PaperPanorama
FAQ

Nuclear Theory·nucl-th

Tuesday·June 14, 2016

11 papers—6 primary·5 cross-listed

All11Primary6Cross-lists5
  1. 01

    [Submitted on 12 Jun 2016]

    Investigation of constraints on few-neutron forces in neutron matter by empirical information on the neutron skin of 48Ca and 208Pb

    Francesca Sammarruca🇺🇸

    The neutron matter equation of state is calculated from two-neutron forces up to fifth order of the chiral expansion and the order-by-order convergence of the predictions is investigated. Based on these equations of state, the binding energies and the neutron and proton density distributions in 208Pb and 48Ca are derived, with particular attention to the neutron skins, the focal point of this paper. Anticipating future experiments which will provide reliable information on the weak charge density in nuclei, the theoretical uncertainties and the possibility of constraining the size of few-neutron forces in neutron matter are discussed.

    Comments:
    Revised version accepted for publication in Physical Review C; 9 pages, 4 figures
    Subjects:
    Nuclear Theory (nucl-th)
    arXiv:
    1606.03648 [pdf]
    PRC(2016)·11 citations
  2. 02

    [Submitted on 13 Jun 2016]

    Consistency between SU(3) and SU(2) chiral perturbation theory for the nucleon mass

    Xiu-Lei Ren (Beihang U. & Peking U., SKLNPT)🇨🇳 · L. Alvarez-Ruso (Valencia U., IFIC)🇪🇸 · Li-Sheng Geng (Beihang U.)🇨🇳 · T. Ledwig (Valencia U., IFIC)🇪🇸 · Jie Meng (Beihang U. & Peking U., SKLNPT & Stellenbosch U.)🇨🇳 · M.J. Vicente Vacas (Valencia U. & Valencia U., IFIC)🇪🇸

    Treating the strange quark mass as a heavy scale compared to the light quark mass, we perform a matching of the nucleon mass in the SU(3) sector to the two-flavor case in covariant baryon chiral perturbation theory. The validity of the low-energy constants appearing in the octet baryon masses up to next-to-next-to-next-to-leading order~\cite{Ren:2014vea} is supported by comparing the effective parameters (the combinations of the couplings) with the corresponding low-energy constants in the SU(2) sector~\cite{Alvarez-Ruso:2013fza}. In addition, it is shown that the dependence of the effective parameters and the pion-nucleon sigma term on the strange quark mass is relatively weak around its physical value, thus providing support to the assumption made in Ref.~\cite{Alvarez-Ruso:2013fza}.

    Comments:
    11 pages, 1 table, 6, added reference, a few points clarified, matches the version accepted for publication
    Subjects:
    Nuclear Theory (nucl-th); High Energy Physics — Lattice (hep-lat); High Energy Physics — Phenomenology (hep-ph)
    arXiv:
    1606.03820 [pdf]
    PLB(2017)·16 citations
  3. 03

    [Submitted on 13 Jun 2016]

    Thermal blurring of event-by-event fluctuations provoked by rapidity conversion

    Yutaro Ohnishi🇯🇵 · Masakiyo Kitazawa🇯🇵 · Masayuki Asakawa🇯🇵

    We study the effect of thermal blurring caused by the use of (momentum-space) rapidity as a proxy of coordinate-space rapidity in experimental measurements of conserved charge fluctuations in relativistic heavy ion collisions. In theoretical studies assuming statistical mechanics, calculated fluctuations are those in a spatial volume. Experiments, on the other hand, can measure fluctuations only in a momentum-space in the final state. In a standard argument to compare experimental results for a momentum space with theoretical studies for a coordinate space, rapidities of particles are implicitly regarded as equivalent to their coordinate-space rapidity. We show that the relation of two fluctuations is significantly altered by the existence of the thermal motion, i.e. thermal blurring. We discuss that the thermal blurring can be regarded as a part of the diffusion process, and the effect can be understood by studying the rapidity window dependences of fluctuations. Centrality dependence of the thermal blurring effect is also discussed.

    Comments:
    9 pages, 7 figures; version accepted for publication in Phys. Rev. C, minor changes
    Subjects:
    Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph); Nuclear Experiment (nucl-ex)
    arXiv:
    1606.03827 [pdf]
    PRC(2016)·32 citations
  4. 04

    [Submitted on 13 Jun 2016]

    Perspective on the origin of hadron masses

    Craig D. Roberts🇺🇸

    The energy-momentum tensor in chiral QCD, , exhibits an anomaly, viz. . Measured in the proton, this anomaly yields , where is the proton's mass; but, at the same time, when computed in the pion, the answer is . Any attempt to understand the origin and nature of mass, and identify observable expressions thereof, must explain and unify these two apparently contradictory results, which are fundamental to the nature of our Universe. Given the importance of Poincaré-invariance in modern physics, the utility of a frame-dependent approach to this problem seems limited. That is especially true of any approach tied to a rest-frame decomposition of because a massless particle does not possess a rest-frame. On the other hand, the dynamical chiral symmetry breaking (DCSB) paradigm, connected with a Poincaré-covariant treatment of the continuum bound-state problem, provides a straightforward, simultaneous explanation of both these identities, and also a diverse array of predictions, testable at existing and proposed facilities. From this perspective, owing to exact, symmetry-driven cancellations which occur between one-body dressing effects and two-body-irreducible binding interactions in any well-defined computation of the forward scattering amplitude that defines this expectation value in the pseudoscalar meson. The cancellation is incomplete in any other hadronic bound state, with a remainder whose scale is set by the size of one-body dressing effects.

    Comments:
    12 pages, 2 figures. Contribution to a Topical Issue of Few Body Systems, celebrating the journal's 30th birthday
    Subjects:
    Nuclear Theory (nucl-th); High Energy Physics — Lattice (hep-lat); High Energy Physics — Phenomenology (hep-ph); Nuclear Experiment (nucl-ex)
    arXiv:
    1606.03909 [pdf]
    Few Body Syst.(2017)·97 citations
  5. 05

    [Submitted on 13 Jun 2016]

    From superdeformation to extreme deformation and clusterization in the N~Z nuclei of the A~40 mass region

    D. Ray · A. V. Afanasjev

    A systematic search for extremely deformed structures in the N~Z nuclei of the A~40 mass region has been performed for the first time in the framework of covariant density functional theory. At spin zero such structures are located at high excitation energies which prevents their experimental observation. The rotation acts as a tool to bring these exotic shapes to the yrast line or its vicinity so that their observation could become possible with future generation of tracking (or similar) detectors such as GRETA and AGATA. The major physical observables of such structures (such as transition quadrupole moments as well as kinematic and dynamic moments of inertia), the underlying single-particle structure and the spins at which they become yrast or near yrast are defined. The search for the fingerprints of clusterization and molecular structures is performed and the configurations with such features are discussed. The best candidates for observation of extremely deformed structures are identified. For several nuclei in this study (such as Ar), the addition of several spin units above currently measured maximum spin of will inevitably trigger the transition to hyper- and megadeformed nuclear shapes.

    Comments:
    27 pages, 35 figures, submitted to Physical Review C, supplemental material is provided in file supplement.pdf
    Subjects:
    Nuclear Theory (nucl-th)
    arXiv:
    1606.04019 [pdf]
    PRC(2016)·25 citations
  6. 06

    [Submitted on 13 Jun 2016]

    Factorization Breaking of for polarized deuteron targets in a relativistic framework

    Sabine Jeschonnek🇺🇸 · J. W. Van Orden🇺🇸

    We discuss the possible factorization of the tensor asymmetry measured for polarized deuteron targets within a relativistic framework. We define a reduced asymmetry and find that factorization holds only in plane wave impulse approximation and if p-waves are neglected. Our numerical results show a strong factorization breaking once final state interactions are included. We also compare the d-wave content of the wave functions with the size of the factored, reduced asymmetry and find that there is no systematic relationship of this quantity to the d-wave probability of the various wave functions.

    Subjects:
    Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph)
    arXiv:
    1606.04072 [pdf]
    PRC(2017)·5 citations

Affiliations

first authorsco-authorsvia INSPIRE