Engineering topics
Publications and source records attributed to Longacre, R. S..
Squeeze out happen when the expanding central fireball flows around a large surface flux tube in a central Au-Au collision at RHIC. We model such an effect in a flux tube model. Two particle correlations with respect to the v 2 axis formed by the soft fireball particles flowing around this large flux tube is a way of measuring the effect.
Hadron Molecules are particles made out of hadrons that are held together by self interactions. In this report we discuss seven such molecules and their self interactions. The f 0 (980), a 0 (980), f 1 (1400), ΔN(2150) and π 1 (1400) molecular structure is given. We predict that two more states the $K\bar{K}K$(1500) and a 1 (1400) should be found.
In this paper we explore the possibility of detecting strongly decaying exotic states. The dibaryon(2.15) J P = 2 + state which decays into d π is the example we use in this report.
In this paper we develop all the ingredients that come into play in the freeze-out of the heavy ion fireball for Au-Au collisions at $\sqrt{S_{NN}}$ =200 GeV into dipions. The resonance production of particles that decay into dipions plus minijets that also decay into dipions are explored. The final state re-scattering of the pions from minijets play an important role in the mass spectrum of the cocktail. Mass shifts due to minijet interference which depend on the volume of the re-scattering pions is presented. The effective mass balance function is explained. The dipion mass spectrum within a p t range(intermediate p t ) is fitted using thermal and minijet amplitudes.
The ultra-relativistic heavy ion collision starts out as a state of high density nuclear matter called the Quark Gluon Plasma(QGP) and expands rapidly to freeze-out. During the freeze out phase quarks and gluons form a system of strongly interacting hadrons. These hadrons continue to expand in a thermal manner until no further scattering is possible because the system becomes to dilute.
In this paper we use methods developed in Part 1 of The Dipion Cocktail, to fit the $p_t$ dependence of dipions for mid-central Au-Au collisions at $\sqrt{S_{NN}}$=200 GeV. For the minijet fragmentation part we use PYTHIA fragmentation as described in Part 1. For the thermal resonance production we use an exponential growth behavior. The interference between the direct production of dipion pairs from non-resonance minijet fragmentation and re-scattering through resonance states gives a measure of the size of the re-scattering region. This size is contain in the α parameter of Part1. We assumed a relationship between the α parameter and the mass shift of the ρ resonance. The data used for the fits comes from the RHIC collider as measured in the STAR experiment.