Hadron Ion Tea (HIT) Seminar Series
[formerly the Heavy Ion Tea Seminars]
Nuclear Science Division
Lawrence Berkeley National Laboratory
HIT seminars are on Tuesdays and Thursdays at 3:30pm Pacific Time (unless otherwise noted)
Organizers: Shujie Li, Dimitra Pefkou, Nu Xu, & Wenbin Zhao
Previous seminars can be viewed on our HIT Youtube Channel
Upcoming seminars
Welcome to our Hadron-Ion Tea Seminar Series in 2024! All talks are available on zoom, some are in-person as well - we hope you join us!
Tuesday, April 30th, 3:30PM (in-person and on zoom)
Dr. Daniel Hackett (Fermilab)
Host: Dimitra Pefkou
"Machine-learned flows for QCD"
Abstract coming soon!
Tuesday, May 7th, 3:30PM (in-person and on zoom)
Zhiquan Sun (MIT)
Host: Dimitra Pefkou
Title and abstract coming soon!
Friday, May 10th, 10am (on zoom)
Jaime Norman (University of Liverpool)
Host: Peter Jacobs
Probing jet energy redistribution and broadening in heavy-ion collisions with ALICE at the LHC
Heavy-ion collisions at the LHC generate the hottest form of matter that can be created in a lab - 100 thousand times hotter than the centre of the sun - where hadronic matter exists in a deconfined state of quarks and gluons, the ‘Quark-Gluon Plasma’ (QGP). Jets - collimated sprays of hadrons originating from a high-momentum quark or gluon - are generated in heavy-ion collisions, and their interactions with the QGP provide unique probes of its properties. A key question in the study of the QGP is whether its short-distance structure can be resolved and studied, and a ‘scattering experiment’ involving jets, analogous to Rutherford’s experiment which determined the structure of the atom, offers one of the most promising ways to achieve this. Such effects are expected to be most prominent at low jet transverse momentum ($p_\mathrm{T}$), which is where jet measurements are also sensitive to wake effects due to response of the QGP itself to the jet-medium energy transfer. Measurements that are differential in jet $p_\mathrm{T}$, jet radius $R$, and acoplanarity (deflection angle) may be able to disentangle these various mechanisms.
This talk presents a new measurement of charged-particle jets recoiling from a trigger hadron in proton-proton and central lead-lead collisions by ALICE - the LHC experiment dedicated to studying heavy-ion collisions. The measurement is performed using a background-subtraction technique which provides a precise data-driven subtraction of the large uncorrelated background contaminating the measurement, uniquely enabling the measurement of jet production and acoplanarity over a wide phase space, including the low jet $p_\mathrm{T}$ region for large $R$.
Tuesday, May 14th, 3:30PM (in-person and on zoom)
Dr. Anar Rustamov (GSI)
Host: Nu Xu
"Decoding the QCD Phase Transition via Cumulants of Particle Multiplicity Distributions in High-Energy Nuclear Collisions"
QCD, the theory of strong interactions, predicts that at sufficiently high temperatures and/or densities, chiral symmetry is restored, and confinement is lifted. Consequently, standard matter, consisting of hadrons, undergoes a phase transition into a state of the quark gluon plasma, where quarks and gluons can roam freely. The phase structure of QCD matter can be decoded by investigating properties of the system, created in head-on collisions of heavy nuclei. In this presentation this goal will be addressed by investigating the response of the system to external perturbations encoded in fluctuations of baryon number from event-to-event. Specifically, several novel approaches will be presented to quantify: (i) Correlations between baryon-antibaryon, baryon-baryon, and antibaryon-antibaryon pairs. (ii) To account for unavoidable contributions from volume (or participant) fluctuations to experimentally measured cumulants of (net-)proton number distributions. The proposed methods will be used to discuss fluctuation measurements in a broad range of center-of-mass energies ranging from several TeV down to several GeV, such as those measured in Pb-Pb and Au-Au collisions by the ALICE, STAR and HADES experiments.
Tuesday, May 28th, 3:30PM (in-person and on zoom)
Meijian Li (Santiago de Compostela Univeersity)
Host: Xin-Nian Wang
"Scattering and gluon emission of a dressed quark in colored field"
Following the non-perturbative light-front Hamiltonian formalism developed in the preceding works [Phys. Rev. D 104, 056014 (2021), Phys. Rev. D 108, 036016 (2023)], we investigate the scattering and gluon emission of dressed quark states inside a SU(3) colored background field. We consider the scenario in deep inelastic scattering and in heavy ion collisions, where the quark originates from far outside the background field and is described by the light-front wavefunction of the QCD eigenstate in the |q>+|qg> Fock space. We perform numerical simulations of the real-time quantum state evolution of an initially dressed quark state at various energy and medium configurations. With the obtained light-front wavefunction of the evolved state, we extract the quark jet transverse momentum distribution, the cross section, and the gluon emission rate. This investigation provides a novel systematic description of the quark scattering process inside colored medium using a non-perturbative formalism.
Tuesday, June 4th, 3:30PM (on zoom)
Chun Shen (Wayne State University)
Host: Wenbin Zhao
Title and abstract coming soon!