Determination of the chemical potential and the energy of the \nu=1/2 FQHE system for low temperatures

We consider the energy density of a spin polarized $\nu=1/2$ system for low temperatures. We show that due to the elimination of the magnetic field and the field of the positive background charge in the calculation of the grand canonical potential of Chern-Simons systems through a mean field formalism one gets corrections to the well known equations which determine the chemical potential and the energy from the grand canonical potential. We use these corrected equations to calculate the chemical potential and the energy of the $\nu=1/2$ system at low temperatures in two different approximations.Comment: 9 Revtex pages, 1 eps figure, using style files pst-feyn.sty, pst-key.sty, typos corrected, one subsection adde

The asymptotic behaviour of the exact and approximative ν=1/2\nu=1/2 Chern-Simons Green's functions

We consider the asymptotic behaviour of the Chern-Simons Green's function of the $\nu=1/\tilde{\phi}$ system for an infinite area in position-time representation. We calculate explicitly the asymptotic form of the Green's function of the interaction free Chern-Simons system for small times. The calculated Green's function vanishes exponentially with the logarithm of the area. Furthermore, we discuss the form of the divergence for all $\tau$ and also for the Coulomb interacting Chern-Simons system. We compare the asymptotics of the exact Chern-Simons Green's function with the asymptotics of the Green's function in the Hartree-Fock as well as the random-phase approximation (RPA). The asymptotics of Hartree-Fock the Green's function corresponds well with the exact Green's function. In the case of the RPA Green's function we do not get the correct asymptotics. At last, we calculate the self consistent Hartree-Fock Green's function.Comment: 12 Revtex pages, 1 eps figure, using style files pst-feyn.sty, pst-key.sty, typos correcte

Jets and Photons in ALICE

ALICE measured transverse momentum spectra of pi0 and eta mesons via the two photon decay in pp collisions at sqrt(s)=0.9, 2.76 and 7 TeV and Pb-Pb collisions at sqrt(sNN)=2.76 TeV. NLO pQCD calculations agree with p-p measurements at 0.9 TeV, but overestimate the data at 2.76 and 7 TeV. The nuclear modification factor for neutral pions shows a strong suppression of high-pt particle production in central Pb-Pb collisions. Raw spectra of charged particle jets have been measured in Pb-Pb collisions. Detailed studies of background fluctuations have been performed and will allow us to unfold the spectra even for low momentum cut offs, giving access to soft fragmentation products in quenched jets.Comment: EPIC@LHC - International Workshop on Early Physics with heavy-Ion Collisions at LH

Hard physics in STAR

The hot and dense matter created in high-energy nuclear collisions is believed to undergo a transition into a deconfined phase where partonic degrees of freedom determine the dynamics of the medium. High-p⊥ partons, that are produced in the initial collisions between nucleons of the incoming nuclei, lose energy as they propagate through the medium. This effect, called jetquenching, is observed in high-p⊥ particle spectra, in azimuthal correlations with the reaction plane (elliptic flow) and jet-like two-particle correlations. STAR consists of tracking detectors and electromagnetic calorimetry with large and azimuthally symmetric acceptance and is exceptionally well suited for single particle detection and correlation studies at high p⊥. In the last five years, it has collected a large dataset including Au+Au and Cu+Cu collisions at different energies and reference data from p+p and d+Au collisions. We present particle spectra and two-particle correlations at high-p⊥, and relate these measurements to the properties of the medium