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Nuclear Theory·nucl-th

Wednesday·January 10, 2018

4 papers—2 primary·2 cross-listed

All4Primary2Cross-lists2
  1. 01

    [Submitted on 9 Jan 2018]

    9Be scattering with microscopic wave functions and the CDCC method

    P. Descouvemont · N. Itagaki

    We use microscopic 9Be wave functions defined in a alpha+alpha+n multicluster model to compute 9Be+target scattering cross sections. The parameter sets describing 9Be are generated in the spirit of the Stochastic Variational Method (SVM), and the optimal solution is obtained by superposing Slater determinants and by diagonalizing the Hamiltonian. The 9Be three-body continuum is approximated by square-integral wave functions. The 9Be microscopic wave functions are then used in a Continuum Discretized Coupled Channel (CDCC) calculation of 9Be+208Pb and of 9Be+27Al elastic scattering. Without any parameter fitting, we obtain a fair agreement with experiment. For a heavy target, the influence of 9Be breakup is important, while it is weaker for light targets. This result confirms previous non-microscopic CDCC calculations. One of the main advantages of the microscopic CDCC is that it is based on nucleon-target interactions only; there is no adjustable parameter. The present work represents a first step towards more ambitious calculations involving heavier Be isotopes.

    Comments:
    Phys. Rev. C in press
    Subjects:
    Nuclear Theory (nucl-th); Nuclear Experiment (nucl-ex)
    arXiv:
    1801.02739 [pdf]
    PRC(2018)·17 citations
  2. 02

    [Submitted on 9 Jan 2018]

    Three-neutron resonance study using transition operators

    A. Deltuva

    Existing bound-state type calculations of three-neutron resonances yield contradicting results. A direct study of the three-neutron continuum using rigorous scattering equations with realistic potentials and search for possible resonances is aimed. Faddeev-type integral equations for three-neutron transition operators are solved in the momentum-space partial-wave framework. The evolution of resonances is studied by enhancing the strength of the two-neutron interaction in partial waves with nonzero orbital momentum. Calculated three-neutron transition operators exhibit resonant behavior for sufficiently large enhancement factors; pole trajectories in the complex-energy energy plane are extracted from their energy dependence. However, the resonant behavior completely disappears for the physical interaction strength. There are no physically observable three-neutron resonant states consistent with presently accepted interaction models.

    Comments:
    6 pages, 6 figures (one figure and discussion added)
    Subjects:
    Nuclear Theory (nucl-th); Nuclear Experiment (nucl-ex)
    arXiv:
    1801.02919 [pdf]
    PRC(2018)·24 citations
  3. 03

    [Submitted on 8 Jan 2018] (cross-list from hep-ph)

    Simplicity from Recoil: The Three-Loop Soft Function and Factorization for the Energy-Energy Correlation

    Ian Moult🇺🇸 · Hua Xing Zhu🇨🇳

    We derive an operator based factorization theorem for the energy-energy correlation (EEC) observable in the back-to-back region, allowing the cross section to be written as a convolution of hard, jet and soft functions. We prove the equivalence of the soft functions for the EEC and color singlet transverse-momentum resummation to all-loop order, and give their analytic result to three-loops. Large logarithms appearing in the perturbative expansion of the EEC can be resummed to all orders using renormalization group evolution. We give analytic results for all required anomalous dimensions to three-loop order, providing the first example of a transverse-momentum (recoil) sensitive event shape whose anomalous dimensions are known at this order. The EEC can now be computed to next-to-next-to-next-to-leading logarithm matched to next-to-next-to-leading order, making it a prime candidate for precision QCD studies and extractions of the strong coupling constant. We anticipate that our factorization theorem will also be crucial for understanding non-perturbative power corrections for the EEC, and their relationship to those appearing in other observables.

    Comments:
    32 pages, 3 figures v2. Updated several typos in the text. v3. Final published version. Minor typos updated
    Subjects:
    High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Theory (hep-th); Nuclear Theory (nucl-th)
    arXiv:
    1801.02627 [pdf]
    JHEP(2018)·150 citations
  4. 04

    [Submitted on 8 Jan 2018] (cross-list from hep-ph)

    Doubly charmed baryon production in heavy ion collisions

    Xiaojun Yao🇺🇸 · Berndt Müller🇺🇸

    We give an estimate of production rate and transverse momentum spectra in relativistic heavy ion collisions. We use Boltzmann transport equations to describe the dynamical evolution of charm quarks and diquarks inside quark-gluon plasma. In-medium formation and dissociation rates of charm diquarks are calculated from potential non-relativistic QCD for the diquark sector. We solve the transport equations by Monte Carlo simulations. For TeV Pb-Pb collisions with centrality, the number of produced in the transverse momentum range GeV and rapidity from to is roughly per collision. We repeat the calculation with a melting temperature MeV above which no diquarks can be formed. The number of produced in the same kinematic region is about per collision. We discuss how to study diquarks at finite temperature on a lattice and construct the anti-triplet free energy in a gauge invariant but path dependent way. We also comment on extensions of the calculation to other doubly heavy baryons and doubly heavy tetraquarks and the feasibility of experimental measurements.

    Comments:
    9 pages, 3 figures, add a discussion of productions of other doubly heavy baryons and doubly heavy tetraquarks; add a discussion on diquark free energy on the lattice; add a comment on experimental feasibility; published version
    Subjects:
    High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Experiment (hep-ex); Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
    arXiv:
    1801.02652 [pdf]
    PRD(2018)·57 citations

Affiliations

first authorsco-authorsvia INSPIRE