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36 records were found.

## On QGP Formation in pp Collisions at 7 TeV

The possibility of QGP formation in central pp collisions at ultra-high collision energy is discussed. Centrality-dependent $\pt$-spectra and (pseudo)rapidity spectra of thermal photons (charged hadrons) from pp collisions at 7 TeV are presented (addressed). Minimal-bias $\pt$-spectrum of direct photons and charged hadrons is compared under the framework with and without hydrodynamical evolution process.

## Micro-canonical pentaquark production in $e^+e^−$ and pp collisions

The existence of pentaquarks became questionable, because the Θ+ peak is observed in some p+p collisions, but not in e+e− annihilations. People think initial baryon number is necessary to produce pentaquarks. In this paper, we estimate and compare the production of Θ+(1540) and Ξ−−(1860) in e+e− and pp collisions at different energies using Fermi statistical model as originally proposed in its microcanonical form. We find that both Θ+(1540) and Ξ−−(1860) yield more in e+e− at LEP energies than in pp collisions at SPS and RHIC energies, if pentaquarks do exist. Initial baryon number is not necessary for pentaquark production.

## Microcanonical pentaquark production in electron-positron annihilations

The existence of pentaquarks, namely baryonic states made up of four quarks and one antiquark, became questionable, because the candidates, i.e. the $\Theta^+$ peak, are seen in certain reactions, i.e. p+p collisions, but not in others, i.e. $\ee$ annihilations. In this paper, we calculate the production of $\Theta ^{+}(1540)$ and $\Xi (1860)$ in $\ee$ annihilations at 91.2 GeV with a microcanonical approach. A rather high production of pentaquark states is obtained. It is comparable with that from pp collisions at RHIC energy, and higher than the yield from pp collisions at SPS energy. If pentaquark states exist, the production is highly possible from high energy collisions, even without initial baryons.

## Parton Ladder Splitting and the Rapidity Dependence of Transverse Momentum Spectra in Deuteron-Gold Collisions at RHIC

We present a phenomenological approach (EPOS), based on the parton model, but going much beyond, and try to understand proton-proton and deuteron-gold collisions, in particular the transverse momentum results from all the four RHIC experiments. It turns out that elastic and inelastic parton ladder splitting is the key issue. Elastic splitting is in fact related to screening and saturation, but much more important is the inelastic contribution, being crucial to understand the data. We investigate in detail the rapidity dependence of nuclear effects, which is actually relatively weak in the model, in perfect agreement with the data, if the latter ones are interpreted correctly.

## Proton-proton and deuteron-gold collisions at RHIC

We try to understand recent data on proton-proton and deuteron-gold collisions at RHIC, employing a modified parton model approach.

## Production of Pentaquark States in pp Collisions within the Microcanonical Ensemble

The microcanonical statistical approach is applied to study the production of pentaquark states in pp collisions. We predict the average multiplicity and average transverse momentum of Theta^{+}(1540) and Xi(1860) and their antiparticles at different energies.

## Comparison of Microcanonical and Canonical Hadronization

Comment: 14 pages, 7 figures

## Proton-proton and deuteron-gold collisions at RHIC

Comment: Invited talk, given at the XXth Winter Workshop on Nuclear Dynamics, Trelawny Beach, Jamaica, March 2004