Takeshi Osada

Improved Coulomb correction formulae for Bose-Einstein correlations

We present improved Coulomb correction formulae for Bose-Einstein correlations including also exchange term and use them to calculate appropriate correction factors for several source functions. It is found that Coulomb correction to the exchange function in the Bose-Einstein correlations cannot be neglected.

Modification of Eckart theory of relativistic dissipative fluid dynamics by introducing extended matching conditions

We deal with a novel approach to formulation of the relativistic dissipative hydrodynamics by extending the so-called matching conditions widely used in the literature. The form of the non-equilibrium entropy current can be determined by requiring thermodynamical stability of the entropy current under extended matching conditions. We derive equations of motion for the relativistic dissipative fluid based on the Eckart theory and show that linearized equations obtained from them are stable against small perturbations. It is also shown that the required fluid stability conditions are related to the causality of the model.

Nonextensive perfect hydrodynamics — a model of dissipative relativistic hydrodynamics?

We demonstrate that nonextensive perfect relativistic hydrodynamics (q-hydrodynamics) can serve as a model of the usual relativistic dissipative hydrodynamics (d-hydrodynamics) therefore facilitating considerably its applications. As an illustration, we show how using q-hydrodynamics one gets the q-dependent expressions for the dissipative entropy current and the corresponding ratios of the bulk and shear viscosities to entropy density, ζ/s and η/srespectively.

Coulomb corrections for Bose-Einstein correlations in whole momentum transfer region: proposal of seamless fitting

Abstract We applied an improved Coulomb correction method developed by us recently to data on identical KK -pairs production in S + Pb and p + Pb reactions at 200 GeV/c obtained by NA44 Collaboration. To analyse the whole range of the momentum transfers measured the method of “seamless fitting” has been proposed and used together with the asymptotic expansion formula for the Coulomb wave function. We found that such Coulomb corrections lead sometimes to different than previously reported (by NA44 Collaboration) interaction region and strongly influence the long range correlations.

Nonextensive/Dissipative Correspondence in Relativistic Hydrodynamics

We argue that there is profound correspondence (the nonextensive/dissipative correspondence - NexDC) between the perfect nonextensive hydrodynamics and the usual dissipative hydrodynamics which leads to simple expression for dissipative entropy current.

Quasiscaling in the analysis of the yield ratio {pi}{sup {minus}}/{pi}{sup +}: Mathematical structure and estimation of source size

Recently we have found that the integral of the squared Coulomb wave function describing a system composed of charged pion and central charged fragment Z{sub eff} protons, {vert_bar}{psi}{sub r}(r){vert_bar}{sup 2}, times pion source function {rho}(r) (of the size {beta}), {integral}dr{vert_bar}{psi}{sub r}(r){vert_bar}{sup 2}{rho}(r), shows a quasiscaling behavior. This is approximately invariant under the following transformation: ({beta},Z{sub eff}){r_arrow}({lambda}{beta},{lambda}Z{sub eff}); {lambda}{gt}0. We called such behavior {beta}-Z{sub eff} quasiscaling. We examine this quasiscaling behavior in detail. In particular we provide a semianalytical examination of this behavior and confirm it for the exponential pionic source functions in addition to the Gaussian ones and for the production of K mesons as well. When combined with the results of the Hanbury-Brown Twiss effect a result of the yield ratio allows us to estimate the size of the central charged fragment to be 125{le}Z{sub eff}{le}150 for Pb+Pb collisions at energy 158 GeV/nucleon. From our estimation, the baryon number density 0.024{le}n{sub B}{le}0.036 [1/fm{sup 3}] is obtained. {copyright} {ital 1997} {ital The American Physical Society}

Analyses of multiplicity distributions of e + e − and e - p collisions by means of a modified negative binomial distribution and Laguerre-type distribution: Interrelation of solutions in stochastic processes

A pure birth stochastic process with several initial conditions is considered.We analyze multiplicity distributions of e^+e^- collisions and e-p collisions, usigthe Modified Negative Binomial Distribution (MNBD) and the Laguerre-type distribution. Several multiplicity distributions show the same minimum \chi^2s values in analyses by means of two formulas: In these cases, we find that a parameter N contained in the MNBD becomes to be large. Taking large N limit in the MNBD, we find that the Laguerre-type distribution can be derived from it. Moreover, from the generalized MNBD we can also derive the generalized Glauber-Lachs formula. Finally stochastic properties of QCD and multiparticle dynamics are discussed.

Analysis of Bose-Einstein correlations in e⁺e⁻→W⁺W⁻ events including final state interactions

Recently DELPHI Collaboration reported new data on Bose-Einstein correlations (BEC) measured in e+e- ->W^+W^- events. Apparently no enhancement has been observed. We have analyzed these data including final state interactions (FSI) of both Coulomb and strong (s-wave) origin and found that there is enhancement in BEC but it is overshadowed by the FSI which are extremely important for those events. We have found the following values for the size of the interaction range beta and the degree of coherence lambda: beta=0.87 +/- 0.31fm and lambda=1.19 +/- 0.48, respectively.

ANALYSES OF MULTIPLICITY DISTRIBUTIONS BY MEANS OF THE MODIFIED NEGATIVE BINOMIAL DISTRIBUTION AND ITS KNO SCALING FUNCTION

We analyze various data of multiplicity distributions by means of the Modified Negative Binomial Distribution (MNBD) and its KNO scaling function, since this MNBD explains the oscillating behavior of the cumulant moment observed in e^+e^- annihilations, h-h collisions and e-p collisions. In the present analyses, we find that the MNBD(discrete distributions) describes the data of charged particles in e^+e^- annihilations much better than the Negative Binomial Distribution (NBD). To investigate stochastic property of the MNBD, we derive the KNO scaling function from the discrete distribution by using a straightforward method and the Poisson transform. It is a new KNO function expressed by the Laguerre polynomials. In analyses of the data by using the KNO scaling function, we find that the MNBD describes the data better than the gamma function.Thus, it can be said that the MNBD is one of useful formulas as well as NBD.We analyze various data of multiplicity distributions by means of the Modified Negative Binomial Distribution (MNBD) and its KNO scaling function, since this MNBD explains the oscillating behavior of the cumulant moment observed in e^+e^- annihilations, h-h collisions and e-p collisions. In the present analyses, we find that the MNBD(discrete distributions) describes the data of charged particles in e^+e^- annihilations much better than the Negative Binomial Distribution (NBD). To investigate stochastic property of the MNBD, we derive the KNO scaling function from the discrete distribution by using a straightforward method and the Poisson transform. It is a new KNO function expressed by the Laguerre polynomials. In analyses of the data by using the KNO scaling function, we find that the MNBD describes the data better than the gamma function.Thus, it can be said that the MNBD is one of useful formulas as well as NBD.