The nucleon-nucleon triple scattering parameters for recoil particles

Relativistic formulae are obtained, expressing the polarization of the initially unpolarized particle in the scattering of an unpolarized nucleon on a polarized one, in terms of the polarization transfer tensor and in terms of the scattering matrix elements.On leave of absence from theFaculty of Technical and Nuclear Physics, Czech Technical University, Prague, Czechoslovakia.On leave of absence from theNuclear Research Institute of the Czechoslovak Academy of Sciences, e, Czechoslovakia.In conclusion the authors express their profound gratitude to S. M. Bilenky, L. I. Lapidus, R. M. Ryndin and Ya. A. Smorodinsky for useful discussions and to E. Dudova and J. Fingerova for help in the work.     

Effective nucleon-nucleon interactions and nuclear matter equation of state

Nuclear matter equations of state based on Skyrme, Myers-Swiatecki and Tondeur interactions are written as polynomials of the cubic root of density, with coefficients that are functions of the relative neutron excess δ. In the extrapolation toward states far away from the standard one, it is shown that the asymmetry dependence of the critical point ( ,) depends on the model used. However, when the equations of state are fitted to the same standard state, the value of is almost the same in Skyrme and in Myers-Swiatecki interactions, while is much lower in Tondeur interaction. Furthermore, does not depend sensitively on the choice of the parameter γ in Skyrme interaction. Received: 5 May 2000 / Accepted: 16 January 2001     

Strong enhancement of varepsilon(')/varepsilon through final state interactions

We quantify the important effect of strong final state interactions in the weak K-->2pi amplitudes, using the measured pi-pi phase shifts with J = 0 and I = 0,2. The final rescattering of the two pions provides a strong enhancement of the DeltaI = 1/2 amplitude, which so far has been neglected in the theoretical predictions of varepsilon(')/varepsilon. This correction increases the standard model prediction of varepsilon(')/varepsilon to values in good agreement with the experimental measurements.     

On the sensitivity of n-d scattering states to the nucleon-nucleon interaction

A new set of separable P-wave interactions and rank-2 tensor forces have been constructed and applied in three-body calculations for n-d elastic scattering at E_{n = 22.7 MeV}. A significant sensitivity of the polarizations to the different tensor forces and to the ³D₂ interaction has been found.     

On the investigation of nucleon-nucleon correlations by means of high-energy scattering

The possible effects of short-range dynamical nucleon-nucleon correlations on high-energy hadron scattering on ⁴He are examined. The Glauber theory of multiple scattering is used as the basis for the computations. The conclusion is that very small effects are to be expected for elastic and sum total inelastic scattering of commonly available projectiles.     

On the final state of spherical gravitational collapse

Following our recent finding [1] that, for the final state of continued spherical gravitational collapse of sufficiently massive bodies, the final gravitational mass of the fluidM _? → 0, we show that for a physical fluid the eventual value of 2M_?/R_? → 1 rather than 2M_?/R_?2M_?/R_? < 1 (the speed of light c = 1 and the gravitational constantG = 1), indicating the approach to a zero-mass black hole. We also point out that, as the final state is approached, the curvature components tend to blow up; also the proper radial distancel and the proper time (measured along a radial worldline) Τ → ∞, indicating that actually the singularity is never attained. We also identify that the final state may correspond to the local 3-speed attaining eitherV = 0 orV → c, even though invariant circumference contraction speedU =dR/dΤ → 0. Nonetheless, at a finite observation epoch, such Eternally Collapsing Objects (ECOs) may have a local speed of collapseV?c and the lab frame speed of collapse may be negligible because of high surface gravitational redshift. However, if quantum back reaction in the strong gravity regime would cause a phase transition of the form pressurep = - ρ, where ρ is the density of the collapsing fluid, it may be possible to have static Ultra Compact Objects (ûCOs) of arbitrary high mass [2]. While supposed Black Holes have no intrinsic magnetic field, ECOs or UCOs are likely to possess strong intrinsic magnetic fields, and we point out that there are already some tentative evidence for existence of such intrinsic magnetic fields in some Black Hole Candidates [3,4]. For the benefit of the readers who may not have gone through Paper I, we also include here the summary of the same. It clearly shows that the central result of Paper I can be derived even without knowing the meaning of the nomenclatureV or without imposing any of property ofV such as whetherV < 1 or not. In addition, we consolidate the same result from other physical considerations too.     

Extended sources,final state interactions and Bose-Einstein correlations

The isospin 2 ππ interaction is repulsive, thes-wave phase shift reaching ～?20° at the mass of the ρ meson. Theπ ^± π ^±correlation function shows a strong Bose-Einstein enhancement but no clear sign of this dynamical repulsion. I present the theory of final state interactions appropriate to particle production from an extended source and demonstrate that the data are entirely consistent with the known features of the ππI=2 interaction. The results are relevant to multiple pion production ine ⁺ e ^? annihilation, hadronic reactions and heavy ion collisions.     

Extended sources,final state interactions and Bose-Einstein Correlations

I extend the theory of Bose-Einstein correlations to the case where one of a pair of like pions is the daughter of resonance decay and include final state rescattering within the like pion pair. I consider critically the form of the isospin 2s-wave phase shift. The results of numerical calculations yield like pion correlation functions which are at best in marginal agreement with data frome ⁺ e ^? annihilation and proton-proton collisions. I show that the discrepancy which exists is removed by the effects of three (and more) particle rescattering. The quantitative interpretation of Bose-Einstein correlations among hadrons is very complicated unless the effective source size substantially exceeds 1 fm.     

J/Ψ suppression in relativistic heavy ion collisions through final state interactions with excited nucleons

TheJ/Ψ suppression in relativistic heavy ion collisions through final state interactions with excited state nucleons is estimated in a manner analogous to that of Gerschel and Hüfner for ground state nucleons. If excited state nucleons are larger in size than nucleons in their ground state, theJ/Ψ absorption cross section is increased. Because of relativistic time dilation this effect does not significantly alter theJ/Ψ suppression previously found.     

Energy dependence of nucleon-deuteron elastic scattering observables and its bearing on the3 P J nucleon-nucleon interactions

The energy dependence of neutron-deuteron elastic scattering observables has been calculated from 5 to 45 MeV via rigorous three-nucleon calculations using the Bonn B nucleon-nucleon interaction. The goal of these calculations was to identify energy and angular regions that may be investigated experimentally to study the question of charge-symmetry breaking in the³ P _J nucleon-nucleon forces and/or Coulomb interactions. It was found that the measurement of the neutron-deuteron elastic analyzing power at 16 and 22.7 MeV and its comparison to proton-deuteron data obtained at the same incident energy is the most promising case for studying the issue of charge-symmetry breaking in the³ P _J nucleon-nucleon forces and/or Coulomb interactions.     

On determination of the structural parameters of polydisperse magnetic fluids by small-angle neutron scattering

Factors affecting the determination of the structural parameters of polydisperse particles of typical magnetic fluids (MFs) from small-angle neutron scattering data (SANS), including the possible anisotropy of the particle shape and the residual incoherent background, are analyzed. It is shown that the effect of particle anisotropy on scattering must be considered in combination with the influence of their polydispersity. The relative shift in the MF’s structural parameters caused by particle anisotropy does not exceed 10–20% for particles with an anisotropy parameter which is less than four and becomes insignificant for more anisotropic particles. The main effect of the residual incoherent background of neutron scattering is related to determination of the thickness of the stabilizing shell and the generalized contrast parameter. It is shown that restrictions on the available maximum values of the scattering vector, measured in the experiment, lead to a relative shift in these parameters by up to 10%, while the other structural parameters (the average particle radius and the width of the size distribution) are determined with sufficiently high accuracy (the relative systematic error is 5% or less).     

Multiplicity structure of the hadronic final state in diffractive deep-inelastic scattering at HERA

The multiplicity structure of the hadronic system X produced in deep-inelastic processes at HERA of the type , where Y is a hadronic system with mass GeV and where the squared momentum transfer at the pY vertex, t, is limited to , is studied as a function of the invariant mass of the system X. Results are presented on multiplicity distributions and multiplicity moments, rapidity spectra and forward-backward correlations in the centre-of-mass system of X. The data are compared to results in annihilation, fixed-target lepton-nucleon collisions, hadro-produced diffractive final states and to non-diffractive hadron-hadron collisions. The comparison suggests a production mechanism of virtual photon dissociation which involves a mixture of partonic states and a significant gluon content. The data are well described by a model, based on a QCD-Regge analysis of the diffractive structure function, which assumes a large hard gluonic component of the colourless exchange at low . A model with soft colour interactions is also successful. Received: 27 April 1998 / Published online: 3 September 1998     

Direct experimental determination of the dispersion of a final state energy band

We report the first absolute and continous experimental determination of the dispersion of an unoccupied electron energy band in copper. This has been achieved by monitoring the extremal behaviour of binding energies in angular resolved photoelectron energy distribution curves obtained with a tunable light source. By this method the absolute value of the wave vector for transitions originating from the symmetry line ∑ was determined. The experiments confirm that the final state band deviates strongly from a parabola.     

Effect of density-dependent nucleon-nucleon cross-section on elastic scattering

A linear form of density-dependent total nucleon-nucleon (NN) cross-section that depends on the coordinates of the projectile and target is applied in the Glauber phase shift formula. The only free parameter in these calculations is the density-dependent parameter , which is adjusted to obtain an agreement between the calculated angular distribution of the elastic-scattering cross-section and the corresponding experimental one. The elastic scattering of the ¹²C ion on the ¹²C ion target has been studied at incident energies of 300, 360, 1016, 1441 and 2400 MeV. The total reaction cross-section is also calculated with the obtained value of for the same reactions. The obtained values of are compared with those obtained from the optical-model analysis as well as those of the experimental value. Nuclear transparency effects are also discussed. Generally, the density-dependent NN cross-section improves the calculated results.Received: 11 February 2003, Revised: 8 July 2003, Published online: 26 January 2004PACS: 24.10.-i Nuclear-reaction models and methods - 25.70.-z Low and intermediate energy heavy-ion reactions     

Microscopic approach to the nucleon-nucleon effective interaction and nucleon-nucleon scattering in symmetric and isospin-asymmetric nuclear matter

After reviewing our microscopic approach to nuclear and neutron-rich matter, we focus on how nucleon-nucleon scattering is impacted by the presence of a dense hadronic medium, with special emphasis on the case where neutron and proton densities are different. We discuss in detail medium and isospin asymmetry effects on the total elastic cross section and the mean free path of a neutron or a proton in isospin-asymmetric nuclear matter. We point out that in-medium cross sections play an important role in heavy-ion simulations aimed at extracting constraints on the symmetry potential. We argue that medium and isospin dependence of microscopic cross sections are the result of a complex balance among various effects, and cannot be simulated with a simple phenomenological model.     

Entropy and equilibrium property of QCD-instanton induced final state in deep-inelastic scattering

The scaling and additivity properties of Rényi entropy in rapidity space of the instanton final state (IFS) and current jet identified by the r-sorting method from the QCDINS Monte Carlo event sample are to saturation with decreasing phase space scale. Furthermore, it is found that the additivity of H2 holds well for the IFS in narrow rapidity windows at different positions. These results indicate that the IFS produced in the instanton-induced process of deep inelastic scattering has reached local equilibrium.