Nuclear Theory·nucl-th

Wednesday·September 16, 2015

8 papers—5 primary·3 cross-listed

01
Probing mixed-spin pairing in heavy nuclei
Brendan Bulthuis · Alexandros Gezerlis
The nature of the nuclear pairing condensate is an active topic of investigation, especially as regards its neutron-proton versus identical-particle character, which manifests as the difference between spin-singlet and spin-triplet pairing. In this work, we probe the recently proposed mixed-spin pairing condensates, using a phenomenological Hamiltonian and Hartree-Fock-Bogoliubov theory along with the gradient method. In addition to improving the solution of the many-body problem, we have calculated a series of physical quantities and examined the robustness of the mixed-spin pairing state as the input Hamiltonian is modified. Overall, we find that even though the mixed-spin correlation energy is suppressed in comparison to earlier work, the new pairing behavior persists. We also discuss the possibility of directly probing the mixed-spin pairing phase.
nucl-thcond-mat.supr-conPRC(2016)·14 citations
02
(Anti-)strangeness production in heavy-ion collisions
Pierre Moreau🇩🇪 · Feng Li🇺🇸 · Che-Ming Ko🇺🇸 · Wolfgang Cassing🇩🇪 · Elena Bratkovskaya🇩🇪
The production and dynamics of strange and antistrange hadrons in heavy-ion reactions from $s_{N N} \approx$ 3 GeV to 200 GeV is analyzed within the Parton-Hadron-String-Dynamics (PHSD) transport model. The PHSD results for strange baryon and antibaryon production are roughly consistent with the experimental data starting from upper SPS energies. Nevertheless, hadronic final state flavor-exchange reactions are important for the actual abundances, in particular at large rapidities where hadronic dynamics, parton fragmentation and string decay dominate. A striking disagreement between the PHSD results and the available data persists, however, for bombarding energies below $s_{N N} \approx$ 8 GeV where the strangeness production is significantly underestimated as in earlier HSD studies. This finding implies that the strangeness enhancement seen experimentally at FAIR/NICA energies cannot be attributed to a deconfinement phase transition or crossover but probably involves the approximate restoration of chiral symmetry in the hadronic phase.
nucl-thhep-phJ.Phys.Conf.Ser.(2016)·5 citations
03
Microscopic coupled-channel calculations of nucleus-nucleus scattering including chiral three-nucleon-force effects
Kosho Minomo · Michio Kohno · Kazuyuki Ogata
We analyze $^{16}$ O- $^{16}$ O and $^{12}$ C- $^{12}$ C scattering with the microscopic coupled-channels method and investigate the coupled-channels and three-nucleon-force (3NF) effects on elastic and inelastic cross sections. In the microscopic coupled-channels calculation, the Melbourne g-matrix interaction modified according to the chiral 3NF effects is used. It is found that the coupled-channels and 3NF effects additively change both the elastic and inelastic cross sections. As a result, the coupled-channels calculation including the 3NF effects significantly improves the agreement between the theoretical results and the experimental data. The incident-energy dependence of the coupled-channels and 3NF effects is also discussed.
nucl-thPRC(2016)·20 citations
04
Beta-decay study within multi-reference density functional theory and beyond
M. Konieczka🇵🇱 · P. Baczyk🇵🇱 · W. Satula🇵🇱
Pioneering study of Gamow-Teller (GT) and Fermi matrix elements (MEs) using no-core-configuration-interaction formalism rooted in multi-reference density functional theory is presented. After successful test performed for 6He -> 6Li beta-decay, the model is applied to compute MEs in the sd- and pf-shell T=1/2 mirror nuclei. The calculated GT MEs and the isospin-symmetry-breaking corrections to the Fermi branch are found to be in a very good agreement with shell-model predictions in spite of fundamental differences between these models concerning model space, treatment of correlations or inclusion of a core. This result indirectly supports the two-body current based scenarios behind the quenching of axial-vector coupling constant.
nucl-thnucl-exPRC(2016)·23 citations
05
One-nucleon transfer reactions and the optical potential
F.M. Nunes🇺🇸 · A. Lovell🇺🇸 · A. Ross🇺🇸 · L.J. Titus🇺🇸 · R.J. Charity🇺🇸 · W.H. Dickhoff🇺🇸 · M.H. Mahzoon🇺🇸 · J. Sarich🇺🇸 · S. M. Wild🇺🇸
We provide a summary of new developments in the area of direct reaction theory with a particular focus on one-nucleon transfer reactions. We provide a status of the methods available for describing (d,p) reactions. We discuss the effects of nonlocality in the optical potential in transfer reactions. The results of a purely phenomenological potential and the optical potential obtained from the dispersive optical model are compared; both point toward the importance of including nonlocality in transfer reactions explicitly. Given the large ambiguities associated with optical potentials, we discuss some new developments toward the quantification of this uncertainty. We conclude with some general comments and a brief account of new advances that are in the pipeline.
nucl-th0 citations
06
Energy dependence of the ridge in high multiplicity proton-proton collisions
Kevin Dusling🇺🇸 · Prithwish Tribedy🇺🇸 · Raju Venugopalan🇺🇸
We demonstrate that the recent measurement of azimuthally collimated, long range rapidity ("ridge") correlations in $s = 13$ TeV proton-proton (p+p) collisions by the ATLAS collaboration at the LHC are in agreement with expectations from the color glass condensate effective theory of high energy QCD. The observation that the integrated near side yield as a function of multiplicity is independent of collision energy is a natural consequence of the fact that multiparticle production is driven by a single semi-hard saturation scale in the color glass condensate framework. We argue further that the azimuthal structure of these recent ATLAS ridge measurements strongly constrain hydrodynamic interpretations of such correlations in high multiplicity p+p collisions.
↳ hep-phhep-exnucl-exnucl-thPRD(2016)·37 citations
07
Initial state in heavy ion collisions
T. Lappi🇫🇮
We briefly review advances in understanding the initial stages of a heavy ion collision. In particular the focus is on moving from parametrizing the initial state to calculating its properties from QCD, consistently with the description of hard probes and dilute-dense scattering experiments. Modeling the event-by-event fluctuating nuclear geometry in initial state calculations has significantly improved in recent years. We also discuss prospects of directly seeing effects of particle correlations created in the initial state in the experimental observables.
↳ hep-phnucl-thNucl.Part.Phys.Proc.(2016)·9 citations
08
Heavy-flavor transport
Andrea Beraudo🇮🇹
The formation of a hot deconfined medium (Quark-Gluon Plasma) in high-energy nuclear collisions affects heavy-flavor observables. In the low/moderate-pT range transport calculations allow one to simulate the propagation of heavy quarks in the plasma and to evaluate the effect of the medium on the final hadronic spectra: results obtained with transport coefficients arising from different theoretical approaches can be compared to experimental data. Finally, a discussion of possible effects on heavy-flavor observables due to the possible formation of a hot-medium in small systems (like in p-A collisions) is presented.
↳ hep-phhep-exnucl-thJ.Phys.Conf.Ser.(2016)·1 citation

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first authorsco-authorsvia INSPIRE