Thu·Apr 5, 2018Thursday·April 5, 2018

1. 01*

   Gamma-widths, lifetimes and fluctuations in the nuclear quasi-continuum

   M.Guttormsen🇳🇴 · A. C. Larsen🇳🇴 · J. E. Midtbø🇳🇴 · L. Crespo Campo🇳🇴 · A. Görgen🇳🇴 · V. W. Ingeberg🇳🇴 · T. Renstrøm🇳🇴 · S. Siem🇳🇴 · G. M. Tveten🇳🇴 · F. Zeiser🇳🇴 · L. E. Kirsch🇺🇸

   Statistical $\gamma$-decay from highly excited states is determined by the nuclear level density (NLD) and the $\gamma$-ray strength function ($\gamma$SF). These average quantities have been measured for several nuclei using the Oslo method. For the first time, we exploit the NLD and $\gamma$SF to evaluate the $\gamma$-width in the energy region below the neutron binding energy, often called the quasi-continuum region. The lifetimes of states in the quasi-continuum are important benchmarks for a theoretical description of nuclear structure and dynamics at high temperature. The lifetimes may also have impact on reaction rates for the rapid neutron-capture process, now demonstrated to take place in neutron star mergers.

   nucl-exEPJ Web Conf.(2018)·0 citations
2. 02*

   First direct lattice-QCD calculation of the $x$-dependence of the pion parton distribution function

   Jian-Hui Zhang🇩🇪 · Jiunn-Wei Chen🇹🇼 · Luchang Jin🇺🇸 · Huey-Wen Lin🇺🇸 · Andreas Schäfer🇩🇪 · Yong Zhao🇺🇸

   We present the first direct lattice-QCD calculation of the Bjorken-$x$ dependence of the valence quark distribution of the pion. Using large-momentum effective theory (LaMET), we calculate the boosted pion state with long Wilson link operators. After implementing the one-loop matching and meson mass corrections, our result at $m_{\pi }\approx 310$ MeV is in agreement with those extracted from experimental data as well as from Dyson-Schwinger equation in small $x$ region, but a sizeable discrepancy in the large $x$ region. This discrepancy provides a nice opportunity to systematically study and disentangle the artifacts in the LaMET approach, which will eventually help to discern various existing analyses in the literature.

   ↳ hep-lathep-exhep-phnucl-ex+1PRD(2019)·170 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.