123084597
Universal relationship connecting various two-body effective residual interactions
Starting from a momentum space analysis of the two-body matrix elements, a relation has been established between the size of the model space actually used in a specific calculation and the relevant properties of the effective residual interaction. It turns out that the two-body transition density acts like a filter function on the Fourier transform of the force; it exhibits a distinct structure which clearly reflects the size and the detailed properties of the configuration space actually used. From an investigation of this filter function an equivalence criterion for different effective residual two-body interactions has been established both for closed and open shell nuclei. This result can be used to construct simple although realistic effective forces. As an example, a model for a separable residual interaction is proposed in which the corresponding parameters are being clearly related to the nuclear radius (i.e., the mass number), to the quantum numbers (i.e., the angular momentum) of the state under consideration and to the size of the configuration space used. For a number of examples this force has been applied successfully for the description of low energy properties of both closed and open shell nuclei. (AIP)
121918725
Meson-nucleus interaction - on the use of intensive meson beams for subnuclear research -
Abstract The use of intensive pion and kaon beams for subnuclear research is discussed. The goals of such investigations are briefly sketched and illustrated for some typical examples of specific flavour transfer reactions. It turns out that the meson beams which will be available at the proposed EHF will open up a new aera of subnuclear research. Such investigation touch upon quite fundamental questions of hadronic physics.
13703277
COLLECTIVE TREATMENT OF THE GIANT RESONANCES IN SPHERICAL NUCLEI.
In a collective treatment the energies of the giant resonances are given by the boundary conditions at the nuclear surface, which is subject to vibration in spherical nuclei. The general form of the coupling between these two collective motions is given by angular-momentum and parity conservation. The coupling constants are completely determined within the hydrodynamical model. In the present treatment the influence of the surface vibrations on the total photon-absorption cross section is calculated. It turns out that in most of the spherical nuclei this interaction leads to a pronounced structure in the cross section. The agreement with the experiments in medium-heavy nuclei is striking; many of the experimental characteristics are reproduced by the present calculations. In some nuclei, however, there seem to be indications of single-particle excitations which are not yet contained in this work.
118736183
Unified Description of Pion-Photo-Production and Elastic Pion Scattering on the Deuteron in the Isobar-Doorway Model
It has been recognized recently1 that the strong dominance of the Δ(1236) isobar in nuclear reactions at medium energies advocates an explicit treatment of this degree of freedom in nuclei (in contrast to its implicit incorporation in an optical model description). Such a model, phrased commonly as isobar doorway or A* model1 has two particularly interesting features, (i) it forms a natural basis for a unified description of different isobar dominated scattering processes; (ii) it offers a more or less direct test of the isobar self energy in nuclei or, equivalently, of the ΔN interaction. An ideal testing ground for such a model seems to be deuteron: with all many-body complications being absent, predictions for scattering reactions on the deuteron should reflect and in this way allow direct investigation of the various ingredients of the model.
117998395
Quark excitations of nuclei - A new frontier in nuclear research -
The investigation of nuclei in the energy domain of the elementary N*-resonances (i.e. for 200 MeV < Eexc < 2 GeV) opens up a new and important domain of nuclear research for essentially two reasons: (i) the quark structure of the nuclear constituent, the nucleon, leads to new nuclear phenomena; their investigation appears to be of fundamental importance for the understanding of complex hadronic systems; (ii) the nucleus can be used as a unique laboratory to test QCD in the nonasymptotic region where perturbative approaches fail. This is of particular interest, e.g. for the confinement problem. — Some specific aspects of subnuclear research are discussed in connection with the analysis of recent experiments and, in particular, in view of a possible strategy for a systematic investigation of nuclear quark excitations.
120745638
SHORT-RANGE CORRELATIONS AND ELASTIC ELECTRON SCATTERING.
119112898
Infrared scaling solutions beyond the Landau gauge: The maximally Abelian gauge and Abelian infrared dominance
Functional equations like exact renormalization group and Dyson-Schwinger equations have contributed to a better understanding of non-perturbative phenomena in quantum field theories in terms of the underlying Green functions. In Yang-Mills theory especially the Landau gauge has been used, as it is the most accessible gauge for these methods. The growing understanding obtained in this gauge allows to proceed to other gauges in order to obtain more information about the relation of different realizations of the confinement mechanism. In the maximally Abelian gauge first results are very encouraging as a variant of Abelian infrared dominance is found: The Abelian part of the gauge field propagator is enhanced at low momenta and thereby dominates the dynamics in the infrared. Its role is therefore similar to that of the ghost propagator in the Landau gauge, where one denotes the corresponding phenomenon as ghost dominance. Also the ambiguity of two different types of solutions (decoupling and scaling) exists in both gauges. Here we present how the two solutions are related in the maximally Abelian gauge. The intricacy of the system of functional equations in this gauge required the development of some new tools and methods as, for example, the automated derivation of the equations by the program DoFun. We also present results for linear covariant and ghost anti-ghost symmetric gauges.
118840672
Cosmic-ray monopole searches at Stanford using superconducting detectors.
119092260
Relativistic entanglement of two massive particles
We describe the spin and momentum degrees of freedom of a system of two massive spin-(1/2) particles as a four-qubit system. Then we explicitly show how the entanglement changes between different partitions of the qubits, when considered by different inertial observers. Although the two particle entanglement corresponding to a partition into Alice's and Bob's subsystems is, as often stated in the literature, invariant under Lorentz boosts, the entanglement with respect to other partitions of the Hilbert space on the other hand, is not. It certainly does depend on the chosen inertial frame and on the initial state considered. The change of entanglement arises, because a Lorentz boost on the momenta of the particles causes a Wigner rotation of the spin, which in certain cases entangles the spin with the momentum states. We systematically investigate the situation for different classes of initial spin states and different partitions of the four-qubit space. Furthermore, we study the behavior of Bell inequalities for different observers and demonstrate how the maximally possible degree of violation, using the Pauli-Lubanski spin observable, can be recovered by any inertial observer.
15272301
Detector commissioning for the CDMS-II final run at the Soudan Underground Laboratory
Abstract CDMS-II uses detectors known as Z-sensitive ionization phonons (ZIPs) to search for weakly interacting massive particles (WIMPs), a very promising candidate for the dark matter in the universe. The most recent data run utilized 12 ZIP detectors (six Ge and six Si) running for 1 2 year at the Soudan deep underground laboratory (780 m below surface), resulting in the current world's highest sensitivity to WIMP–nucleon coherent interaction [D.S. Akerib, et al., Phys. Rev. Lett. 93 (2004) 211301]. The CDMS-II experiment is approved to run 30 ZIPs until summer 2007 and its goal is to another order of magnitude increase in sensitivity to WIMPs. We present the detector preparation steps leading to the production of the CDMS-II detectors to be used in this final run.
119255416
How to determine the branch points of correlation functions in Euclidean space
Two-point correlators represented by either perturbative or non-perturbative integral equations in Euclidean space are considered. In general, it is difficult to determine the analytic structure of arbitrary correlators analytically. When relying on numerical methods to evaluate the analytic structure, exact predictions of, e.g., branch point locations (i.e., the multi-particle threshold) provide a useful check. These branch point locations can be derived by Cutkosky's cut rules. However, originally they were derived in Minkowski space for propagators with real masses and are thus not directly applicable in Euclidean space and for propagators of a more general form. Following similar considerations that led Karplus et al., Landau and Cutkosky more than 50 years ago to the mass summation formula that became known as Cutkosky's cut rules, we show how the position of branch points can be derived analytically in Euclidean space from propagators of very general form.