117217506
A Two-Component Model for High Energy Collisions
We study a model for high-energy collisions in which two distinct and independent mechani sms are present: a) pionization, dep i cted as an excitation of the meson field induced by a classical source representing the i ncident particles in interaction, and b) fragmentation, descri bed as a two-stage process consisting in the incident - particle excitation and i ts subsequent decay. We show that the model exi hi bi t s an excellent agreement with all the ISR data on doel/dt, at, oinel and oel, and -+ its consistency with w do/&, and the fragmentation cross section is discussed.
123638527
Comparison between classification using impact parameter and using number of participants in relativistic nuclear collisions
Using the hydrodynamical code NeXSPheRIO, we compare predictions as usually done in hydrodynamics, using centrality windows defined through the impact parameter, and as obtainable experimentally, using windows in participant number.
54658857
Antihyperon polarization in inclusive processes at high energies
We propose a model that we believe is the main source of the antihyperon polarization in high-energy protonnucleus inclusive reactions. The polarization is originated by the final-state interactions between the antihyperons and other produced particles in these collisions (predominantly pions). The model is based on two elements: the low-energy pion-hyperon interaction (described by chiral effective Lagrangians) and the statistical fluctuations plus expansion of the background matter.
28948810
Hydrodynamic evolution near QCD critical point
Some consequences of the presence of critical point in the equation of state on the hydrodynamical evolution of the strongly interacting matter are discussed. For this purpose, we apply the low energy effective theory of QCD, the Nambu-Jona-Lasinio model and show some examples.
14013912
Coulomb effect: A possible probe for the evolution of hadronic matter
Electromagnetic field produced in high-energy heavy-ion collisions contains much useful information, because the field can be directly related to the motion of the matter in the whole stage of the reaction. One can divide the total electromagnetic field into three parts, i.e., the contributions from the incident nuclei, non-participating nucleons and charged fluid, the latter consisting of strongly interacting hadrons or quarks. Parametrizing the space-time evolution of the charged fluid based on hydrodynamic model, we study the development of the electromagnetic field which accompanies the high-energy heavy-ion collisions. We found that the incident nuclei bring a rather strong electromagnetic field to the interaction region of hadrons or quarks over a few fm after the collision. On the other hand, the observed charged hadrons' spectra are mostly affected (Coulomb effect) by the field of the charged fluid. We compare the result of our model with experimental data and found that the model reproduces them well. The pion yield ratio pi^-/pi+ at a RHIC energy, Au+Au 100+100 GeV/nucleon, is also predicted.
16801184
Fluctuations in hadronic and nuclear collisions
We investigate several fluctuation effects in high-energy hadronic and nuclear collisions through the analysis of different observables. To introduce fluctuations in the initial stage of collisions, we use the interacting gluon model (IGM) modified by the inclusion of the impact parameter. The inelasticity and leading-particle distributions follow directly from this model. The fluctuation effects on rapidity distributions are then studied using Landau's hydrodynamic model in one dimension. To investigage further the effects of the multiplicity fluctuation, we use the longitudinal phase-space model, with the multiplicity distribution calculated within the hydrodynamic model, and the initial conditions given by the IGM. Forward-backward correlation is obtained in this way.
150379990
Development of Soft X-ray Source using Laser Compton Scattering
Soft X-ray source using a laser Compton scattering between a 5MeV electron beam and a Nd:YLF laser light (1047nm) has been developed at Waseda University. Generated X-ray energy was analytically calculated to be 435eV in the 20° interaction, 333eV in the 60° interaction and 222eV in the 90° interaction with the energy band width of less than 0.39%. The energy of these X-ray is included in the range of “water window” so that these Xray is useful for the biological observation. The maximum number of x-ray is analytically estimated to be 1.8 ×10 at 435eV with 0.39% energy band-width. As the preliminary experiment, Timing adjustment between the electron beam and the laser light and background measurements of detector were performed.