Parton recombination at all pTp_T

Hadron production at all $p_T$ in heavy-ion collisions in the framework of parton recombination is reviewed. It is shown that the recombination of thermal and shower partons dominates the hadron spectra in the intermediate $p_T$ region. In $d+Au$ collisions, the physics of particle production at any $\eta$ is basically the same as at $\eta=0$. The Cronin effect is described as a result of the final-state instead of the initial-state interaction. The suppression of $R_{CP}$ at high $\eta$ is due to the reduction of the soft parton density on the deuteron side, thus resulting in less pions produced by recombination, an explanation that requires no new physics. In $Au+Au$ collisions large $p/\pi$ ratio is obtained because the thermal partons can contribute to the formation of proton more than they do to the pion.Comment: 12 pages + 5 figures. Invited talk at Hard Probes 200

Comparison of Nuclear Suppression Effects on Meson Production at High p_T and p_L

The medium effect on the pion distribution at high $p_T$ in $AA$ collisions is compared to that of the pion distribution at high $p_L$ in $pA$ collisions. Both the suppression of the spectra and the energy losses of the measured pions are studied. Although the medium effect on $p_T$ is larger than on $p_L$, the difference is found surprisingly to be not as big as one would naively expect.Comment: 8 RevTex pages with 5 figure

Correlations at intermediate pTp_T

Correlations among hadrons in jets produced in heavy-ion collisions are discussed in the framework of the recombination model. The basic correlation at the parton level is among the shower partons arising from kinematical constraint. The resultant correlation between hadrons at intermediate $p_T$ is amazingly rich in characteristics.Comment: 10 pages including 12 figures. Talk presented at the MIT Workshop on Correlations and Fluctuations in Relativistic Nuclear Collisions, April 200

Fragmentation or Recombination at High p_T?

All hadronization processes, including fragmentation, are shown to proceed through recombination. The shower partons in a jet turn out to play an important role in describing the p_T spectra of hadrons produced in heavy-ion collisions. Due to the recombination of the shower partons with the soft thermal partons, the structure of jets produced in AA collisions is not the same as that of jets produced in pp collisions.Comment: Talk given at Quark Matter 200

Resolutions of Several Puzzles at Intermediate pTp_T and Recent Developments in Correlation

Some of the puzzles on hadron production at intermediate $p_T$ found at RHIC are explained as natural consequences of parton recombination. In that framework for hadronization the correlation among hadrons produced in jets can be calculated. Some new results on both near-side and away-side jet structures are presented.Comment: 5 pages in LaTeX , 0 figures. Talk given at Quark Matter 200

Quark-hadron phase transition with surface fluctuation

The effect of surface fluctuation on the observables of quark-hadron phase transition is studied. The Ginzburg-Landau formalism is extended by the inclusion of an extra term in the free energy that depends on the vertical displacements from a flat surface. The probability that a bin has a particular net displacement is determined by lattice simulation, where the physics input is color confinement. The surface fluctuation from bin to bin is related to multiplicity fluctuation, which in turn is measured by the factorial moments. It is found that both the F-scaling behavior and the scaling exponent are essentially unaffected by the inclusion of surface fluctuation.Comment: 9 pages, LaTex, 7 figures in a single postscript file, submitted to Phys. Rev.