The Experts below are selected from a list of 234 Experts worldwide ranked by ideXlab platform
Enrico Vigezzi - One of the best experts on this subject based on the ideXlab platform.
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Conservation of the K-Quantum Number in warm nuclei
Nuclear Physics A, 2005Co-Authors: A. Bracco, G. Benzoni, S. Leoni, N. Blasi, F. Camera, C. Grassi, B. Million, A. Paleni, M. Pignanelli, Enrico VigezziAbstract:The selection rules on the K-Quantum Number in rapidly rotating warm nuclei are investigated analyzing quasi-continuum spectra feeding into low-K and high-K bands in 163Er. The data are compared to simulated spectra obtained using the band mixing model predictions including the residual interaction and a term representing the effect of the K-Quantum Number on the rotational energy. K-selection rules are found to be obeyed by the decay along excited unresolved rotational bands of heat energy up to around 1.2 MeV and angular momentum 30 ℏ ⩽ I ⩽ 40 ℏ . In contrast, the results corresponding to higher heat energy of 1.2 to 2.5 MeV indicate that the selection rules are only partially satisfied.
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Is the K-Quantum Number conserved in the order-to-chaos transition region?
Physics Letters B, 2005Co-Authors: G. Benzoni, A. Bracco, S. Leoni, N. Blasi, F. Camera, C. Grassi, B. Million, A. Paleni, M. Pignanelli, Enrico VigezziAbstract:To study the order-to-chaos transition in nuclei we investigate the validity of the K-Quantum Number in the excited rapidly rotating Er-163 nucleus, analyzing the variance and covariance of the spectrum fluctuations of gamma-cascades feeding into low-K and high-K bands. The data are compared to simulated spectra obtained using a microscopic cranked shell model. K-selection rules are found to be obeyed for decay along excited unresolved rotational bands of internal excitation energy up to around 1.2 MeV and angular momenta 20h
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Conservation of the K-Quantum Number in warm nuclei
Nuclear Physics A, 2004Co-Authors: A. Bracco, G. Benzoni, S. Leoni, N. Blasi, F. Camera, C. Grassi, B. Million, A. Paleni, M. Pignanelli, Enrico VigezziAbstract:he selection rules on the K-Quantum Number in rapidly rotating warm nuclei are investigated analyzing quasi-continuum spectra feeding into low-K and high-K bands in 163Er. The data are compared to simulated spectra obtained using the band mixing model predictions including the residual interaction and a term representing the effect of the K-Quantum Number on the rotational energy. K-selection rules are found to be obeyed by the decay along excited unresolved rotational bands of heat energy up to around 1.2 MeV and angular momentum 30Planck's over 2piless-than-or-equals, slantIless-than-or-equals, slant40Planck's over 2pi. In contrast, the results corresponding to higher heat energy of 1.2 to 2.5 MeV indicate that the selection rules are only partially satisfied.
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Violation and persistence of the K-Quantum Number in warm rotating nuclei
Nuclear Physics, 2004Co-Authors: M. Matsuo, A. Bracco, S. Leoni, T. Døssing, G.b. Hagemann, B. Herskind, Enrico VigezziAbstract:Abstract The validity of the K -Quantum Number in rapidly rotating warm nuclei is investigated as a function of thermal excitation energy U and angular momentum I , for the rare-earth nucleus 163 Er. The quantal eigenstates are described with a shell model which combines a cranked Nilsson mean-field and a residual two-body interaction, together with a term which takes into account the angular momentum carried by the K -Quantum Number in an approximate way. K -mixing is produced by the interplay of the Coriolis interaction and the residual interaction; it is weak in the region of the discrete rotational bands ( U ≲1 MeV), but it gradually increases until the limit of complete violation of the K -Quantum Number is approached around U ∼2–2.5 MeV. The calculated matrix elements between bands having different K -Quantum Numbers decrease exponentially as a function of Δ K , in qualitative agreement with recent data.
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Violation and persistence of the K-Quantum Number in warm rotating nuclei
Nuclear Physics A, 2004Co-Authors: M. Matsuo, A. Bracco, S. Leoni, T. Døssing, G.b. Hagemann, B. Herskind, Enrico VigezziAbstract:The validity of the K-Quantum Number in rapidly rotating warm nuclei is investigated as a function of thermal excitation energy U and angular momentum I, for the rare-earth nucleus 163Er. The quantal eigenstates are described with a shell model which combines a cranked Nilsson mean-field and a residual two-body interaction, together with a term which takes into account the angular momentum carried by the K-Quantum Number in an approximate way. K-mixing is produced by the interplay of the Coriolis interaction and the residual interaction; it is weak in the region of the discrete rotational bands (Uless, approximate1 MeV), but it gradually increases until the limit of complete violation of the K-Quantum Number is approached around Unot, vert, similar2\u20132.5 MeV. The calculated matrix elements between bands having different K-Quantum Numbers decrease exponentially as a function of \u394K, in qualitative agreement with recent data
C. W. J. Beenakker - One of the best experts on this subject based on the ideXlab platform.
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Scattering formula for the topological Quantum Number of a disordered multimode wire
Physical Review B, 2011Co-Authors: Ion Cosma Fulga, Fabian Hassler, Anton R. Akhmerov, C. W. J. BeenakkerAbstract:The topological Quantum Number Q of a superconducting or chiral insulating wire counts the Number of stable bound states at the end points. We determine Q from the matrix r of reflection amplitudes from one of the ends, generalizing the known result in the absence of time-reversal and chiral symmetry to all five topologically nontrivial symmetry classes. The formula takes the form of the determinant, Pfaffian, or matrix signature of r, depending on whether r is a real matrix, a real antisymmetric matrix, or a Hermitian matrix. We apply this formula to calculate the topological Quantum Number of N coupled dimerized polymer chains, including the effects of disorder in the hopping constants. The scattering theory relates a topological phase transition to a conductance peak, of quantized height and with a universal (symmetry class independent) line shape. Two peaks which merge are annihilated in the superconducting symmetry classes, while they reinforce each other in the chiral symmetry classes.
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PHYSICAL REVIEW B - Scattering formula for the topological Quantum Number of a disordered multimode wire
Physical Review B, 2011Co-Authors: Ion Cosma Fulga, Fabian Hassler, Anton R. Akhmerov, C. W. J. BeenakkerAbstract:The topological Quantum Number $Q$ of a superconducting or chiral insulating wire counts the Number of stable bound states at the end points. We determine $Q$ from the matrix $r$ of reflection amplitudes from one of the ends, generalizing the known result in the absence of time-reversal and chiral symmetry to all five topologically nontrivial symmetry classes. The formula takes the form of the determinant, Pfaffian, or matrix signature of $r$, depending on whether $r$ is a real matrix, a real antisymmetric matrix, or a Hermitian matrix. We apply this formula to calculate the topological Quantum Number of $N$ coupled dimerized polymer chains, including the effects of disorder in the hopping constants. The scattering theory relates a topological phase transition to a conductance peak, of quantized height and with a universal (symmetry class independent) line shape. Two peaks which merge are annihilated in the superconducting symmetry classes, while they reinforce each other in the chiral symmetry classes.
A. Bracco - One of the best experts on this subject based on the ideXlab platform.
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Conservation of the K-Quantum Number in warm nuclei
Nuclear Physics A, 2005Co-Authors: A. Bracco, G. Benzoni, S. Leoni, N. Blasi, F. Camera, C. Grassi, B. Million, A. Paleni, M. Pignanelli, Enrico VigezziAbstract:The selection rules on the K-Quantum Number in rapidly rotating warm nuclei are investigated analyzing quasi-continuum spectra feeding into low-K and high-K bands in 163Er. The data are compared to simulated spectra obtained using the band mixing model predictions including the residual interaction and a term representing the effect of the K-Quantum Number on the rotational energy. K-selection rules are found to be obeyed by the decay along excited unresolved rotational bands of heat energy up to around 1.2 MeV and angular momentum 30 ℏ ⩽ I ⩽ 40 ℏ . In contrast, the results corresponding to higher heat energy of 1.2 to 2.5 MeV indicate that the selection rules are only partially satisfied.
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Is the K-Quantum Number conserved in the order-to-chaos transition region?
Physics Letters B, 2005Co-Authors: G. Benzoni, A. Bracco, S. Leoni, N. Blasi, F. Camera, C. Grassi, B. Million, A. Paleni, M. Pignanelli, Enrico VigezziAbstract:To study the order-to-chaos transition in nuclei we investigate the validity of the K-Quantum Number in the excited rapidly rotating Er-163 nucleus, analyzing the variance and covariance of the spectrum fluctuations of gamma-cascades feeding into low-K and high-K bands. The data are compared to simulated spectra obtained using a microscopic cranked shell model. K-selection rules are found to be obeyed for decay along excited unresolved rotational bands of internal excitation energy up to around 1.2 MeV and angular momenta 20h
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Conservation of the K-Quantum Number in warm nuclei
Nuclear Physics A, 2004Co-Authors: A. Bracco, G. Benzoni, S. Leoni, N. Blasi, F. Camera, C. Grassi, B. Million, A. Paleni, M. Pignanelli, Enrico VigezziAbstract:he selection rules on the K-Quantum Number in rapidly rotating warm nuclei are investigated analyzing quasi-continuum spectra feeding into low-K and high-K bands in 163Er. The data are compared to simulated spectra obtained using the band mixing model predictions including the residual interaction and a term representing the effect of the K-Quantum Number on the rotational energy. K-selection rules are found to be obeyed by the decay along excited unresolved rotational bands of heat energy up to around 1.2 MeV and angular momentum 30Planck's over 2piless-than-or-equals, slantIless-than-or-equals, slant40Planck's over 2pi. In contrast, the results corresponding to higher heat energy of 1.2 to 2.5 MeV indicate that the selection rules are only partially satisfied.
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Violation and persistence of the K-Quantum Number in warm rotating nuclei
Nuclear Physics, 2004Co-Authors: M. Matsuo, A. Bracco, S. Leoni, T. Døssing, G.b. Hagemann, B. Herskind, Enrico VigezziAbstract:Abstract The validity of the K -Quantum Number in rapidly rotating warm nuclei is investigated as a function of thermal excitation energy U and angular momentum I , for the rare-earth nucleus 163 Er. The quantal eigenstates are described with a shell model which combines a cranked Nilsson mean-field and a residual two-body interaction, together with a term which takes into account the angular momentum carried by the K -Quantum Number in an approximate way. K -mixing is produced by the interplay of the Coriolis interaction and the residual interaction; it is weak in the region of the discrete rotational bands ( U ≲1 MeV), but it gradually increases until the limit of complete violation of the K -Quantum Number is approached around U ∼2–2.5 MeV. The calculated matrix elements between bands having different K -Quantum Numbers decrease exponentially as a function of Δ K , in qualitative agreement with recent data.
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Violation and persistence of the K-Quantum Number in warm rotating nuclei
Nuclear Physics A, 2004Co-Authors: M. Matsuo, A. Bracco, S. Leoni, T. Døssing, G.b. Hagemann, B. Herskind, Enrico VigezziAbstract:The validity of the K-Quantum Number in rapidly rotating warm nuclei is investigated as a function of thermal excitation energy U and angular momentum I, for the rare-earth nucleus 163Er. The quantal eigenstates are described with a shell model which combines a cranked Nilsson mean-field and a residual two-body interaction, together with a term which takes into account the angular momentum carried by the K-Quantum Number in an approximate way. K-mixing is produced by the interplay of the Coriolis interaction and the residual interaction; it is weak in the region of the discrete rotational bands (Uless, approximate1 MeV), but it gradually increases until the limit of complete violation of the K-Quantum Number is approached around Unot, vert, similar2\u20132.5 MeV. The calculated matrix elements between bands having different K-Quantum Numbers decrease exponentially as a function of \u394K, in qualitative agreement with recent data
S. Leoni - One of the best experts on this subject based on the ideXlab platform.
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Conservation of the K-Quantum Number in warm nuclei
Nuclear Physics A, 2005Co-Authors: A. Bracco, G. Benzoni, S. Leoni, N. Blasi, F. Camera, C. Grassi, B. Million, A. Paleni, M. Pignanelli, Enrico VigezziAbstract:The selection rules on the K-Quantum Number in rapidly rotating warm nuclei are investigated analyzing quasi-continuum spectra feeding into low-K and high-K bands in 163Er. The data are compared to simulated spectra obtained using the band mixing model predictions including the residual interaction and a term representing the effect of the K-Quantum Number on the rotational energy. K-selection rules are found to be obeyed by the decay along excited unresolved rotational bands of heat energy up to around 1.2 MeV and angular momentum 30 ℏ ⩽ I ⩽ 40 ℏ . In contrast, the results corresponding to higher heat energy of 1.2 to 2.5 MeV indicate that the selection rules are only partially satisfied.
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Is the K-Quantum Number conserved in the order-to-chaos transition region?
Physics Letters B, 2005Co-Authors: G. Benzoni, A. Bracco, S. Leoni, N. Blasi, F. Camera, C. Grassi, B. Million, A. Paleni, M. Pignanelli, Enrico VigezziAbstract:To study the order-to-chaos transition in nuclei we investigate the validity of the K-Quantum Number in the excited rapidly rotating Er-163 nucleus, analyzing the variance and covariance of the spectrum fluctuations of gamma-cascades feeding into low-K and high-K bands. The data are compared to simulated spectra obtained using a microscopic cranked shell model. K-selection rules are found to be obeyed for decay along excited unresolved rotational bands of internal excitation energy up to around 1.2 MeV and angular momenta 20h
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Conservation of the K-Quantum Number in warm nuclei
Nuclear Physics A, 2004Co-Authors: A. Bracco, G. Benzoni, S. Leoni, N. Blasi, F. Camera, C. Grassi, B. Million, A. Paleni, M. Pignanelli, Enrico VigezziAbstract:he selection rules on the K-Quantum Number in rapidly rotating warm nuclei are investigated analyzing quasi-continuum spectra feeding into low-K and high-K bands in 163Er. The data are compared to simulated spectra obtained using the band mixing model predictions including the residual interaction and a term representing the effect of the K-Quantum Number on the rotational energy. K-selection rules are found to be obeyed by the decay along excited unresolved rotational bands of heat energy up to around 1.2 MeV and angular momentum 30Planck's over 2piless-than-or-equals, slantIless-than-or-equals, slant40Planck's over 2pi. In contrast, the results corresponding to higher heat energy of 1.2 to 2.5 MeV indicate that the selection rules are only partially satisfied.
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Violation and persistence of the K-Quantum Number in warm rotating nuclei
Nuclear Physics, 2004Co-Authors: M. Matsuo, A. Bracco, S. Leoni, T. Døssing, G.b. Hagemann, B. Herskind, Enrico VigezziAbstract:Abstract The validity of the K -Quantum Number in rapidly rotating warm nuclei is investigated as a function of thermal excitation energy U and angular momentum I , for the rare-earth nucleus 163 Er. The quantal eigenstates are described with a shell model which combines a cranked Nilsson mean-field and a residual two-body interaction, together with a term which takes into account the angular momentum carried by the K -Quantum Number in an approximate way. K -mixing is produced by the interplay of the Coriolis interaction and the residual interaction; it is weak in the region of the discrete rotational bands ( U ≲1 MeV), but it gradually increases until the limit of complete violation of the K -Quantum Number is approached around U ∼2–2.5 MeV. The calculated matrix elements between bands having different K -Quantum Numbers decrease exponentially as a function of Δ K , in qualitative agreement with recent data.
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Violation and persistence of the K-Quantum Number in warm rotating nuclei
Nuclear Physics A, 2004Co-Authors: M. Matsuo, A. Bracco, S. Leoni, T. Døssing, G.b. Hagemann, B. Herskind, Enrico VigezziAbstract:The validity of the K-Quantum Number in rapidly rotating warm nuclei is investigated as a function of thermal excitation energy U and angular momentum I, for the rare-earth nucleus 163Er. The quantal eigenstates are described with a shell model which combines a cranked Nilsson mean-field and a residual two-body interaction, together with a term which takes into account the angular momentum carried by the K-Quantum Number in an approximate way. K-mixing is produced by the interplay of the Coriolis interaction and the residual interaction; it is weak in the region of the discrete rotational bands (Uless, approximate1 MeV), but it gradually increases until the limit of complete violation of the K-Quantum Number is approached around Unot, vert, similar2\u20132.5 MeV. The calculated matrix elements between bands having different K-Quantum Numbers decrease exponentially as a function of \u394K, in qualitative agreement with recent data
Masatoshi Imada - One of the best experts on this subject based on the ideXlab platform.
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Path-integral renormalization group method with Quantum-Number projection
Computer Physics Communications, 2005Co-Authors: Takahiro Mizusaki, Masatoshi ImadaAbstract:Abstract We present a Quantum-Number projection technique and its implementation to the recently proposed path-integral renormalization group (PIRG) method, which has been quite a powerful tool in investigating strongly correlated electron systems. By this extension, the PIRG can handle excited states with different Quantum Numbers in addition to the ground state and precision of solution is highly improved. By taking Hubbard models as an example, we demonstrate its feasibility.
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Quantum-Number projection in the path-integral renormalization group method
Physical Review B, 2004Co-Authors: Takahiro Mizusaki, Masatoshi ImadaAbstract:We present a Quantum-Number projection technique which enables us to exactly treat spin, momentum, and other symmetries embedded in the Hubbard model. By combining this projection technique, we extend the path-integral renormalization-group method to improve the efficiency of numerical computations. By taking numerical calculations for the standard Hubbard model and the Hubbard model with next-nearest-neighbor transfer, we show that the present extended method can extremely enhance numerical accuracy and that it can handle excited states, in addition to the ground state.
