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Nuclear Theory·nucl-th

Monday·December 21, 2015

7 papers—5 primary·2 cross-listed

All7Primary5Cross-lists2
  1. 06

    [Submitted on 18 Dec 2015] (cross-list from hep-lat)

    The pole structure of the Lambda(1405) in a recent QCD simulation

    R. Molina🇺🇸 · M. Doring🇺🇸

    The baryon is difficult to detect in experiment, absent in many quark model calculations, and supposedly manifested through a two-pole structure. Its uncommon properties made it subject to numerous experimental and theoretical studies in recent years. Lattice-QCD eigenvalues for different quark masses were recently reported by the Adelaide group. We compare these eigenvalues to predictions of a model based on Unitary Chiral Perturbation Theory. The UCHPT calculation predicts the quark mass dependence remarkably well. It also explains the overlap pattern with different meson-baryon components, mainly and , at different quark masses. More accurate lattice QCD data are required to draw definite conclusions on the nature of the .

    Comments:
    14 pages, 4 figures
    Subjects:
    High Energy Physics — Lattice (hep-lat); Nuclear Theory (nucl-th)
    arXiv:
    1512.05831 [pdf]
    PRD(2016)·63 citations
  2. 07

    [Submitted on 18 Dec 2015] (cross-list from cond-mat.str-el)

    Polynomial Similarity Transformation Theory: A smooth interpolation between coupled cluster doubles and projected BCS applied to the reduced BCS Hamiltonian

    Matthias Degroote · Thomas M. Henderson · Jinmo Zhao · Jorge Dukelsky · Gustavo E. Scuseria

    We present a similarity transformation theory based on a polynomial form of a particle-hole pair excitation operator. In the weakly correlated limit, this polynomial becomes an exponential, leading to coupled cluster doubles. In the opposite strongly correlated limit, the polynomial becomes an extended Bessel expansion and yields the projected BCS wavefunction. In between, we interpolate using a single parameter. The effective Hamiltonian is non-hermitian and this Polynomial Similarity Transformation Theory follows the philosophy of traditional coupled cluster, left projecting the transformed Hamiltonian onto subspaces of the Hilbert space in which the wave function variance is forced to be zero. Similarly, the interpolation parameter is obtained through minimizing the next residual in the projective hierarchy. We rationalize and demonstrate how and why coupled cluster doubles is ill suited to the strongly correlated limit whereas the Bessel expansion remains well behaved. The model provides accurate wave functions with energy errors that in its best variant are smaller than 1\% across all interaction stengths. The numerical cost is polynomial in system size and the theory can be straightforwardly applied to any realistic Hamiltonian.

    Subjects:
    Strongly Correlated Electrons (cond-mat.str-el); Nuclear Theory (nucl-th)
    arXiv:
    1512.06111 [pdf]
    PRB(2016)·31 citations

Affiliations

first authorsco-authorsvia INSPIRE