English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Plus annual

Presents the access of premium content as premium feature

Premium Content

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Tools annual

Global: Zendy Free Plan

Global: Zendy Tools monthly

Global: Zendy Plus monthly

PHENIX has measured the e^+e^- pair continuum in sqrt(s_NN)=200 GeV Au+Au andp+p collisions over a wide range of mass and transverse momenta. The e^+e^-yield is compared to the expectations from hadronic sources, based on PHENIXmeasurements. In the intermediate mass region, between the masses of the phiand the J/psi meson, the yield is consistent with expectations from correlatedc^bar-c production, though other mechanisms are not ruled out. In the low massregion (below the phi) the p+p inclusive mass spectrum is well described byknown contributions from light meson decays. In contrast, the Au+Au minimumbias inclusive mass spectrum in this region shows an enhancement by a factor of4.7+/-0.4(stat)+/-1.5(syst)+/-0.9(model) At low mass (m_ee<0.3 GeV/c^2) andhigh p_T (1<p_T<5 GeV/c) an enhanced e^+e^- pair yield is observed that isconsistent with production of virtual direct photons. This excess is used toinfer the yield of real direct photons. In central Au+Au collisions, the excessof the direct photon yield over the p+p is exponential in p_T, with inverseslope T=221+/-19(stat)+/-19(syst) MeV. Hydrodynamical models with initialtemperatures ranging from T_init ~=300--600 MeV at times of 0.6--0.15 fm/cafter the collision are in qualitative agreement with the direct photon data inAu+Au. For low p_T<1 GeV/c the low mass region shows a further significantenhancement that increases with centrality and has an inverse slope of T ~=100MeV. Theoretical models under predict the low mass, low p_T enhancement.

Detailed measurement of the e+e- pair continuum in p+p and Au+Au collisions at sqrt(s_NN)=200 GeV and implications for direct photon production