaded bands show systematic uncertainty. Right panel: jet-like spectrum, also compared to $d+$ Au reference measurements. The lines in both panels show exponential fits to the data (see Table III). Data are offset horizontally for clarity.

FIG. 6. (Color online) Differential $p_{t}$ spectrum for associated particles in central $\mathrm{Au}+$ Au collisions, with $4<p_{t}^{\text {trig }}<6$ and $6<p_{t}^{\text {trig }}<10 \mathrm{GeV} / c$ . The dash-dotted line is the inclusive hadron spectrum from central $\mathrm{Au}+$ Au collisions $[1] .$ Left panel: ridge spectrum; shaded bands show systematic uncertainty. Right panel: jet-like spectrum, also compared to $d+$ Au reference measurements. The lines in both panels show exponential fits to the data (see Table III). Data are offset horizontally for clarity.

The $\pi^0$ invariant mass peak positions and widths as a function of $p_{T}$ in 0-80% Au+Au collisions at $\sqrt{s_{NN}}=200$ GeV.

The $\pi^0$ invariant mass peak positions and widths as a function of $p_{T}$ in 0-80% Au+Au collisions at $\sqrt{s_{NN}}=200$ GeV.

The $\pi^0$ invariant mass peak positions and widths as a function of $p_{T}$ in 0-80% Au+Au collisions at $\sqrt{s_{NN}}=200$ GeV.

The $\pi^0$ invariant mass peak positions and widths as a function of $p_{T}$ in 0-80% Au+Au collisions at $\sqrt{s_{NN}}=200$ GeV.

The $\pi^0$ invariant mass peak positions and widths as a function of $p_{T}$ in 0-80% Au+Au collisions at $\sqrt{s_{NN}}=200$ GeV.

The $\pi^0$ invariant mass peak positions and widths as a function of $p_{T}$ in 0-80% Au+Au collisions at $\sqrt{s_{NN}}=200$ GeV.

Photon conversion point radius distribution from real data and MC simulation in Au+Au collisions at $\sqrt{s_{NN}}=200$ GeV.

Conversion probability correction factor for $\pi^0$ as a function of $p_{T}$

The overall detection efficiency of $\pi^0$ from embedding studt in 0-80% Au+Au collisions at $\sqrt{s_{NN}}=200$ GeV.

The overall detection efficiency of $\pi^0$ from embedding studt in 0-80% Au+Au collisions at $\sqrt{s_{NN}}=200$ GeV.

The overall detection efficiency of $\pi^0$ from embedding studt in 0-80% Au+Au collisions at $\sqrt{s_{NN}}=200$ GeV.

Invariant yield of STAR $\pi^0$ as a function of $p_{T}$ at midrapidity for different collision centrality bins in Au+Au collisions at $\sqrt{s_{NN}}=200$ GeV.

Invariant yield of STAR $\pi^0$ as a function of $p_{T}$ at midrapidity for different collision centrality bins in Au+Au collisions at $\sqrt{s_{NN}}=200$ GeV.

Invariant yield of STAR $\pi^0$ as a function of $p_{T}$ at midrapidity for different collision centrality bins in Au+Au collisions at $\sqrt{s_{NN}}=200$ GeV.

The ratios of STAR $\pi^0$ spectra over $\pi^{\pm}$ from STAR and $\pi^0$ from PHENIX for different collision centrality bins in Au+Au collisions at $\sqrt{s_{NN}}=200$ GeV.

The nuclear modification factor $R_{CP}$ as a functon of $p_{T}$ of STAR $\pi^0$ in Au+Au collisions at $\sqrt{s_{NN}}=200$ GeV.

The nuclear modification factor $R_{AA}$ as a functon of $p_{T}$ of STAR $\pi^0$ in Au+Au collisions at $\sqrt{s_{NN}}=200$ GeV.