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Nuclear Theory·nucl-th

Friday·May 8, 2015

6 papers—2 primary·4 cross-listed

All6Primary2Cross-lists4
  1. 01

    [Submitted on 7 May 2015]

    Symmetry energy at subsaturation densities and the neutron skin thickness of 208Pb

    Xiaohua Fan · Jianmin Dong · Wei Zuo

    The mass-dependent symmetry energy coefficients has been extracted by analysing the heavy nuclear mass differences reducing the uncertainties as far as possible in our previous work. Taking advantage of the obtained symmetry energy coefficient and the density profiles obtained by switching off the Coulomb interaction in , we calculated the slope parameter of the symmetry energy at the density of . The calculated ranges from 40.5 MeV to 60.3 MeV. The slope parameter of the symmetry energy at the density of is also calculated directly with Skyrme interactions for nuclear matter and is found to have a fine linear relation with the neutron skin thickness of , which is the difference of the neutron and proton rms radii of the nucleus. With the linear relation the neutron skin thickness of is predicted to be 0.15 - 0.21 fm.

    Comments:
    5 pages, 2 figures
    Subjects:
    Nuclear Theory (nucl-th)
    arXiv:
    1505.01563 [pdf]
    SCPMA(2015)·6 citations
  2. 02

    [Submitted on 7 May 2015]

    Effective Field Theory of Emergent Symmetry Breaking in Deformed Atomic Nuclei

    T. Papenbrock🇺🇸 · H. A. Weidenmüller🇩🇪

    Spontaneous symmetry breaking in non-relativistic quantum systems has previously been addressed in the framework of effective field theory. Low-lying excitations are constructed from Nambu-Goldstone modes using symmetry arguments only. We extend that approach to finite systems. The approach is very general. To be specific, however, we consider atomic nuclei with intrinsically deformed ground states. The emergent symmetry breaking in such systems requires the introduction of additional degrees of freedom on top of the Nambu-Goldstone modes. Symmetry arguments suffice to construct the low-lying states of the system. In deformed nuclei these are vibrational modes each of which serves as band head of a rotational band.

    Subjects:
    Nuclear Theory (nucl-th)
    arXiv:
    1505.01703 [pdf]
    J.Phys.G(2015)·11 citations
  3. 03

    [Submitted on 5 May 2015] (cross-list from hep-lat)

    Hagedorn spectrum and thermodynamics of SU(2) and SU(3) Yang-Mills theories

    Michele Caselle🇮🇹 · Alessandro Nada🇮🇹 · Marco Panero🇮🇹

    We present a high-precision lattice calculation of the equation of state in the confining phase of SU(2) Yang-Mills theory. We show that the results are described very well by a gas of massive, non-interacting glueballs, provided one assumes an exponentially growing Hagedorn spectrum. The latter can be derived within an effective bosonic closed-string model, leading to a parameter-free theoretical prediction, which is in perfect agreement with our lattice results. Furthermore, when applied to SU(3) Yang-Mills theory, this effective model accurately describes the lattice results reported by Borsányi et al. in JHEP 07 (2012) 056.

    Comments:
    1+19 pages, 4 pdf figures; v2: 1+22 pages, 4 pdf figures, improved discussion in sections 3 and 4, added references, corrected misprints: matches the journal version; v3: corrected a misprint, pointed out to us by Etsuko Itou, in the discussion of eq. (3.1), results unaffected
    Subjects:
    High Energy Physics — Lattice (hep-lat); High Energy Physics — Theory (hep-th); Nuclear Theory (nucl-th)
    arXiv:
    1505.01106 [pdf]
    JHEP(2015)·58 citations
  4. 04

    [Submitted on 6 May 2015] (cross-list from hep-ph)

    Extraction of the proton radius from electron-proton scattering data

    Gabriel Lee🇺🇸 · John R. Arrington🇺🇸 · Richard J. Hill🇺🇸

    We perform a new analysis of electron-proton scattering data to determine the proton electric and magnetic radii, enforcing model-independent constraints from form factor analyticity. A wide-ranging study of possible systematic effects is performed. An improved analysis is developed that rebins data taken at identical kinematic settings, and avoids a scaling assumption of systematic errors with statistical errors. Employing standard models for radiative corrections, our improved analysis of the 2010 Mainz A1 Collaboration data yields a proton electric radius fm and magnetic radius fm. A similar analysis applied to world data (excluding Mainz data) implies fm and fm. The Mainz and world values of the charge radius are consistent, and a simple combination yields a value fm that is larger than the CREMA Collaboration muonic hydrogen determination. The Mainz and world values of the magnetic radius differ by , and a simple average yields fm. The circumstances under which published muonic hydrogen and electron scattering data could be reconciled are discussed, including a possible deficiency in the standard radiative correction model which requires further analysis.

    Comments:
    26 pages, 10 figures, 4 supplementary data files with explanatory text. v2: As published in PRD including supplementary material. Added comparison to alternate model for correlated systematic errors and more references. Updated fit values with minor changes from v1
    Subjects:
    High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Experiment (hep-ex); Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th); Atomic Physics (physics.atom-ph)
    arXiv:
    1505.01489 [pdf]
    PRD(2015)·187 citations
  5. 05

    [Submitted on 6 May 2015] (cross-list from cond-mat.quant-gas)

    Pressure, compressibility, and contact of the two-dimensional attractive Fermi gas

    E. R. Anderson🇺🇸 · J. E. Drut🇺🇸

    Using ab initio lattice methods, we calculate the finite temperature thermodynamics of homogeneous two-dimensional spin-1/2 fermions with attractive short-range interactions. We present results for the density, pressure, compressibility, and quantum anomaly (i.e. Tan's contact) for a wide range of temperatures and coupling strengths, focusing on the unpolarized case. Within our statistical and systematic uncertainties, our prediction for the density equation of state differs quantitatively from the prediction by Luttinger-Ward theory in the strongly coupled region of parameter space, but otherwise agrees well with it. We also compare our calculations with the second- and third-order virial expansion, with which they are in excellent agreement in the low-fugacity regime.

    Comments:
    7 pages, 8 figures, including supplemental materials
    Subjects:
    Quantum Gases (cond-mat.quant-gas); High Energy Physics — Lattice (hep-lat); Nuclear Theory (nucl-th)
    arXiv:
    1505.01525 [pdf]
    PRL(2015)·44 citations
  6. 06

    [Submitted on 7 May 2015] (cross-list from hep-lat)

    High-precision calculation of the strange nucleon electromagnetic form factors

    Jeremy Green🇩🇪 · Stefan Meinel🇺🇸 · Michael Engelhardt🇺🇸 · Stefan Krieg🇩🇪 · Jesse Laeuchli🇺🇸 · John Negele🇺🇸 · Kostas Orginos🇺🇸 · Andrew Pochinsky🇺🇸 · Sergey Syritsyn🇺🇸

    We report a direct lattice QCD calculation of the strange nucleon electromagnetic form factors and in the kinematic range . For the first time, both and are shown to be nonzero with high significance. This work uses closer-to-physical lattice parameters than previous calculations, and achieves an unprecedented statistical precision by implementing a recently proposed variance reduction technique called hierarchical probing. We perform model-independent fits of the form factor shapes using the -expansion and determine the strange electric and magnetic radii and magnetic moment. We compare our results to parity-violating electron-proton scattering data and to other theoretical studies.

    Comments:
    6 pages, 5 figures. v2: references added
    Subjects:
    High Energy Physics — Lattice (hep-lat); High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
    arXiv:
    1505.01803 [pdf]
    PRD(2015)·89 citations

Affiliations

first authorsco-authorsvia INSPIRE