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Nuclear Theory·nucl-th

Friday·March 20, 2020

9 papers—5 primary·4 cross-listed

All9Primary5Cross-lists4
  1. 06

    One-meson-loop NJL model: Effect of collective and noncollective excitations on the quark condensate at finite temperature

    Renan Câmara Pereira🇵🇹 · Pedro Costa🇵🇹

    We explore the effect of including quantum fluctuations in the two flavor NambuJona-Lasinio model at finite temperature. This is accomplished, in a symmetry preserving way, by including collective and noncollective modes in the one-meson-loop gap equation which originate from poles and branch cuts in the complex plane, respectively. The inclusion of a boson cutoff, , is necessary to regularize the meson-loop momenta. This new parameter is used to study the influence of going beyond the usual mean field approximation in the quark condensate. As the temperature increases, chiral symmetry tends to get restored, the collective modes melt and only noncollective modes contribute to the quark condensate. With the inclusion of such modes, the quark condensate at finite temperature has a different behavior than at mean field level that will be explored.

    ↳ hep-phnucl-thPRD(2020)·7 citations
  2. 07

    Complete flavor decomposition of the spin and momentum fraction of the proton using lattice QCD simulations at physical pion mass

    C. Alexandrou (Univ. of Cyprus & The Cyprus Inst.)🇨🇾 · S. Bacchio (The Cyprus Inst.)🇨🇾 · M. Constantinou (Temple Univ.)🇺🇸 · J. Finkenrath (The Cyprus Inst.)🇨🇾 · K. Hadjiyiannakou (Univ. of Cyprus & The Cyprus Inst.)🇨🇾 · K. Jansen (DESY-Zeuthen)🇩🇪 · G. Koutsou (The Cyprus Inst.)🇨🇾 · H. Panagopoulos (Univ. of Cyprus)🇨🇾 · G. Spanoudes (Univ. of Cyprus)🇨🇾

    We evaluate the gluon and quark contributions to the spin of the proton using an ensemble of gauge configuration generated at physical pion mass. We compute all valence and sea quark contributions to high accuracy. We perform a non-perturbative renormalization for both quark and gluon matrix elements. We find that the contribution of the up, down, strange and charm quarks to the proton intrinsic spin is and to the total spin . The gluon contribution to the spin is yielding confirming the spin sum. The momentum fraction carried by quarks in the proton is found to be and by gluons , the sum of which gives confirming the momentum sum rule. All scale and scheme dependent quantities are given in the scheme at 2 GeV.

    ↳ hep-lathep-exhep-phnucl-ex+1PRD(2020)·191 citations
  3. 08

    Refined scenario of the collinear cluster tri-partition mode with the greatest yield

    Yu.V. Pyatkov · D. V. Kamanin · Yu. M. Tchuvil'sky · A. A. Alexandrov · I. A. Alexandrova · Z. I. Goryainova · V. Malaza · E. A. Kuznetsova · A. O. Strekalovsky · O. V. Strekalovsky · Sh. Wyngaardt · V. E. Zhuchko

    In our previous publications we discussed various manifestations of a new decay channel of the low excited heavy nuclei called collinear cluster tri-partition (CCT). The most populated CCT mode was revealed in the mass correlation distribution of fission fragments (FFs) as a local region ("bump") of increased yields below the loci linked to the conventional binary fission. The bump was dubbed "Ni-bump" because it is centered at the masses associated with the magic isotopes of Ni. Intriguing features of the CCT, especially high collinearity of the CCT partners and relatively high probability comparable with that typical for conventional ternary fission, have caused rather wide discussion. In the majority of dedicated publications, the FFs partitions from the Ni-bump have been analyzed from the different points of view. In our publications, we have underlined that Ni-bump manifests itself at the detectable level only in the spectrometer arm that faces the source backing. So far, this fact has been left beyond the scope of all known theoretical considerations, while the backing likely plays a crucial role in the observation of the CCT experimental pattern.

    ↳ nucl-exnucl-th0 citations
  4. 09

    The Boltzmann-radiation-hydrodynamics Simulations of Core-collapse Supernovae with Different Equations of State: the Role of Nuclear Composition and the Behavior of Neutrinos

    Akira Harada · Hiroki Nagakura · Wakana Iwakami · Hirotada Okawa · Shun Furusawa · Kohsuke Sumiyoshi · Hideo Matsufuru · Shoichi Yamada

    Using the Boltzmann-radiation-hydrodynamics code, which solves the Boltzmann equation for neutrino transport, we present the results of the simulations with the nuclear equations of state (EOSs) of Lattimer and Swesty (LS) and Furusawa and Shen (FS). We extend the simulation time of the LS model and conduct thorough investigations, though our previous paper briefly reported some of the results. Only the LS model shows the shock revival. This seems to originate from the nuclear composition: the different nuclear composition results in the different energy loss by photodissociation and hence the different strength of the prompt convection and the later neutrino-driven convection. The protoneutron star seen in the FS model is more compact than that in the LS model because the existence of multinuclear species softens the EOS. For the behavior of neutrinos, we examined the flux and the Eddington tensor of neutrinos. In the optically thick region, the diffusion of neutrinos and the dragging by the motion of matter determine the flux. In the optically thin region, the free-streaming determines it. The Eddington tensor is compared with that obtained from the M1-closure relation. The M1-closure scheme overestimates the contribution from the velocity-dependent terms in the semitransparent region.

    ↳ astro-ph.HEastro-ph.SRnucl-thApJ(2020)·36 citations

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first authorsco-authorsvia INSPIRE