Frontiers of Nuclear Physics A Personal Outlook Huan Zhong Huang Department of Physics and Astronomy University of California, Los Angeles Department of Engineering Physics Tsinghua University

With the right tools Nuclear Physics is poised to make significant discoveries that will also impact other fields Nuclear Physics is the study of: Nucleons and atomic nuclei as complex, many body system of quarks or neutrons and protons Bound together by fundamental forces (Quantum Chromo-Dynamics (QCD), nucleon-nucleon force (NN)) Deep connection with evolution of the universe - production of the chemical elements – stars, supernovae, etc. RHIC CEBAF RIA protons electrons Tests of Standard Model Underground Experiments Cold Neutron Experiments Rare Isotope Accelerator (RIA)  CEBAF 12 GeV Upgrade  RHIC upgrade (RHIC II) 

Topics 1)RHIC Upgrade 2)JLab 12 GeV Upgrade 3)Rare Isotope Accelerator 4)Underground Laboratory 5)Electron-Ion Collider

STAR Relativistic Heavy Ion Collider --- RHIC Au+Au 200 GeV N-N CM energy Polarized p+p up to 500 GeV CM energy

Quark-Hadron Phase Transition

Hadronization of Bulk Partonic Matter 1) At the moment of hadronization in nucleus-nucleus collisions at RHIC the dominant degrees of freedom is related to number of constituent quarks. 2) These ‘constituent quarks’ exhibit an angular anisotropy resulting from collective interactions. 3) Hadrons seem to be formed from coalescence or recombination of the ‘constituent quarks’, and the hadron properties are determined by the sum of ‘constituent quarks’. Deconfined Quark Degree of Freedom

Constituent Quark Scaling STAR PHENIX Baryon Meson Constituent (n) Quark Scaling -- Meson n=2 and Baryon n=3 grouping Saturation of v 2 at Intermediate p T

Partonic v 2 and Surface Emission PRL 92 (2004) ; PRL 91 (2003) At hadron formation time there is a collective v 2 among constituent quarks Recombination/coalescence provides a hadronization scheme (not necessarily related to partonic matter, works for d+Au) Possible geometrical nature of v 2 saturation – surface emission

Conditions at T c Empirically, Partonic matter evolves such that at the hadronization, the dominant degrees of freedom are in ‘constituent quarks’/quasi-hadrons. The formation mechanism could be coalescence or recombination of these quarks. Gluon degrees of freedom are not manifested at hadronization, though at initial stage of the heavy ion collision, gluons must dominate.

Lattice QCD LQCD, Spectral functions of hadrons (J/psi and light hadrons) survive near T C or somewhat above T C. Strong correlations persist up to high temperature above T C ! LQCD e.g. S. Datta et al, hep-lat/ J/  and  C may survive up to 2.25 T C ! Our data indicate that at T=T C even light hadrons are in quasi-hadron state (strongly interacting constituent quark state) !

Phase Transition ? The Initial State from the Collision must be dominated by gluons (Temperature?)  Parton Evolutions (?)  At the Hadronization Stage the dominate degrees of freedom are constituent quarks (or quasi-hadrons) (Empirical + LQCD) What is the parton evolution dynamics?? Empirically the dense matter with collective motions of constituent quark degrees of freedom must be preceded with a deconfined partonic matter, BUT we do not have any experimental indication that this is a phase transition !

RHIC Physics in + Years 1)Heavy Quark Production -- Yield and pT distribution (Energy Loss) -- Parton Collectivity (Elliptic Flow) 2) Thermal Photon Radiation 3) QCD Photons (gamma-jet and QGP Brem.) 4) Chiral Symmetry and low mass di-leptons 5) Exotic Particle Searches 6) Search for QCD Critical Point – Low Energy Scan

STAR – Exciting Physics Program A full TOF and Heavy Flavor Tracker upgrade will greatly enhance STAR’s capability !! RHIC – Exotic Particle Factory Heavy Flavor Tracker Using Active Pixel Sensor two layers of thin silicon detector 1.5 cm and 4 cm radius Charmed Exotics?! Full Barrel TOF Using MRPC

Hadron Blind Detector Gas Box for CF4 CsI-doped Triple GEMs Preamps

Pixel barrel m x 425  m) Strip barrels(80  m x 3 cm) Endcap Pads 1.2<|  |< 2.4 |  |< 1.2 Silicon Vertex Tracker (VTX)

RHIC Beyond +5 Years Hadrons with internal structure beyond existing QCD qqq and q-qbar framework !! pp pA AA pp pA AA Exotic RHIC – Dedicated QCD Machine&Beyond (spin) (CGC,EMC) (Deconfinement Phase Transition)

Jefferson Lab (JLab)

Structure of the Nucleon Nucleon anomalous magnetic moment (Stern, Nobel Prize 1943) Electromagnetic form factor from electron scattering (Hofstadter, Nobel Prize 1961) Deep-in-elastic scattering, quark underlying structure of the nucleon (Freedman, Kendell, Feldman, Nobel Prize 1990)

JLab 12 GeV Upgrade Scientific Goals: 1) Quark structure of the proton 2) Gluons in the proton 3) Nature of Confinement 4) Exotic Particles Glueball proton

Underground Laboratory Physics Topics: 1) Solar Neutrino/Atmosphere Neutrino 2) Double beta Decay 3) Dark Matter

Solar Neutrino Energy Spectrum

Two Generation Model 1.24 (P e  minimum)

combined analysis SNO and KamLand Best fit:  m 2 =7.1 x eV 2 tan 2  = 0.41

eRHIC as an electron-ion collider

eRHIC Inevitable ?! But When? RHIC II – Machine Upgrade -- Tandem -- Electron Cooling Electron – LINAC 10 GeV Natural Physics Direction from RHIC/JLAB 20 Years ?

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