Fri·Feb 8, 2019Friday·February 8, 2019

1. 01*

   Evidence for coexisting shapes in ${}^{98}$Zr through lifetime measurements

   Purnima Singh🇫🇷 · W. Korten🇫🇷 · T. W. Hagen🇳🇴 · A. Görgen🇳🇴 · L. Grente🇫🇷 · M.-D. Salsac🇫🇷 · F. Farget🇫🇷 · E. Clément🇫🇷 · G. de France🇫🇷 · T. Braunroth🇩🇪 · B. Bruyneel🇫🇷 · I. Celikovic🇫🇷 and 26 other authors

   The lifetimes of first excited 2${}^{+}$, 4${}^{+}$ and 6${}^{+}$ states in ${}^{98}$Zr were measured with the Recoil-Distance Doppler Shift method in an experiment performed at GANIL. Excited states in ${}^{98}$Zr were populated using the fission reaction between a 6.2 MeV/u ${}^{238}$U beam and a ${}^9$Be target. The $\gamma$ rays were detected with the EXOGAM array in correlation with the fission fragments identified in mass and atomic number in the VAMOS++ spectrometer. Our result shows very small B(E2;2${}_1^{+}$ $\to$ 0${}_1^{+}$) value in ${}^{98}$Zr thereby confirming the very sudden onset of collectivity at $N=60$. The experimental results are compared to large-scale Monte Carlo Shell model and beyond mean field calculations. The present results indicate coexistence of two additional deformed shapes in this nucleus along with the spherical ground state.

   nucl-exnucl-thPRL(2018)·60 citations
2. 02*

   $K^0\Lambda$ Photoproduction with Nucleon Resonances

   Sang-Ho Kim🇰🇷 · Hyun-Chul Kim🇰🇷

   We investigate the reaction mechanism of $K^0\Lambda$ photoproduction off the neutron target, i.e., $\gamma n\to K^0\Lambda$, in the range of $W\approx 1.6-2.2$ GeV. We employ an effective Lagrangian method at the tree-level Born approximation combining with a Regge approach. As a background, the $K^{\ast }$-Reggeon trajectory is taken into account in the $t$ channel and $\Lambda$ and $\Sigma$ hyperons in the $u$-channel Feynman diagram. In addition, the role of various nucleon resonances listed in the Particle Data Group (PDG) is carefully scrutinized in the $s$ channel where the resonance parameters are extracted from the experimental data and constituent quark model. We present our numerical results of the total and differential cross sections and compare them with the recent CLAS data. The effect of the narrow nucleon resonance $N(1685,1/2^{+})$ on cross sections is studied in detail and it turns out that its existence is essential in $K^0\Lambda$ photoproduction to reproduce the CLAS data.

   ↳ hep-phhep-exnucl-exnucl-thJPS Conf.Proc.(2019)·0 citations
3. 03*

   Relation between exponential behavior and energy denominators -- Weak Coupling Limit

   Levering Wolfe🇺🇸 · Larry Zamick🇺🇸

   We show some interesting properties of tridiagonal and pentadiagonal matrices in the weak coupling limits. In the former case of this limit the ground state wave function amplitudes are identical to the Taylor expansion coefficients of the exponential function e${}^{(-v/E)}$. With regards to transition rates a dip in the pentadiagonal case which is not present in the tridiagonal case is explained. An intimate connection between energy denominators and exponential behavior is demonstrated.

   ↳ quant-phnucl-exnucl-thIJMPE(2019)·4 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.