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Nuclear Theory·nucl-th

Friday·August 24, 2018

4 papers—2 primary·2 cross-listed

All4Primary2Cross-lists2
  1. 01

    Constraining the density dependence of symmetry energy using mean field models

    Chiranjib Mondal🇮🇳

    The nuclear symmetry energy characterizes the variation of the binding energy as the neutron to proton ratio of nuclear systems (e.g. finite nucleus, neutron star etc.) is varied. The densities associated to these nuclear systems vary over a wide range. Studying density dependence of symmetry energy is thus a major topic of research in nuclear physics. Density dependence of symmetry energy is primarily characterized by three empirical quantities defined for infinite nuclear matter namely, symmetry energy coefficient J, slope parameter L and curvature parameter K_sym ; all of these quantities pertaining to saturation density \rho_0 of infinite nuclear matter. Since nuclear matter is not accessible in laboratories, one needs to find suitable experimental observables to constrain the values of J, L or K_sym. Though, J is quite precisely known from the experimental data on binding energies of nuclei, it is not quite the case for L or K_sym. This problem is addressed in this thesis using mean field models.

    nucl-th0 citations
  2. 02

    Mean field approach to reconstructed neutrino energy distributions in accelerator-based experiments

    Alexis Nikolakopoulos🇧🇪 · Marco Martini🇫🇷 · Magda Ericson🇫🇷 · Nils Van Dessel🇧🇪 · Raúl González-Jiménez🇪🇸 · Natalie Jachowicz🇧🇪

    The reconstruction of the neutrino energy is crucial in oscillation experiments that use interactions with nuclei to detect the neutrino. The common reconstruction procedure is based on the kinematics of the final-state lepton. The interpretation of the reconstructed energy in terms of the real neutrino energy must rely on a model for the neutrino-nucleus interaction. The Relativistic Fermi Gas (RFG) model is frequently used in these analyses. In the Hartree-Fock (HF) model for quasielastic nucleon knockout, the bound nucleon wave functions are obtained using an effective nucleon-nucleon force. The final-state wave function is constructed from continuum states in the same potential which have the correct asymptotic behavior. The Continuum Random Phase Approximation (CRPA) model extends the HF approach taking long range correlations into account in a self-consistent way. Considering only single-nucleon processes, the distributions of reconstructed neutrino energies obtained within the HF-CRPA approach are compared with the results of the RFG, an RPWIA calculation, and the RPA+np-nh model of Martini et al. We find that the distributions of reconstructed energies for a fixed incoming energy in the HF-CRPA display additional strength in the low reconstructed energy tails compared to models without elastic distortion of the outgoing nucleon. This asymmetry redistributes strength from higher to lower values of the reconstructed energy. The mean field description of the nuclear dynamics results in a reshaping of the reconstructed energy distribution that cannot be accounted for in a plane wave impulse approximation model, even by modifying ad hoc parameters such as the binding energy. In particular it is shown that in the RFG calculations there is no value of the binding energy which is able to reproduce the entire T2K oscillated spectrum as calculated in HF-CRPA.

    nucl-thPRC(2018)·17 citations
  3. 03

    A Simultaneous Description of Hadron and Jet Suppression in Heavy Ion Collisions

    Jorge Casalderrey-Solana🇪🇸 · Zachary Hulcher🇬🇧 · Guilherme Milhano🇵🇹 · Daniel Pablos🇨🇦 · Krishna Rajagopal🇺🇸

    We present a global fit to all data on the suppression of high energy jets and high energy hadrons in the most central heavy ion collisions at the LHC for two different collision energies, within a hybrid strong/weak coupling quenching model. Even though the measured suppression factors for hadrons and jets differ significantly from one another and appear to asymptote to different values in the high energy limit, we obtain a simultaneous description of all these data after constraining the value of a single model parameter. We use our model to investigate the origin of the difference between the observed suppression of jets and hadrons and relate it, quantitatively, to the observed modification of the jet fragmentation function in jets that have been modified by passage through the medium produced in heavy ion collisions. In particular, the observed increase in the fraction of hard fragments in medium-modified jets, which indicates that jets with the fewest hardest fragments lose the least energy, corresponds quantitatively to the observed difference between the suppression of hadrons and jets. We argue that a harder fragmentation pattern for jets with a given energy after quenching is a generic feature of any mechanism for the interaction between jets and the medium that they traverse that yields a larger suppression for wider jets. We also compare the results of our global fit to LHC data to measurements of the suppression of high energy hadrons in RHIC collisions, and find that with its parameter chosen to fit the LHC data our model is inconsistent with the RHIC data at the level, suggesting that hard probes interact more strongly with the less hot quark-gluon plasma produced at RHIC.

    ↳ hep-phnucl-exnucl-thPRC(2019)·72 citations
  4. 04

    Strong Isospin Breaking in Heavy-Meson Decay Constants: Employing Borelized QCD Sum Rules in Local-Duality Limit

    Wolfgang Lucha🇦🇹 · Dmitri Melikhov🇦🇹 · Silvano Simula🇮🇹

    Applying the QCD sum-rule machinery in the so-called local-duality shape to heavy-light mesons reveals that, as a consequence of the non-zero mass gap between up and down quarks, the leptonic decay constants of the neutral and charged versions of the and mesons differ by approximately 1 MeV.

    ↳ hep-phhep-latnucl-thEPJ Web Conf.(2018)·1 citation

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