Imaging the longitudinal structure of the QGP using different shaped nuclei

by Prof. Jiangyong Jia (SBU & BNL)

Tuesday 27 Oct 2026, 10:30 → 11:30 Asia/Shanghai

B105 (CHEP)

How energy is deposited along the beam direction, and how it fluctuates, is the least constrained part of the initial state of heavy-ion collisions. Accessing this structure is notoriously difficult because of short-range nonflow correlations, and the traditional observable r2(η) provides only incomplete and biased information about longitudinal decorrelation. Isobar-like collisions have been used to image the shapes of atomic nuclei; here we introduce a strategy that turns nuclear shape into a controlled instrument for the longitudinal structure of the QGP. A change in nuclear shape perturbs the longitudinal geometry while leaving the nonflow background and the final-state response essentially unchanged. In AMPT simulations of central U+U and Au+Au collisions we extract the full two-particle rapidity correlation map， which reveals a nonlinear, nonadditive loss of correlation and a previously unquantified acceptance-dependent bias in standard flow measurements, about 16% for references four units from mid-rapidity. This idea can be directly applied to understand longitudinal fluctuations in ellipticity, triangularity and transverse size using existing U+U/Au+Au, Ru+Ru/Zr+Zr and O+O/Ne+Ne data. In small systems it can determine whether this bias explains the long-standing flow puzzle. Nuclear structure thus becomes a precision instrument for three-dimensional imaging of the QGP initial conditions.

Bio:
Jiangyong Jia is a professor in Stony Brook University (SBU) and physicist in Brookhaven National Laboratory (BNL). He is member of RHIC-STAR and LHC-ATLAS, and previously the RHIC-PHENIX experiments, with broad interests in high energy nuclear physics and particle physics. However, his main expertise is in the area of collective flow, hydrodynamics and particle correlations from small to large collision systems. He received his B.S. degree from USTC in 1997, Ph.D. from SBU in 2003, worked as a postdoc in Columbia University, before joining the faculty at SBU and BNL in 2006.