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Nuclear Theory·nucl-th

Thursday·June 25, 2015

7 papers—4 primary·3 cross-listed

All7Primary4Cross-lists3
  1. 01

    Equally Spaced Levels with T=1 two-body Matrix elements

    Wesley Pereira · Ricardo Garcia · Larry Zamick · Alberto Escuderos

    If one examines two-body matrix elements from experiment one notices that not only J=0 T=1 lies low but also J=1T=0 and J=J_{max} =2j T=0. It is sometimes thought that one needs both T=1 and T=0 two-body matrix elements to get equally spaced spectra of even I states i.e. vibraitonal spectra. We here attempt to get equally spaced levels with only those that have T=1 (even J).As an example we perform single-j calculations (f_{7/2}) in ^{44} T and ^{46} Ti. We then shift gears and decide to play around with the input two particle matrix, elements (not worrying about experiment) to generate interesting spectra e.g. rotaional spectra with and then without T=0 two-body matrix element. Of special interest is a new partial dynamical symmetry found when the "123", the "1234" etc.,interactions are used.

    nucl-th1 citation
  2. 02

    Impurity effects of particle on the 2 cluster states of Be and Be

    Masahiro Isaka · Masaaki Kimura

    The low-lying structure of Be and Be are investigated within the framework of the antisymmetrized molecular dynamics. We focus on the modifications of the excitation spectra and dynamical changes of the 2 cluster structure caused by a particle as an impurity in these hypernuclei. It is found that the excitation energies of well-pronounced cluster states are largely shifted up by the addition of a particle. Furthermore, we also find that the 2 cluster structure is significantly changed in the excited states, whereas it is almost unchanged in the ground states.

    nucl-thPRC(2015)·27 citations
  3. 03

    Analytical solutions for the Bohr Hamiltonian with the Woods-Saxon potential

    M. Capak · D. Petrellis · B. Gonul · Dennis Bonatsos

    Approximate analytical solutions in closed form are obtained for the 5-dimensional Bohr Hamiltonian with the Woods-Saxon potential, taking advantage of the Pekeris approximation and the exactly soluble one-dimensional extended Woods-Saxon potential with a dip near its surface. Comparison to the data for several gamma-unstable and prolate deformed nuclei indicates that the potential can describe well the ground state and gamma-1 bands of many prolate deformed nuclei corresponding to large enough "well size" and diffuseness, while it fails in describing the beta-1 bands, due to its lack of a hard core, as well as in describing gamma-unstable nuclei, because of the small "well size" and diffuseness they exhibit.

    nucl-thJ.Phys.G(2015)·37 citations
  4. 04

    Bohr Hamiltonian with a deformation-dependent mass term: physical meaning of the free parameter

    Dennis Bonatsos · N. Minkov · D. Petrellis

    Embedding of the 5-dimensional (5D) space of the Bohr Hamiltonian with a deformation-dependent mass (DDM) into a 6-dimensional (6D) space shows that the free parameter in the dependence of the mass on the deformation is connected to the curvature of the 5D space, with the special case of constant mass corresponding to a flat 5D space. Comparison of the DDM Bohr Hamiltonian to the 5D classical limit of Hamiltonians of the 6D interacting boson model (IBM), shows that the DDM parameter is proportional to the strength of the pairing interaction in the U(5) (vibrational) symmetry limit, while it is proportional to the quadrupole-quadrupole interaction in the SU(3) (rotational) symmetry limit, and to the difference of the pairing interactions among s, d bosons and d bosons alone in the O(6) (gamma-soft) limit. The presence of these interactions leads to a curved 5D space in the classical limit of IBM, in contrast to the flat 5D space of the original Bohr Hamiltonian, which is made curved by the introduction of the deformation-dependent mass.

    nucl-thJ.Phys.G(2015)·17 citations
  5. 05

    Light-Like Wilson Line in QCD Without Path Ordering

    Gouranga C. Nayak🇺🇸

    Unlike the Wilson line in QED the Wilson line in QCD contains path ordering. In this paper we get rid of the path ordering in the light-like Wilson line in QCD by simplifying all the infinite number of non-commuting terms in the SU(3) pure gauge. We prove that the light-like Wilson line in QCD naturally emerges when path integral formulation of QCD is used to prove factorization of soft and collinear divergences at all order in coupling constant in QCD processes at high energy colliders.

    ↳ hep-phhep-thnucl-thPhys.Part.Nucl.Lett.(2016)·31 citations
  6. 06

    Scattering off the Color Glass Condensate

    Heikki Mäntysaari🇫🇮

    In this thesis the Color Glass Condensate (CGC) framework, which describes quantum chromodynamics (QCD) at high energy, is applied to various scattering processes. Higher order corrections to the CGC evolution equations, known as the BK and JIMWLK equations, are also considered. It is shown that the leading order CGC calculations describe the experimental data from electron-proton deep inelastic scattering (DIS), proton-proton and proton-nucleus collisions. The initial condition for the BK evolution equation is obtained by performing a fit to deep inelastic scattering data. The fit result is used as an input to calculations of single particle spectra and nuclear suppression in proton-proton and proton-nucleus collisions, which are shown to be in agreement with RHIC and LHC measurements. In particular, the importance of a proper description of the nuclear geometry consistently with the DIS data fits is emphasized, as it results in a nuclear suppression factor which is consistent with the available experimental data. In addition to single particle production, the correlations between two hadrons at forward rapidity are computed. The RHIC measurements are shown to be naturally explainable in the CGC framework, and the previous CGC calculations are improved by including the so called inelastic and double parton scattering contributions. This improvement is shown to be required in order to get results compatible with the experimentally measured correlations. Exclusive vector meson production, which can be a powerful tool to study the gluonic structure of nuclei at small Bjorken-, is also considered. The cross sections are calculated within the CGC framework in the context of a future electron-ion collider. In particular, the cross section for incoherent diffractive vector meson production is derived and a centrality estimator for this process is proposed.

    ↳ hep-phnucl-th4 citations
  7. 07

    Investigating the domain of validity of the Gubser solution to the Boltzmann equation

    Ulrich W. Heinz🇺🇸 · Mauricio Martinez🇺🇸

    We study the evolution of the one particle distribution function that solves exactly the relativistic Boltzmann equation within the relaxation time approximation for a conformal system undergoing simultaneously azimuthally symmetric transverse and boost-invariant longitudinal expansion. We show, for arbitrary values of the shear viscosity to entropy density ratio, that the distribution function can become negative in certain kinematic regions of the available phase space depending on the boundary conditions. For thermal equilibrium initial conditions, we determine numerically the physical boundary in phase space where the distribution function is always positive definite. The requirement of positivity of this particular exact solution restricts its domain of validity, and it imposes physical constraints on its applicability.

    ↳ hep-phcond-mat.stat-mechhep-thnucl-thNPA(2015)·11 citations

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