PHENIX Results on In-Medium Jet Modification Using $\pi^0$ and Direct Photon-Triggered Two-Particle Correlations

Jun 2, 2020, 7:30 AM
1h 20m


Poster Jets and High Momentum Hadrons Poster session


Anthony Hodges (Georgia State University)


     Jets in $A+A$ collisions are modified both in terms of their particle yield and that they appear broader when compared to their counterparts in $p+p$ collisions. This modification stems from the energy loss of hard-scattered partons traversing the Quark Gluon Plasma (QGP) before fragmenting into jets. Examining the jet modification allows us to study how the jet energy energy diffuses as the hard-scattered partons traverse the QGP, as well as the possible modification of the fragmentation function, $D(z)$, due to energy loss. PHENIX has made new measurements using two particle correlations to study jet modification. By spatially correlating all charged hadrons in an event to a high $p_T$ trigger, one can observe modifications to the yield and angular distribution of the away-side jets peaking opposite the trigger particle direction. $I_{AA}$, the ratio of the away-side integrated yield in $A+A$ to that in $p+p$, is extracted from two-particle correlations. For direct photon triggered two-particle correlations in particular, $I_{AA}$ provides insight into fragmentation function modification as the integrated conditional yields $Y_{AA}$ and $Y_{pp}$ are related to the fragmentation functions, ${D_{AA}}(z)$ and ${D_{pp}}(z)$, i.e.: $I_{AA} = \frac{Y_{AA}}{Y_{pp}}\approx\frac{{D_{AA}(z)}}{{D_{pp}(z)}}$.
     This poster will show the latest two-particle correlation results by PHENIX in $Au+Au$ collisions at $\sqrt{s_{NN}}=200$~GeV collisions, utilizing both the $\pi^0$ and the direct photon as the trigger species. To quantify modification of the recoil jets opposite the trigger particle, measurements of the away-side $I_{AA}$ and Gaussian jet width $\sigma$ will be shown as a function of the associate particle $p_T$. Additionally, a new PHENIX result, the $I_{AA}$ as a function of the separation angle between the trigger and associate particle, $\Delta \phi$, probes modification to the fragmentation function spatially and in $p_T$.

Contribution type Poster
Track Jets and High Momentum Hadrons
Collaboration (if applicable) PHENIX

Primary author

Anthony Hodges (Georgia State University)

Presentation materials