1,044 research outputs found
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.Comment: Invited talk, given at the XXth Winter Workshop on Nuclear Dynamics,
Trelawny Beach, Jamaica, March 200
A New String Model: NEXUS 3
After discussing conceptual problems with the conventional string model, we
present a new approach, based on a theoretically consistent multiple scattering
formalism.
First results for proton-proton scattering at 158 GeV are discussed.Comment: invited talk given at the 9th Winter Workshop on Nuclear Dynamics,
Breckenridge, Colorado, February 9 - 14, 200
Evidence for flow in pPb collisions at 5 TeV from v2 mass splitting
We show that a fluid dynamical scenario describes quantitatively the observed
mass splitting of the elliptical flow coefficients v2 for pions, kaons, and
protons. This provides a strong argument in favor of the existence of a fluid
dynamical expansion in pPb collisions at 5TeV
Jets, Bulk Matter, and their Interaction in Heavy Ion Collisions at Several TeV
We discuss a theoretical scheme that accounts for bulk matter, jets, and the
interaction between the two. The aim is a complete description of particle
production at all transverse momentum () scales. In this picture, the
hard initial scatterings result in mainly longitudinal flux tubes, with
transversely moving pieces carrying the of the partons from hard
scatterings. These flux tubes constitute eventually both bulk matter (which
thermalizes and flows) and jets. We introduce a criterion based on parton
energy loss to decide whether a given string segment contributes to the bulk or
leaves the matter to end up as a jet of hadrons. Essentially low
segments from inside the volume will constitute the bulk, high segments
(or segments very close to the surface) contribute to the jets. The latter ones
appear after the usual flux tube breaking via q-qbar production (Schwinger
mechanism). Interesting is the transition region: Intermediate segments
produced inside the matter close to the surface but having enough energy to
escape, are supposed to pick up q-qbar pairs from the thermal matter rather
than creating them via the Schwinger mechanism. This represents a communication
between jets and the flowing bulk matter (fluid-jet interaction). Also very
important is the interaction between jet hadrons and the soft hadrons from the
fluid freeze-out. We employ the new picture to investigate Pb-Pb collisions at
2.76 TeV. We discuss the centrality and dependence of particle
production and long range dihadron correlations at small and large
The muonic longitudinal shower profiles at production
In this paper the longitudinal profile of muon production along the shower
axis is studied. The characteristics of this distribution is investigated for
different primary masses, zenith angles, primary energies, and different high
energy hadronic models. It is found that the shape of this distribution
displays universal features similarly to what is known for the electromagnetic
profile. The relation between the muon production distribution and the
longitudinal electromagnetic evolution is also discussed
Parton-Based Gribov-Regge Theory
We present a new parton model approach for hadron-hadron interactions and, in particular, for the initial stage of nuclear collisions at very high energies (RHIC, LHC and beyond). The most important aspect of our approach is a self-consistent treatment, using the same formalism for calculating cross sections and particle production, based on an effective, QCD-inspired field theory, where many of the inconsistencies of presently used models will be avoided. In addition, we provide a unified treatment of soft and hard scattering, such that there is no fundamental cutoff parameter any more defining an artificial border between soft and hard scattering. Our approach cures some of the main deficiencies of two of the standard procedures currently used: the Gribov-Regge theory and the eikonalized parton model. There, cross section calculations and particle production cannot be treated in a consistent way using a common formalism. In particular, energy conservation is taken care of in case of particle production, but not concerning cross section calculations. In addition, hard contributions depend crucially on some cutoff, being divergent for the cutoff being zero. Finally, in case of several elementary scatterings, they are not treated on the same level: the first collision is always treated differently than the subsequent ones. All these problems are solved in our new approach
Strange Particles from NEXUS 3
After discussing conceptual problems with the conventional string model, we
present a new approach, based on a theoretically consistent multiple scattering
formalism. First results for strange particle production in proton-proton
scattering at 158 GeV and at 200 GeV (cms) are discussed.Comment: invited talk, given at the Strange Quark Matter Conference, Atlantic
Beach, North Carolina, March 12-17, 200
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