Hiroki Nakamura

Electron- and neutrino-nucleus scattering in the impulse approximation regime

A quantitative understanding of the weak nuclear response is a prerequisite for the analyses of neutrino experiments such as K2K and MiniBOONE, which measure energy and angle of the muons produced in neutrino-nucleus interactions in the energy range 0.5-3 GeV and reconstruct the incident neutrino energy to determine neutrino oscillations. In this paper we discuss theoretical calculations of electron- and neutrino-nucleus scattering, carried out within the impulse approximation scheme using realistic nuclear spectral functions. Comparison between electron scattering data and the calculated inclusive cross section of oxygen, at beam energies ranging between 700 and 1200 MeV, show that the Fermi gas model, widely used in the analysis of neutrino oscillation experiments, fails to provide a satisfactory description of the measured cross sections, and inclusion of nuclear dynamics is needed.

Two- and three-pion interferometry for a nonchaotic source in relativistic nuclear collisions

Two- and three-pion correlation functions are investigated for a source that is not fully chaotic. Various models are examined to describe the source. The chaoticity and weight factor are evaluated in each model as measures of the strength of correlations and compared to experimental results. A new measure of three-pion correlation is also suggested.

Quasi-elastic neutrino-nucleus scattering and spectral function

Abstract The quasi-elastic cross sections of 16 O(ν, μ − ) and 16 O(ν, p ) are calculated in the plane-wave impulse approximation using a realistic spectral function, and are compared with the cross sections calculated using the relativistic Fermi gas models. The contributions due to the Δ resonance formation are also examined.

Numerical analysis of a two-pion correlation function based on a hydrodynamical model

We will numerically investigate two-particle correlation function of CERN– SPS 158 A GeV Pb+Pb central collisions in detail based on a (3+1)dimensional relativistic hydrodynamical model with first order phase transition. We use the Yano-Koonin-Podgoretskiuo parametrization as well as the usual Cartesian parametrization and analyze the pair momentum dependence of HBT radii extracted from the parametrizations. We find that the interpretation of the temporal radius parameters as the time duration in YKP parametrization is not available for the hydrodynamical model where the source became opaque naturally because of expansion and surface dominant freeze-out. Finally, effect of the phase transition on the source opacity is also discussed.

Numerical Analyses of CERN 200 GeV/A Heavy-Ion Collisions Based on a Hydrodynamical Model with Phase Transition

We numerically analyze recent high energy heavy-ion collision experiments based on a hydrodynamical model with phase transition and discuss a systematic change of initial state of QGP-fluid depending on colliding-nucleis mass. In a previous paper, we formulated a (3+1)-dimensional hydrodynamical model for quark-gluon plasma with phase transition and discussed numerically the space-time evolution in detail. We here compare the numerical solution with the hadronic distributions given by CERN WA80 and NA35. Systematic analyses of the experiments with various colliding nuclei enable us to discuss the dependences of the initial parameters of the hydrodynamical model on colliding nucleis mass. Furthermore, extrapolating the present experiments, we derive the possible hadronic distributions for lead-lead 150GeV/A collision.

Effects of disoriented chiral condensates on two- and three-pion correlations of relativistic nuclear collisions

Two- and three-pion correlations are investigated in cases when a disoriented chiral condensate (DCC) occurs. A chaoticity and weight factor are used as measures of two- and three-pion correlations, and the various models for the DCC are investigated. Some models are found to yield the chaoticity and weight factor in a reasonable agreement with recent experimental data.

Multiplicity Dependence of Partially Coherent Pion Production in Relativistic Heavy Ion Collisions

We investigate two- and three-particle intensity correlation functions of pions in relativistic heavy ion collisions for different colliding energies. Based on three models of particle production, we analyze the degree to which the pion sources are chaotic in the SPS S+Pb, Pb+Pb and the RHIC Au+Au collisions. The chaoticity, A, of the two-particle correlation functions is corrected for long-lived resonance decays. The effect of the partial Coulomb correction is also examined. Although the partially coherent model gives a result which is consistent with that of STAR, the chaotic fraction does not exhibit clear multiplicity dependence if we take into account both the corrected chaoticity and the weight factor of the three-pion correlation function. The result of the partially-multicoherent model indicates an increasing number of coherent sources in higher multiplicity events.

Source Chaoticity from Two- and Three-Pion Correlations in Au+Au collisions at

We consistently analyze two-pion correlation functions and three-pion correlation functions of 130

Three-pion interferometry of relativistic nuclear collisions

A

Source chaoticity in relativistic heavy ion collisions at SPS and RHIC

GeV Au+Au collisions measured at RHIC, applying three models of partially coherent pion sources. The effect of long-lived resonances on the chaoticity in the two-pion correlation function is estimated on the basis of a statistical model. We find that the chaoticity extracted from the three-pion correlation function is consistent with that extracted from the two-pion correlation function at vanishing relative momenta after the subtraction of the contribution of the long-lived resonance decays. nAll three models indicate that pions are emitted from the mixture of a chaotic source and coherent sources in the 130