Database

Creator

Date

Thumbnail

Search results

36 records were found.

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.
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.
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.
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.
We try to understand recent data on proton-proton and deuteron-gold collisions at RHIC, employing a modified parton model approach.
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.
Comment: Invited talk, given at the XXth Winter Workshop on Nuclear Dynamics, Trelawny Beach, Jamaica, March 2004
Want to know more?If you want to know more about this cutting edge product, or schedule a demonstration on your own organisation, please feel free to contact us or read the available documentation at http://www.keep.pt/produtos/retrievo/?lang=en