Nonprompt direct-photon production in Au$+$Au collisions at $\sqrt{s_{_{NN}}}=200$ GeV

The PHENIX collaboration
336 authors from 71 institutions, 26 pages, 30 figures, 4 tabels, 2014 data. Physical Review C. Plain text data tables for the points plotted in figures for this and previous PHENIX publications are (or will be) publicly available at http://www.phenix.bnl.gov/papers.html, 2022.

Abstract (data abstract)
BNL-RHIC. The measurement of the direct photon spectrum from Au$+$Au collisions at $\sqrt{s_{NN}}$ = 200 GeV is presented by the PHENIX collaboration using the external photon conversion technique for 0\%--93\% central collisions in a transverse momentum ($p_T$) range of 0.8--10 GeV/$c$. An excess of direct photons, above prompt photon production from hard scattering processes, is observed for $p_T< 6$ GeV/$c$. nonprompt direct photons are measured by subtracting the prompt component, which is estimated as $N_{coll}$-scaled direct photons from p+p collisions at 200 GeV, from the direct photon spectrum. Results are obtained for $0.8<$p_T$<6.0$ GeV/$c$ and suggest that the spectrum has an increasing inverse slope from about 0.2 GeV/$c$ to around 0.4 GeV/$c$ with increasing $p_T$. This indicates a possible sensitivity of the measurement to photons from earlier stages of the evolution of the collision. In addition, like the direct photon production, the $p_T$-integrated nonprompt direct photon yields also follow a power law scaling behavior as a function of collision system size. The exponent, $\alpha$, for the nonprompt component is found to be consistent with 1.1 with no apparent $p_T$ dependence.

  • Figure 12

    10.17182/hepdata.129292.v1/t1

    Direct photon $R_{\gamma}$, every 20% centrality

  • Figure 13

    10.17182/hepdata.129292.v1/t2

    Direct photon $R_{\gamma}$, every 10% centrality

  • Figure 14

    10.17182/hepdata.129292.v1/t3

    Invariant yield of direct photons, every 10% centrality

  • Figure 15

    10.17182/hepdata.129292.v1/t4

    Invariant yield of direct photons, every 20% centrality

  • Figure 16

    10.17182/hepdata.129292.v1/t5

    Invariant yield of nonprompt photons, every 20% centrality

  • Figure 18

    10.17182/hepdata.129292.v1/t6

    $T_{eff}$ vs charged particle multiplicity

  • Figure 19

    10.17182/hepdata.129292.v1/t7

    Integrated direct photon yield of 1-5GeV vs charged particle multiplicity

  • Figure 20

    10.17182/hepdata.129292.v1/t8

    Integrated nonprompt direct photon yield of different $p_T$ integration window vs charged particle multiplicity

  • Figure 21

    10.17182/hepdata.129292.v1/t9

    Scaling factor $\alpha$ vs charged particle multiplicity

Loading Data...

Ask a Question


Your question will be emailed to those involved with the submission. Please mention the relevant table.


Please log in to HEPData to send a question.