Interacting boson model parameters

The Importance of an Accurate Determination of Interacting Boson Model-2 Parameters... 

First, a brief description of the neutron-proton Interacting Boson Model (IBM-2) is given. Next, this model is applied to experimental data in order to determine its empirical parameters. Finally, we discuss why an accurate determination of these parameters is so important. 

Figure 4. The bridging between Bose-Einstein condensation in the low-density, weak interaction region and in the high-density, strong interaction region [124, 125]. Data for Tc/r , where is the critical temperature and T is the critical temperature in an ideal Bose-Einstein gas, were calculated from quantum path integral Monte-Carlo simulations for a hard-sphere many-boson model [124, 125], The effective dimensionless interaction parameter is pa, where p is the density and CT is the hard-core sphere diameter. The two open circles (o) represent experimental data for bulk liquid He.

The prediction of a heavy boson has received preliminary empirical support [92,96] from an anomaly in Z decay widths that points toward the existence of Z bosons with a mass of 812 GeV 1 33j [92,96] within the SO(l) grand unified field model, and a Higgs mechanism of 145 GeV4gj3. This suggests that a new massive neutral boson has been detected. Analysis of the hadronic peak cross sections obtained at LEP [96] implies a small amount of missing invisible width in Z decays. The effective number of massless neutrinos is 2.985 0.008, which is below the prediction of 3 by the standard model of electroweak interactions. The weak charge Qw in atomic parity violation can be interpreted as a measurement of the S parameter. This indicates a new Qw = 72.06 0.44, which is found to be above the standard model pre-... 

The IBM calculations use only two nuclear constituents, identical S and D bosons, or in the IBM-2, proton collective motion in a single formalism. Thus one might hope to be able to use the IBM to extrapolate from known properties of nuclei near the stability line to nuclei far from stability. The parameters are the total numbers of tt and v bosons, and Nv, and their one and two boson interactions. The usefulness of this theory for extrapolation depends on these parameters being Independent of N and Z, or known functions of N,Z. 

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