Speaker
Description
A search for medium-induced jet transverse momentum broadening is performed with isolated photon-tagged jet events in proton-proton (pp) and lead-lead (PbPb) collisions at nucleon-nucleon center-of-mass energy $5.02$ TeV. The difference between jet axes as determined via energy-weight and winner-take-all clustering schemes, also known as the decorrelation of jet axes and denoted $\Delta j$, is measured for the first time in photon-tagged jet events. This observable is sensitive to both multiple scattering and large-angle scattering effects in the QGP. The pp and PbPb data samples were recorded with the CMS detector at the LHC and correspond to integrated luminosities of 1.69 nb$^{-1}$ and 302 pb$^{-1}$ respectively. Events are required to have a leading isolated photon with $60 < p_{T}^{\gamma} < 200$ GeV, which is correlated with anti-\kt $R = 0.3$ jets with $30 < p_{T}^{jet} < 100$ GeV opposite in azimuthal angle. Event selection on colorless high-pT bosons reduces the medium-induced survivor’s bias present in inclusive jet measurements of $\Delta j$. The PbPb results are reported as a function of collision centrality and compared to pp reference data. Jets with $p_{T}^{jet} < 60$ GeV have consistent shape in PbPb relative to pp. However, jets with $p_{T}^{jet} > 60$ GeV in central PbPb show signs of narrowing relative to pp. The results are compared to the Jewel and Pyquen theoretical models, which include different methods of energy loss.
| Category | Experiment |
|---|---|
| Collaboration | CMS |
