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Search Results: 1 - 10 of 87754 matches for " I. Slaus "
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Comment on Neutron-Proton Spin-Correlation Parameter A_{ZZ} at 68 Mev
R. Machleidt,I. Slaus
Physics , 1993, DOI: 10.1103/PhysRevLett.72.2664
Abstract: We present two arguments indicating that the large value for the $\epsilon_1$ mixing parameter at 50 MeV, which the Basel group extracted from their recent $A_{zz}$ measurement, may be incorrect. First, there are nucleon-nucleon (NN) potentials which predict the $\epsilon_1$ at 50 MeV substantially below the Basel value and reproduce the Basel $A_{zz}$ data accurately. Second, the large value for $\epsilon_1$ at 50 MeV proposed by the Basel group can only be explained by a model for the NN interaction which is very unrealistic (no $\rho$-meson and essentially a point-like $\pi NN$ vertex) and overpredicts the $\epsilon_1$ in the energy range where it is well determined (150--500 MeV) by a factor of two.
The nucleon-nucleon interaction
R. Machleidt,I. Slaus
Physics , 2001, DOI: 10.1088/0954-3899/27/5/201
Abstract: We review the major progress of the past decade concerning our understanding of the nucleon-nucleon interaction. The focus is on the low-energy region (below pion production threshold), but a brief outlook towards higher energies is also given. The items discussed include charge-dependence, the precise value of the $\pi NN$ coupling constant, phase shift analysis and high-precision NN data and potentials. We also address the issue of a proper theory of nuclear forces. Finally, we summarize the essential open questions that future research should be devoted to.
Few Body Reserch - Summary
Ivo Slaus
Physics , 2006, DOI: 10.1016/j.nuclphysa.2007.03.038
Abstract: Few-body research history, achievements, current development and challenges are presented.
A study of nucleon-deuteron elastic scattering in configuration space
V. M. Suslov,M. A. Braun,I. N. Filikhin,B. Vlahovic,I. Slaus
Physics , 2010,
Abstract: A new computational method for solving the nucleon-deuteron breakup scattering problem has been applied to study the elastic neutron- and proton-deuteron scattering on the basis of the configuration-space Faddeev-Noyes-Noble-Merkuriev equations. This method is based on the spline-decomposition in the angular variable and on a generalization of the Numerov method for the hyperradius. The Merkuriev-Gignoux-Laverne approach has been generalized for arbitrary nucleon-nucleon potentials and with an arbitrary number of partial waves. The nucleon-deuteron observables at the incident nucleon energy 3 MeV have been calculated using the charge-independent AV14 nucleon-nucleon potential including the Coulomb force for the proton-deuteron scattering. Results have been compared with those of other authors and with experimental proton-deuteron scattering data.
Faddeev calculation for breakup neutron-deuteron scattering at 14.1 MeV lab energy
V M Suslov,I Filikhin,B Vlahovic,M A Braun,I Slaus
Physics , 2013,
Abstract: A new computational method for solving the nucleon-deuteron breakup scattering problem has been applied to study the inelastic neutron-deuteron scattering on the basis of the configuration-space Faddeev equations. This method is based on the spline-decomposition in the angular variable and on a generalization of the Numerov method for the hyperradius. The Merkuriev-Gignoux-Laverne approach has been generalized for arbitrary nucleon-nucleon potentials and with an arbitrary number of partial waves. Neutron-deuteron observables at the incident nucleon energy 14.1 MeV have been calculated using the charge-independent AV14 nucleon-nucleon potential. Results have been compared with those of other authors and with experimental neutron-deuteron scattering data.
Indicators of Economic Progress: The Power of Measurement and Human Welfare
Garry Jacobs,Ivo Slaus
Cadmus , 2010,
Abstract: Right measurement is a powerful instrument for social progress; wrong or imprecise measurement a source of hazard and even havoc. The essential purpose of economic activity is the promotion of human development, welfare and well-being in a sustainable manner, and not growth for growth’s sake, yet we lack effective measures to monitor progress toward these objectives. Advances in understanding, theory and measurement must necessarily proceed hand in hand. A companion article in this publication sets forth the urgent need for new theory in economics. This article sets forth the complementary need for new measures. The stakes are high and the choice is ours. On one side, rising social tensions, recurring financial crises and ecological disaster; on the other, the progressive unfolding and development of human capacity in harmony with Nature. The deficiencies of GDP as a measure are well-documented by leading economists Kuznets, Tobin, Tinbergen and many others; but, unfortunately, decision-making still remains largely based on GDP, valid during 1930-70 perhaps, but certainly inappropriate today. The challenge is to derive more appropriate indicators to reflect real, sustainable economic welfare, social development and human wellbeing. The attributes that have made GDP so successful are often overlooked — it provides clear objectives for policy and decision-making. We propose new composite indicator, HEWI, which can be used to guide decision-making, which retains the strengths associated with GDP, while substantially enhancing its value as a measure of human economic development. HEWI monitors progress on factors that contribute prominently to present economic welfare — household consumption, government welfare-related expenditure, income inequality and unemployment — as well as factors that have the potential to significantly enhance long term sustainability — education, fossil fuel energy efficiency and net household savings. The index is applied to assess the economic performance of select countries from 1985-2005.
eta N S-wave scattering length in a three coupled channel, multiresonance, unitary model
Mijo Batinic,Ivo Slaus,Alfred Svarc
Physics , 1995, DOI: 10.1103/PhysRevC.52.2188
Abstract: The S-wave scattering length for eta-N elastic scattering is extracted from the S-wave T-matrix in a three coupled channel, multiresonance unitary model. Results are compared with values already reported in literature which are obtained applying multichannel, but single resonance -- no background models. A dispersion among the previously published values of the real part of the S-wave scattering length is observed. We demonstrate that the reported spread originates from the strong sensitivity of the scattering length upon the small variation of the used input resonance parameters. In addition, we show that eta-N scattering length value obtained in single resonance -- no background models significantly increases if background term is added in a unitary way. We question the reliability of previously reported values based only on the single resonance -- no background models, and demonstrate that the value of the eta-N S-wave scattering length obtained in this publication is much more realistic because of the multiresonance and unitary approach.
Ratios of Elastic Scattering of Pions from 3H and 3He
W. J. Briscoe,B. L. Berman,R. W. C. Carter,K. S. Dhuga,S. K. Matthews,N-J. Nicholas,S. J. Greene,B. M. K. Nefkens,J. W. Price,L. D. Isenhower,M. E. Sadler,I. Slaus,I. Supek
Physics , 2002, DOI: 10.1103/PhysRevC.66.054006
Abstract: We have measured the elastic-scattering ratios of normalized yields for charged pions from 3H and 3He in the backward hemisphere. At 180 MeV, we completed the angular distribution begun with our earlier measurements, adding six data points in the angular range of 119 deg to 169 deg in the pi-nucleus center of mass. We also measured an excitation function with data points at 142, 180, 220, and 256 MeV incident pion energy at the largest achievable angle for each energy between 160 deg and 170 deg in the pi-nucleus center of mass. This excitation function corresponds to the energies of our forward-hemisphere studies. The data, taken as a whole, show an apparent role reversal of the two charge-symmetric ratios r1 and r2 in the backward hemisphere. Also, for data > 100 deg we observe a strong dependence on the four-momentum transfer squared (-t) for all of the ratios regardless of pion energy or scattering angle, and we find that the superratio R data match very well with calculations based on the forward-hemisphere data that predicts the value of the difference between the even-nucleon radii of 3H and 3He. Comparisons are also made with recent calculations incorporating different wave functions and double scattering models.
A New Measurement of the 1S0 Neutron-Neutron Scattering Length using the Neutron-Proton Scattering Length as a Standard
D. E. Gonzalez Trotter,F. Salinas,Q. Chen,A. S. Crowell,W. Gloeckle,C. R. Howell,C. D. Roper,D. Schmidt,I. Slaus,H. Tang,W. Tornow,R. L. Walter,H. Witala,Z. Zhou
Physics , 1999, DOI: 10.1103/PhysRevLett.83.3788
Abstract: The present paper reports high-accuracy cross-section data for the 2H(n,nnp) reaction in the neutron-proton (np) and neutron-neutron (nn) final-state-interaction (FSI) regions at an incident mean neutron energy of 13.0 MeV. These data were analyzed with rigorous three-nucleon calculations to determine the 1S0 np and nn scattering lengths, a_np and a_nn. Our results are a_nn = -18.7 +/- 0.6 fm and a_np = -23.5 +/- 0.8 fm. Since our value for a_np obtained from neutron-deuteron (nd) breakup agrees with that from free np scattering, we conclude that our investigation of the nn FSI done simultaneously and under identical conditions gives the correct value for a_nn. Our value for a_nn is in agreement with that obtained in pion-deuteron capture measurements but disagrees with values obtained from earlier nd breakup studies.
pi N --> eta N and eta N --> eta N partial wave T-matrices in a coupled, three channel model
Mijo Batinic,Ivo Slaus,Alfred Svarc,B. M. K. Nefkens
Physics , 1995, DOI: 10.1103/PhysRevC.57.1004
Abstract: The pi N --> eta N and eta N --> eta N partial wave T-matrices for the eight lowest partial waves have been obtained in a three coupled channel model with unitarity manifestly imposed. The two physical channels are pi_N and eta_N, and the third channel, pi_pi_N is an effective, but unphysical two body channel which represents all remaining processes. The pi_N elastic phase shifts and the weighted data base of the pi- p --> eta n total and differential cross sections are chosen as the input for the fitting procedure. A model containing a single resonance in each of the three partial waves that dominates the eta production at lower energies is compared with previous analyses, based on similar assumptions. A multiresonance coupled channel model is introduced which significantly improves the agreement with all input data. Our results are compared with a complementary multiresonance coupled channel analysis that is constrained with elastic and continuum production channels. The inclusion of the fourth P11 resonance in the 1440 - 2200 MeV region further improves the agreement between the analysis and the data.
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