121598524
Collective resonance in pion-nucleus scattering
Pion-nucleus scattering is described by the excitation of bound nucleons into the ..delta.. resonance leading to isobaric resonances of the whole nucleus. A few broad collective resonances of different multipolarity are shown to dominate elastic and inelastic ..pi..-/sup 12/C scattering. From the qualitatively good agreement with the data, we conclude that those giant isobaric resonances are a general feature of the nuclear excitation spectrum in the ..delta.. (3, 3) energy range.
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.
120225283
Quark structure of simple and complex hadrons
Abstract A realistic description of the meson and baryon spectra can be achieved within a non-relativistic quark model but the coupling of baryonic q 3 -states to meson-baryon decay channels is of vital importance for a proper description of the decay properties of baryon resonances which are interpreted as bound (q 3 )-configurations embedded in meson continua. This dressing of q 3 -states automatically leads to an energy- and state dependent baryon-baryon interaction that allows a formulation of a multibaryon Hamiltonian for complex hadrons. Within this framework the subnuclear dynamics of intermediate energy excitations of complex hadrons is discussed.
120855950
Pionic and electromagnetic excitation of A* resonances
The nuclear excitation spectrum in the Delta (3,3) energy range is studied by comparing elastic pion scattering with coherent neutral pion photoproduction. The corresponding multipole excitation strength distributions are found to be quite different. This emphasises the role of the electromagnetic excitations of nuclei for the investigation of the A* resonances which is complementary to their mesonic excitation. Results are presented for 12C( gamma , pi 0) 12C(GS); they are compared with those of the phenomenological isobar doorway model and of DWIA calculations.
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.
19234257
Experimental realization of decoherence-free subspace in neutron interferometry.
A decoherence-free subspace (DFS) is an important class of quantum-error-correcting (QEC) codes that have been proposed for fault-tolerant quantum computation. The applications of QEC techniques, however, are not limited to quantum-information processing (QIP). Here we demonstrate how QEC codes may be used to improve experimental designs of quantum devices to achieve noise suppression. In particular, neutron interferometry is used as a test bed to show the potential for adding quantum error correction to quantum measurements. We built a five-blade neutron interferometer that incorporates both a standard Mach-Zender configuration and a configuration based on a DFS. Experiments verify that the DFS interferometer is protected against low-frequency mechanical vibrations. We anticipate these improvements will increase the range of applications for matter-wave interferometry.
161659804
PERFORMANCE AND BACKGROUND MEASUREMENTS OF THE CDMS II TOWER I DETECTORS AT THE STANFORD UNDERGROUND FACILITY
T. SAAB, P.L. BRINK, L. BAUDIS, B. CABRERA, J.P. CASTLE, ANDC. CHANGDepartment of Physics, Stanford University, Stanford, CA 94350, USAR. J. GAITSKELL AND J.P. THOMSONDepartment of Physics, Brown University, Providence, RI 02912, USAD.S. AKERIB, D. DRISCOLL, S. KAMAT, T.A. PERERA, R.W. SCHNEEAND G. WANGDepartment of Physics, Case Western Reserve University, Cleveland, OH44106, USAM. B. CRISLER, R. DIXON AND D. HOLMGRENFermi National Accelerator Laboratory, Batavia, IL 60510, USAJ.H. EMES, R.R. ROSS, A. SMITH AND G.W. SMITHLawrence Berkeley National Laboratory, Berkeley, CA 94720, USAJ.M. MARTINISNational Institute of Standards and Technology, Boulder, CO 80303, USAT. SHUTTDepartment of Physics, Princeton University, Princeton, NJ 08544, USAB.A. YOUNGDepartment of Physics, Santa Clara University, Santa Clara, CA 95053, USAM.S. ARMEL, V. MANDIC, P. MEUNIER, W. RAU, B. SADOULET ANDD.N. SEITZDepartment of Physics, University of California, Berkeley, Berkeley, CA 94720,
117035708
The SuperCDMS Experiment
Modest improvements in the level and/or discrimination of backgrounds are needed to keep backgrounds negligible during the three phases of SuperCDMS. By developing production designs that require only modest testing, detector production rates may be improved sufficiently to allow an exposure of 500 ton d within a reasonable time and budget. Overall, the improvement estimates described above are conservative. Previous development efforts have shown that some areas prove easier and provide larger factors while others prove more difficult. The conservative estimates together with the broad approach reduce the risk and give us confidence that we will succeed, providing the surest way to probe to WIMP-nucleon cross sections of 10{sup -46} cm{sup 2}.
6090781
Search for axions with the CDMS experiment.
We report on the first axion search results from the Cryogenic Dark Matter Search (CDMS) experiment at the Soudan Underground Laboratory. An energy threshold of 2 keV for electron-recoil events allows a search for possible solar axion conversion into photons or local galactic axion conversion into electrons in the germanium crystal detectors. The solar axion search sets an upper limit on the Primakov coupling g(agammagamma) of 2.4x10(-9) GeV-1 at the 95% confidence level for an axion mass less than 0.1 keV/c2. This limit benefits from the first precise measurement of the absolute crystal plane orientations in this type of experiment. The galactic axion search analysis sets a world-leading experimental upper limit on the axioelectric coupling g(aee) of 1.4x10(-12) at the 90% confidence level for an axion mass of 2.5 keV/c2.
55650213
A Dyson–Schwinger study of the four-gluon vertex
We present a self-consistent calculation of the four-gluon vertex of Landau gauge Yang–Mills theory from a truncated Dyson–Schwinger equation. The equation contains the leading diagrams in the ultraviolet and is solved using as the only input results for lower Green functions from previous Dyson–Schwinger calculations that are in good agreement with lattice data. All quantities are therefore fixed and no higher Green functions enter within this truncation. Our self-consistent solution resolves the full momentum dependence of the vertex but is limited to the tree-level tensor structure at the moment. Calculations of selected dressing functions for other tensor structures from this solution are used to exemplify that they are suppressed compared to the tree-level structure except for possible logarithmic enhancements in the deep infrared. Our results furthermore allow one to extract a qualitative fit for the vertex and a running coupling.
89606799
Lorentz invariance of entanglement classes in multipartite systems
We analyze multipartite entanglement in systems of spin-½ particles from a relativistic perspective. General conditions which have to be met for any classification of multipartite entanglement to be Lorentz invariant are derived, which contributes to a physical understanding of entanglement classification. We show that quantum information in a relativistic setting requires the partition of the Hilbert space into particles to be taken seriously. Furthermore, we study exemplary cases and show how the spin and momentum entanglement transforms relativistically in a multipartite setting.