Measurement of jet-medium interactions via direct photon-hadron correlations in Au$+$Au and $d$ $+$Au collisions at $\sqrt{s_{_{NN}}}=200$ GeV

The collaboration
Phys.Rev.C 102 (2020) 054910, 2020.

Abstract (data abstract)
BNL-RHIC. We present direct photon-hadron correlations in 200 GeV/A Au+Au, d+Au and p+p collisions, for direct photon $p_T$ from 5-12 GeV/$c$, collected by the PHENIX Collaboration in the years from 2006 to 2011. We observe no significant modification of jet fragmentation in d+Au collisions, indicating that cold nuclear matter effects are small or absent. Hadrons carrying a large fraction of the quark's momentum are suppressed in Au+Au compared to p+p and d+Au. As the momentum fraction decreases, the yield of hadrons in Au+Au increases to an excess over the yield in p+p collisions. The excess is at large angles and at low hadron $p_T$ and is most pronounced for hadrons associated with lower momentum direct photons. Comparison to theoretical calculations suggests that the hadron excess arises from medium response to energy deposited by jets.

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Per-trigger yield of hadrons associated to direct photons in Au+Au collisions for direct photon $p_T$ 5-9 GeV/$c$, compared with p+p...

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Per-trigger yield of hadrons associated to direct photons in d+Au collisions for direct photon $p_T$ 7-9 GeV/$c$, compared with p+p...

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Integrated away-side $\gamma_{dir}$-h per-trigger yields of Au+Au, d+Au, and p+p, as a function of $\xi$.

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Integrated away-side $\gamma_{dir}$-h per-trigger $I_{AA}$ and $I_{dA}$ of Au+Au, d+Au, and p+p, as a function of $\xi$.

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$I_{AA}$ vs $\xi$ for direct photon $p_{T}^{\gamma}$ of 5-7 GeV/$c$, 7-9 GeV/$c$, and 9-12 GeV/$c$.

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$I_{AA}$ vs $\xi$ for direct photon $p_{T}^{\gamma}$ of 5-7 GeV/$c$, 7-9 GeV/$c$, and 9-12 GeV/$c$.

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$I_{AA}$ vs $\xi$ for direct photon $p_{T}^{\gamma}$ of 5-7 GeV/$c$, 7-9 GeV/$c$, and 9-12 GeV/$c$.

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$I_{AA}$ as a function of $\xi$ for direct photon $p_{T}^{\gamma}$ of 5-7, 7-9, and 9-12 GeV/$c$. Three away-side integration ranges...

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$I_{AA}$ as a function of $\xi$ for direct photon $p_{T}^{\gamma}$ of 5-7, 7-9, and 9-12 GeV/$c$. Three away-side integration ranges...

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$I_{AA}$ as a function of $\xi$ for direct photon $p_{T}^{\gamma}$ of 5-7, 7-9, and 9-12 GeV/$c$. Three away-side integration ranges...

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Ratios of $I_{AA}$ as a function of direct photon $p_T$ for three different away-side integration ranges.

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Measured $I_{AA}$ for direct photon $p_T$ of 5-7, 7-9, and 9-12 GeV/$c$, as a function of $\xi$, are compared with...

• #### Figure 8b

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Measured $I_{AA}$ for direct photon $p_T$ of 5-7, 7-9, and 9-12 GeV/$c$, as a function of $\xi$, are compared with...

• #### Figure 8c

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Measured $I_{AA}$ for direct photon $p_T$ of 5-7, 7-9, and 9-12 GeV/$c$, as a function of $\xi$, are compared with...