Session 3WBB: Future of Hot and Cold QCD Physics at High-energy Colliders and their Synergies II

Current Understanding and Open Questions in Hot and Dense QCD Theory

This talk aims to discuss the current knowledge and open queries in hot and dense Quantum Chromodynamics (QCD). Understanding QCD under extreme conditions is essential to reveal the early universe and the nature of dense cosmic objects like neutron stars. We will delve into the QCD phase diagram, addressing the interplay between confinement and deconfinement phases, as well as the phenomena of Quark-Gluon Plasma (QGP) and color superconductivity. We will introduce approaches to QCD phase diagrams using generalized global symmetries and discuss the current understanding of quark-hadron continuity at finite density. A significant theoretical challenge is understanding high-density and nonequilibrium QCD. This is largely due to the difficulties in analyzing Lattice QCD using Monte Carlo simulations, stemming from the so-called sign problem. We will present various innovative methods to overcome this problem, such as tensor network methods and quantum computation.   

Future prospects of hot and cold QCD physics at RHIC and LHC

Within a decade, we are going to enter a new era on QCD studies. In USA, the new accelerator, the Electron-Ion Collider (EIC) will be built to study the internal structure of nucleon and nucleus more precisely than ever, and at CERN, new detector upgrades are planed at LHC, for instance, Forward Calorimeter (FoCal) and Inner Tracking System 3 (ITS3) for LHC Run-4, and ALICE3 for Run-5 and beyond. The sPHENIX program is just started at RHIC. There is a strong synergy between LHC and RHIC on both hot QCD and cold QCD. For the hot QCD, sPHENIX will provide more precise measurements on properties of quark-gluon plasma (QGP) at RHIC energies, so that by comparing the measurements at LHC, we could obtain a temperature dependences of QGP properties. And by combining the data by FoCal at LHC and EIC, we could explore a wide kinematic coverage of x-Q space, in order to see a non-linear QCD evolution, and determine a nature of gluon saturation for the first time. In this talk, we will review the current status of hot and cold QCD physics at RHIC and LHC. And the future prospects of upgrades at LHC with synergy of EIC measurements with regards to the new understanding of QCD will be reported.   

From Hadrons to Electrons - The Road from RHIC to the EIC

The Relativistic Heavy-Ion Collider (RHIC), located at Brookhaven National Laboratory, has been at the forefront of the exploration of the fundamental structure of strongly interacting matter for over two decades.  Quantum Chromodynamics (QCD), the theory of the strong nuclear force, has many interesting, emergent properties.  RHIC continues to make important discoveries in both Hot and Cold QCD, from the quark gluon plasma (QGP) formed in collisions of heavy ions, with remarkably small viscosity, to the spin structure of the proton.  Small systems, which form QCD matter with signatures of collective behavior similar to those observed in a QGP, have added to the complexity of the QCD story.  RHIC has been extremely versatile and can collide many different species and is the only collider with polarized proton beams.  The Electron-Ion Collider (EIC) will be an innovative, large-scale facility to be constructed at Brookhaven, utilizing key components of the RHIC complex. The EIC will study nucleons and nuclei with the most powerful electron microscope ever built, in order to address some of the most fundamental questions such as the origin of nucleon mass and spin, and the emergent properties of a dense system of gluons.  I will discuss key discoveries that have been made at RHIC, the critical measurements that need to be made in the last years of operations to finish the science mission, and how the scientific program in QCD will be transformed with the unprecedented reach and precision available at the EIC.