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Nuclear Theory·nucl-th

Monday·December 11, 2017

10 papers—6 primary·4 cross-listed

All10Primary6Cross-lists4
  1. 07

    [Submitted on 7 Dec 2017] (cross-list from hep-ph)

    What is the right formalism to search for resonances?

    JPAC Collaboration: M. Mikhasenko🇩🇪 · A. Pilloni🇺🇸 · J. Nys🇧🇪 · M. Albaladejo🇪🇸 · C. Fernandez-Ramirez🇲🇽 · A. Jackura🇺🇸 · V. Mathieu🇺🇸 · N. Sherrill🇺🇸 · T. Skwarnicki🇺🇸 · A. P. Szczepaniak🇺🇸

    Hadron decay chains constitute one of the main sources of information on the QCD spectrum. We discuss the differences between several partial wave analysis formalisms used in the literature to build the amplitudes. We match the helicity amplitudes to the covariant tensor basis. Hereby, we pay attention to the analytical properties of the amplitudes and separate singularities of kinematical and dynamical nature. We study the analytical properties of the spin-orbit (LS) formalism, and some of the covariant tensor approaches. In particular, we explicitly build the amplitudes for the B -> psi pi K and B -> Dbar pi pi decays, and show that the energy dependence of the covariant approach is model dependent. We also show that the usual recursive construction of covariant tensors explicitly violates crossing symmetry, which would lead to different resonance parameters extracted from scattering and decay processes.

    Comments:
    14 pages, 3 figures
    Subjects:
    High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Experiment (hep-ex); Nuclear Theory (nucl-th)
    arXiv:
    1712.02815 [pdf]
    EPJC(2018)·20 citations
  2. 08

    [Submitted on 7 Dec 2017] (cross-list from hep-ph)

    Parton correlations in double parton scattering

    Tomas Kasemets🇩🇪 · Sergio Scopetta🇮🇹

    Double parton scattering events are directly sensitive to the correlations between two partons inside a proton and can answer fundamental questions on the connections between the proton constituents. In this chapter, the different types of possible correlations, our present knowledge of them, and the processes where they are likely to be important, are introduced and explained. The increasing integrated luminosity at the LHC and the refinements of the theory of double parton scattering, lead to interesting prospects for measuring, or severely constraining, two-parton correlations in the near future.

    Comments:
    Prepared for: Multiple Parton Interactions at the LHC, Eds. P. Bartalini and J. R. Gaunt, World Scientific, Singapore; v2: references added
    Subjects:
    High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
    arXiv:
    1712.02884 [pdf]
    Adv.Ser.Direct.High Energy Phys.(2018)·20 citations
  3. 09

    [Submitted on 7 Dec 2017] (cross-list from nucl-ex)

    Elliptic Flow and the Nuclear Equation of State

    W. Trautmann🇩🇪 · H. H. Wolter🇩🇪

    New constraints for the nuclear equation of state at suprasaturation densities have been obtained by measuring collective particle flows in heavy-ion reactions at relativistic energies. Ratios and differences of neutron and hydrogen flows in 197Au + 197Au collisions at 400 MeV/nucleon were used in studies of the asymmetric-matter equation of state. The comparison with predictions of transport models favors a moderately soft to linear density dependence, consistent with ab-initio nuclear matter theories. Model predictions suggest that comprehensive data sets collected at higher bombarding energies will provide information on the asymmetric-matter equation of state in the density range up to two or three times the saturation value.

    Comments:
    20 pages, 9 figures, paper dedicated to the memory of Prof. Walter Greiner, to appear in Walter Greiner Memorial Volume (World Scientific). arXiv admin note: substantial text overlap with arXiv:1205.2585
    Subjects:
    Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
    arXiv:
    1712.03093 [pdf]
    4 citations
  4. 10

    [Submitted on 8 Dec 2017] (cross-list from hep-lat)

    Nuclear modification of scalar, axial and tensor charges from lattice QCD

    Emmanuel Chang🇺🇸 · Zohreh Davoudi🇺🇸 · William Detmold🇺🇸 · Arjun S. Gambhir🇺🇸 · Kostas Orginos🇺🇸 · Martin J. Savage🇺🇸 · Phiala E. Shanahan🇺🇸 · Michael L. Wagman🇺🇸 · Frank Winter🇺🇸

    Complete flavour decompositions of the scalar, axial and tensor charges of the proton, deuteron, diproton and He at SU(3)-symmetric values of the quark masses corresponding to a pion mass MeV are determined using lattice QCD. At the physical quark masses, the scalar charges constrain mean-field models of nuclei and the low-energy interactions of nuclei with potential dark matter candidates. The axial and tensor charges of nuclei constrain their spin content, integrated transversity and the quark contributions to their electric dipole moments. External fields are used to directly access the quark-line connected matrix elements of quark bilinear operators, and a combination of stochastic estimation techniques is used to determine the disconnected sea-quark contributions. Significant nuclear modifications are found, with particularly large, O(10%), effects in the scalar charges. Typically, these nuclear effects reduce the effective charge of the nucleon (quenching), although in some cases an enhancement is not excluded. Given the size of the nuclear modifications of the scalar charges resolved here, contributions from correlated multi-nucleon effects should be quantified in the analysis of dark matter direct-detection experiments using nuclear targets.

    Comments:
    published version
    Subjects:
    High Energy Physics — Lattice (hep-lat); High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
    arXiv:
    1712.03221 [pdf]
    PRL(2018)·67 citations

Affiliations

first authorsco-authorsvia INSPIRE