Wed·Aug 12, 2020Wednesday·August 12, 2020

1. 01*

   Global trends of nuclear $d_{5/2}^{2,3,4}$ configurations: Application of a simple effective-interaction model

   M. Wiedeking🇿🇦 · A.O. Macchiavelli🇺🇸

   With new experimental information on nuclei far from stability being available, a systematic investigation of excitation energies and electromagnetic properties along the $N=10,11,12$ isotones and $Z=10,11,12$ isotopes is presented. The experimental data are discussed in the context of the appearance and disappearance of shell closures at $N=Z=8,14,16,20$, and compared to an effective-interaction approach applied to neutrons and protons in $d_{5/2}^{2,3,4}$ configurations. In spite of its simplicity the model is able to explain the observed properties.

   nucl-exnucl-thEPJA(2020)·1 citation
2. 02*

   Probing the QCD phase structure using event-by-event fluctuations

   Tapan K. Nayak🇮🇳

   Heavy-ion collisions at relativistic energies probe matter at extreme conditions of temperatures and energy densities. The study of event-by-event fluctuations of experimental observables is crucial to probe the QCD phase transition, locate the critical point, and learn about the associated critical phenomena. At the critical point, all thermodynamic quantities behave anomalously. Fluctuation measurements provide access to thermodynamic response functions. We discuss the methods for obtaining the isothermal compressibility using particle multiplicity fluctuation, and specific heat using fluctuations in mean transverse momentum, temperature, and energy. Lattice QCD calculations have predicted non-monotonic behavior in the higher-order cumulants of conserved quantities at the critical point. Fluctuations in the multiplicity of charged to neutral particles have been measured to understand the formation of domains of disoriented chiral condensates. We review the recent fluctuation results as a function of collision centrality and energy from experiments at SPS, RHIC, and LHC. In addition, we propose to map the temperature fluctuations in eta-phi plane to probe local fluctuations of temperature and energy density.

   nucl-exhep-exhep-phnucl-thJ.Phys.Conf.Ser.(2020)·10 citations
3. 03*

   Centrality dependence of J/$\psi$ and $\psi$(2S) production and nuclear modification in p-Pb collisions at $\sqrt{s_{\mathrm{NN}}}=$ 8.16 TeV

   ALICE Collaboration

   The inclusive production of the J/$\psi$ and $\psi$(2S) charmonium states is studied as a function of centrality in p-Pb collisions at a centre-of-mass energy per nucleon pair $\sqrt{s_{\mathrm{NN}}}=8.16$ TeV at the LHC. The measurement is performed in the dimuon decay channel with the ALICE apparatus in the centre-of-mass rapidity intervals $-4.46<y_{\mathrm{cms}}<-2.96$ (Pb-going direction) and $2.03<y_{\mathrm{cms}}<3.53$ (p-going direction), down to zero transverse momentum ($p_{\mathrm{T}}$). The J/$\psi$ and $\psi$(2S) production cross sections are evaluated as a function of the collision centrality, estimated through the energy deposited in the zero degree calorimeter located in the Pb-going direction. The $p_{\mathrm{T}}$-differential J/$\psi$ production cross section is measured at backward and forward rapidity for several centrality classes, together with the corresponding average $⟨p_{\mathrm{T}}⟩$ and $⟨p_{\mathrm{T}}^2⟩$ values. The nuclear effects affecting the production of both charmonium states are studied using the nuclear modification factor. In the p-going direction, a suppression of the production of both charmonium states is observed, which seems to increase from peripheral to central collisions. In the Pb-going direction, however, the centrality dependence is different for the two states: the nuclear modification factor of the J/$\psi$ increases from below unity in peripheral collisions to above unity in central collisions, while for the $\psi$(2S) it stays below or consistent with unity for all centralities with no significant centrality dependence. The results are compared with measurements in p-Pb collisions at $\sqrt{s_{\mathrm{NN}}}=5.02$ TeV and no significant dependence on the energy of the collision is observed. Finally, the results are compared with theoretical models implementing various nuclear matter effects.

   nucl-exhep-exJHEP(2021)·22 citations
4. 04*

   Shape Coexistence at Zero Spin in 64Ni Driven by the Monopole Tensor Interaction

   N. Mărginean · D. Little · Y. Tsunoda · S. Leoni · R. V. F. Janssens · B. Fornal · T. Otsuka · C. Michelagnoli · L. Stan · F. C. L. Crespi · C. Costache · R. Lica and 66 other authors

   The low-spin structure of the semimagic 64Ni nucleus has been considerably expanded: combining four experiments, several 0+ and 2+ excited states were identified below 4.5 MeV, and their properties established. The Monte Carlo shell model accounts for the results and unveils an unexpectedly complex landscape of coexisting shapes: a prolate 0+ excitation is located at a surprisingly high energy (3463 keV), with a collective 2+ state 286 keV above it, the first such observation in Ni isotopes. The evolution in excitation energy of the prolate minimum across the neutron N = 40 subshell gap highlights the impact of the monopole interaction and its variation in strength with N.

   nucl-exnucl-thPRL(2020)·38 citations
5. 05*

   Study of ground state properties of carbon isotopes with deformed relativistic Hartree-Bogoliubov theory in continuum

   Xiang-Xiang Sun🇨🇳 · Jie Zhao · Shan-Gui Zhou🇨🇳

   Ground state properties of carbon isotopes, including root-mean-square radii, neutron separation energies, single particle spectra, and shapes are systematically studied with the deformed relativistic Hartree-Bogoliubov theory in continuum. The calculations with the effective interaction PK1 reproduce the available data reasonably well. The shell evolution in this isotopic chain is investigated by examining the single particle spectra. The inversion of neutron orbitals $\nu 2s_{1/2}$ and $\nu 1d_{5/2}$ compared with the order of neutron orbitals in stable nuclei is revealed in ${}^{15-20,22}\mathrm{C}$ when these nuclei are constrained to spherical shape. Neutron halos in ${}^{15,19,22}$C are studied in detail and their halo structures are mainly caused by the inversion of ($\nu 2s_{1/2},\nu 1d_{5/2}$) and deformation effects. In particular, ${}^{15}$C and ${}^{22}$C are deformed halo nuclei with shape decoupling effects in ground states.

   ↳ nucl-thnucl-exNPA(2020)·70 citations

* Reconstructed cohort: no mailing for this day survives in the archive. Papers are grouped by their submission times and arXiv's announcement cut-off, assuming announcement without delay; positions follow identifier order. Validated at ~91% exact-day agreement against the archived era.