Medium information from Harmonic Flow and Jet Quenching in Relativistic Heavy Ion Collisions, S. Pal, Tata Institute of Fundamental Research, Mumbai, India − Heavy ion collisions at the Relativistic Heavy Ion Collider (RHIC) and recently at the Large Hadron Collider (LHC) have revealed a new state of matter comprising of strongly coupled quark-gluon plasma.  Primary evidence of this is provided by the observed suppression of high transverse momenta hadron spectra in central heavy ion collisions relative to both peripheral and nucleon-nucleon collision.  The recent anisotropic flow and suppression data for charged hadrons up to high p_T (and small x) at LHC/CERN has provided interesting opportunities to constrain both the initial state and the final-state partonic medium formed in the collisions.  We have developed a multiphase transport (AMPT) model whose initial conditions are obtained from the recently updated HIJING 2.0 model that allows to study collisions over a wide energy range.  Hadron production within the updated AMPT model at RHIC/BNL and in particular at LHC/CERN are studied.  The centrality dependence of charged hadron multiplicity dN_ch/dy at midrapidity was found quite sensitive to the largely uncertain gluon shadowing parameter s_g that determines the nuclear modification of the gluon distribution.  We find final-state parton scatterings reduce considerably hadron yield at midrapidity and enforces a smaller gluon shadowing so as to be consistent with dN_ch/dy data at LHC.  With the parton shadowing so constrained, we report on the AMPT prediction of anisotropic flow coefficients: the elliptic v₂, triangular v₃, and quadrangular v₄, and mixed harmonics which are in reasonable agreement with that measured at RHIC and LHC energies. Further, charged hadron and neutral pion production over a large p_T are investigated in AMPT.  Relative to nucleon-nucleon collisions, the particle yield in central heavy ion collisions is suppressed due to parton energy loss which, in turn, was found quite sensitive to parton scattering cross section.  While the model calculations of the magnitude and pattern of suppression are consistent with measurements in Au+Au collisions at 0.2 TeV at RHIC, the suppression is however distinctly overpredicted in Pb+Pb collisions at the LHC energy of 2.76 TeV.  The implications and new challenges to understand the unexpectedly transparent strongly coupled QGP formed at LHC will be presented.