Bulletin of the American Physical Society
Fall 2022 Meeting of the APS Division of Nuclear Physics
Volume 67, Number 17
Thursday–Sunday, October 27–30, 2022; Time Zone: Central Daylight Time, USA; New Orleans, Louisiana
Session KF: Jets in Heavy-ion Collisions II |
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Chair: Raghav Kunnawalkam Elayavalli Room: Hyatt Regency Hotel Celestin F |
Saturday, October 29, 2022 10:30AM - 10:42AM |
KF.00001: Constraining jet energy-loss distributions in heavy-ion collisions. Ron A Soltz The study of jet quenching in heavy-ion collisions is a topic of active experimental and theoretical investigation. We apply Bayesian techniques to test simple parameterizations of jet energy loss in Pb+Pb collisions measured at the LHC. Jet energy loss observables such as jet RAA and jet asymmetry are used to constrain the mean and rms-width of the energy loss distributions. These parameterizations are also used to study the explore assumptions regarding various forms of correlated errors within each observable and experiment. Impacts for future theoretical models and presentation of experimental data are discussed. |
Saturday, October 29, 2022 10:42AM - 10:54AM |
KF.00002: Isolated photon cross sections in pp and p-Pb at 5.02 TeV with ALICE Dhruv Dixit Prompt photons, produced via QCD Compton scattering or quark and anti-quark annihilation at leading order, are unique probes to study QCD processes since they do not interact strongly and therefore allow to control the dynamics of the initial hard parton scattering. Isolated photon production in pp collisions is one of the most clear tests of perturbative QCD processes and parton distribution functions. Photon measurement in p-A collisions provides the opportunity to measure possible modifications of the nucleon structure function in nuclei. ALICE has measured isolated photons at low pT, thus extending previous measurements down to small x. In this talk, the cross section of isolated photons for the range 12 GeV/c < pT < 60 GeV/c is presented in pp and p-Pb collisions at 5.02 TeV . |
Saturday, October 29, 2022 10:54AM - 11:06AM |
KF.00003: Measurements of jet and soft activity in √sNN = 200 GeV p+Au collisions at STAR Veronica Verkest Proton-ion collisions at the LHC and RHIC have yielded unexpected trends, notably in measurements of jet nuclear modification factor as a function of event activity (EA). Recent preliminary measurements from STAR in p+Au collisions at √sNN = 200 GeV demonstrate inherent correlations between high-Q2 parton scatterings and EA measured at backward (Au going) rapidities or underlying event (UE) at mid-rapidity. The measurements at STAR disfavor jet quenching as an explanation for the suppression of jet yield observed in high-EA collisions. This leads to an opportunity to probe the early stages of the proton-ion collisions. In this talk, we show correlations of backward-rapidity EA with mid-rapidity UE, as well as measurements of EA-dependent modifications to charged hadron spectra and jet production. In particular, we present measurements of the UE for various EA selections and discuss its kinematic dependence on jet pseudorapidity and transverse momentum (pT) as a means of examining the correlation between initial hard scatterings and soft processes. We also investigate the EA dependence of high-pT hadron and jet properties—including fully corrected ungroomed and SoftDrop groomed jet substructure observables—to study the impact of initial and final state effects. |
Saturday, October 29, 2022 11:06AM - 11:18AM |
KF.00004: Exploring the hadrochemistry of jet energy loss in ALICE Sierra L Weyhmiller Energetic partons lose energy in the quark-gluon plasma (QGP) medium and then fragment into showers of particles called jets. It has been observed that this lost energy is mainly transferred to low-energy particles at large angles with respect to the jet axis. However, the particle composition of this transferred jet energy loss is not yet well understood. It has been predicted that the jet hadrochemical composition will be modified due to the QGP medium. |
Saturday, October 29, 2022 11:18AM - 11:30AM |
KF.00005: Suppression of high pT Pi0 relative to prompt photon in central d+Au collision at 200GeV. Niveditha Ramasubramanian, Niveditha Ramasubramanian The initial motivation to study d+Au collisions was to use it as a control experiment to decouple the effects of cold nuclear matter effects in the nuclear modification factors (RAA) obtained from heavy ion collisions like Au+Au. Since the year 2013, there has been a growing evidence of the possibility of formation of Quark Gluon Plasma (QGP) in small systems. Suppression in the nuclear modification factor RAA of Pi0 and jets is observed in the central d+Au collisions, which could be attributed to formation of QGP droplets but, along with this, the results also indicate a counter-intuitive enhancement of RAA in peripheral events. |
Saturday, October 29, 2022 11:30AM - 11:42AM |
KF.00006: D0-meson tagged jet-substructure measurement in pp collisions at $\sqrt{s} =$ 5.02 TeV with ALICE Preeti Dhankher Measurements of heavy-flavor hadron production play an important role in test of pQCD calculations and represent a critical component of studies of quark-gluon plasma (QGP) created in heavy-ion collisions. A more complete picture of the kinematics of these partons can be captured using heavy-flavour tagged jet. One of the interesting class of jet substructure observable are jet angularities which characterize the angular and momentum distribution of particles within jets. |
Saturday, October 29, 2022 11:42AM - 11:54AM |
KF.00007: Measurements of the Collision Energy Dependence of the Polarized $\gamma \gamma \rightarrow e^{+} e^{-}$ Process in Peripheral Au+Au Collisions with the STAR Detector Xiaofeng Wang In ultra-relativistic heavy-ion collisions, strong electromagnetic fields arising from the Lorentz-contracted, highly charged nuclei can be approximated as a large flux of high-energy quasi-real photons. |
Saturday, October 29, 2022 11:54AM - 12:06PM |
KF.00008: Unfolding jet substructure observables with a machine learning method at √s = 200 GeV in pp collisions in STAR Youqi Song Jets are collimated sprays of final-state particles produced from initial hard partonic (quark/gluon) scatterings in particle collisions. Since jets are multi-scale objects that connect asymptotically free partons to confined hadrons, jet substructure measurements in vacuum can provide insight into the parton evolution and the ensuing non-perturbative processes. Jet substructure observables are usually unfolded to correct for detector effects with a binned, one- or two-dimensional Bayesian method. Potentially, it is more desirable to unfold in higher dimensions which can account for the possible correlation in the multi-dimensional observable phase space while simultaneously correcting it. |
Saturday, October 29, 2022 12:06PM - 12:18PM |
KF.00009: Quantum simulation of jet quenching in nuclear environments Xiaojun Yao Jet quenching has been used as a probe of the quark-gluon plasma in heavy ion collisions for decades. Traditional approaches of understanding parton in-medium dynamics are based on a perturbative description of parton splitting with medium modifications and have difficulties in analyzing a quantum interference effect called the Landau-Pomeranchuk-Migdal (LPM) effect, for processes with more than two splittings. In this talk, I will show a framework for quantum simulation of jet in-medium evolution. The framework is based on the light-front Hamiltonian dynamics of QCD which contains a kinetic evolution term, transverse momentum exchange between partons and the medium and parton splitting/recombination. I will argue that very likely we can efficiently simulate the jet in-medium evolution on a quantum computer. The framework automatically keeps track of quantum interference and thus can be applied to study the LPM effect with more than two splittings, no matter whether the medium is static or expanding, thin or thick, hot or cold. Some quantum simulation results of a toy model will also be presented, where the LPM effect that suppresses the radiation probability is observed. |
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