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Nuclear Theory·nucl-th

Tuesday·January 12, 2016

14 papers—9 primary·5 cross-listed

All14Primary9Cross-lists5
  1. 10

    Cigar-shaped quarkonia under strong magnetic field

    Kei Suzuki🇯🇵 · Tetsuya Yoshida🇯🇵

    Heavy quarkonia in a homogeneous magnetic field are analyzed by using a potential model with constituent quarks. To obtain anisotropic wave functions and corresponding eigenvalues, the cylindrical Gaussian expansion method is applied, where the anisotropic wave functions are expanded by a Gaussian basis in the cylindrical coordinates. Deformation of the wave functions and the mass shifts of the -wave heavy quarkonia (, , , and bottomonia) are examined for the wide range of external magnetic field. The spatial structure of the wave functions changes drastically as adjacent energy levels cross each other. Possible observables in heavy-ion collision experiments and future lattice QCD simulations are also discussed.

    ↳ hep-phhep-latnucl-exnucl-thPRD(2016)·32 citations
  2. 11

    Classic Calculations of Static Properties of the Nucleons reexamined

    N. F. Nasrallah🇱🇧

    Classic calculations of the magnetic moments mu_p and mu_n of the nucleons using the traditional exponential kernel show instability with respect to variations of the Borel mass as well as arbitrariness with respect to the choice of the onset of perturbative QCD. The use of a polynomial kernel, the coefficients of which are determined by the masses of the nucleon resonances stabilizes the calculation and provides much better damping of the unknown contribution of the nucleon continuum. The method is also applied to the evaluation of the coupling gA of proton to the axial current and to the strong part of the neutron-proton mass difference Delta M_np. All these quantities depend sensitively on the value of the 4-quark condensate < 0 | qqqq | 0 > and the value < 0 | qqqq | 0 > ~ 1.5< 0 | qq | 0 >^2 reproduces the experimental results.

    ↳ hep-phnucl-thPRC(2016)·0 citations
  3. 12

    Drag and Diffusion of Heavy Quarks in a hot and anisotropic QCD medium

    P. K. Srivastava🇮🇳 · Binoy Krishna Patra🇮🇳

    The propagation of heavy quarks (HQs) in a medium was quite often modeled by the Fokker-Plank (FP) equation. Since the transport coefficients, related to drag and diffusion processes are the main ingredients in the FP equation, the evolution of HQs is thus effectively controlled by them. At the initial stage of the relativistic heavy ion collisions, asymptotic weak-coupling causes the free-streaming motions of partons in the beam direction and the expansion in transverse directions are almost frozen, hence an anisotropy in the momentum space sets in. Since HQs are too produced in the same time therefore the study of the effect of momentum anisotropy on the drag and diffusion coefficients becomes advertently desirable. In this article we have thus studied the drag and diffusion of HQs in the anisotropic medium and found that the presence of the anisotropy reduces both drag and diffusion coefficients. In addition, the anisotropy introduces an angular dependence to both the drag and diffusion coefficients, as a result both coefficients get inflated when the partons are moving transverse to the direction of anisotropy than parallel to the direction of anisotropy.

    ↳ hep-phnucl-thEPJA(2017)·15 citations
  4. 13

    Fast Dynamical Evolution of Hadron Resonance Gas via Hagedorn States

    M. Beitel🇩🇪 · C. Greiner🇩🇪 · H. Stoecker🇩🇪

    Hagedorn states are the key to understand how all hadrons observed in high energy heavy ion collisions seem to reach thermal equilibrium so quickly. An assembly of Hagedorn states is formed in elementary hadronic or heavy ion collisions at hadronization. Microscopic simulations within the transport model UrQMD allow to study the time evolution of such a pure non-equilibrated Hagedorn state gas towards a thermally equilibrated Hadron Resonance Gas by using dynamics, which unlike strings, fully respect detailed balance. Propagation, repopulation, rescatterings and decays of Hagedorn states provide the yields of all hadrons up to a mass of m=2.5 GeV. Ratios of feed down corrected hadron multiplicities are compared to corresponding experimental data from the ALICE collaboration at LHC. The quick thermalization within t=1-2 fmo̧f the emerging Hadron Resonance Gas exposes Hagedorn states as a tool to understand hadronization.

    ↳ hep-phnucl-thPRC(2016)·18 citations
  5. 14

    Nucleon Resonance Structure Studies Via Exclusive KY Electroproduction

    Daniel S. Carman (for the CLAS Collaboration)🇺🇸

    Studying the structure of excited nucleon states employing the electroproduction of exclusive reactions is an important avenue for exploring the nature of the non-perturbative strong interaction. The electrocouplings of states in the mass range below 1.8~GeV have been determined from analyses of CLAS , , and data. This work has made it clear that consistent results from independent analyses of several exclusive channels with different couplings and non-resonant backgrounds but the same electro-excitation amplitudes, is essential to have confidence in the extracted results. In terms of hadronic coupling, many high-lying states preferentially decay through the channel instead of . Data from the channels will therefore be critical to provide an independent analysis to compare the extracted electrocouplings for the high-lying states against those determined from the and channels. A program to study excited state structure in both non-strange and strange exclusive electroproduction channels using CLAS12 will measure differential cross sections and polarization observables to be used as input to extract the electrocoupling amplitudes for the most prominent states in the range of invariant energy up 3~GeV in the virtually unexplored domain of momentum transfers up to 12~GeV.

    ↳ nucl-exnucl-thFew Body Syst.(2016)·10 citations

Affiliations

first authorsco-authorsvia INSPIRE