Wed·Jan 22, 2025Wednesday·January 22, 2025

1. 01*

   Neutron correlations and clustering in neutron-rich nuclear systems

   Zaihong Yang🇨🇳 · Yuki Kubota🇯🇵

   In this paper, we will briefly review the recent progress on neutron correlations and clustering in neutron-rich nuclei from quasi-free scattering experiments. The quasi-free ($p$, $pn$) reaction was measured for Borromean nuclei ${}^{11}$Li, ${}^{14}$Be, and ${}^{17}$B. A surprisingly small $s$-wave component was found for ${}^{17}$B, revealing a weak neutron halo in ${}^{17}$B, and the comparative study of the three nuclei shows the surface localization of dineutron correlation and its universality in Borromean nuclei. The two-neutron emission of ${}^{16}$Be was also studied, finding strong dineutron correlation in ${}^{16}$Be(g.s.) but weak correlation in ${}^{16}$Be($2^{+}$). Two missing-mass measurements using ${}^4$He(${}^8$He, ${}^8$Be) and ${}^8$He($p$, $p\alpha$) reactions provided evidence for the ${}^{4}n$ resonance, but the ${}^{3}n$ resonance was not supported by the recent experiment employing the $t(t{,}^3$He)${}^{3}n$ charge-exchange reaction. The quasi-free $(p,p\alpha )$ reaction has been extended to unstable nuclei, and the recent experiment unravels the $\alpha$-$2n$-$\alpha$ molecule-like cluster structure of ${}^{10}$Be(g.s.).

   nucl-exnucl-thPTEP(2026)·0 citations
2. 02*

   Deeply virtual $\varphi$-meson production near threshold

   Yoshitaka Hatta🇺🇸 · Henry T. Klest🇺🇸 · Kornelija Passek-K.🇭🇷 · Jakob Schoenleber🇺🇸

   We discuss exclusive $\varphi$-meson electroproduction off the proton near threshold within the GPD factorization framework. We propose the `threshold approximation' in which only the leading term of the conformal partial wave expansion of the meson production amplitudes is kept in both the quark and gluon exchange channels. We test the validity of this approximation to next-to-leading order in QCD and demonstrate the strong sensitivity of the cross section to the gluon and strangeness gravitational form factors. We also perform realistic event generator simulations both for Jefferson Lab and EIC kinematics and demonstrate the capabilities of future facilities for measuring near-threshold $\varphi$ electroproduction.

   ↳ hep-phhep-exnucl-exPTEP(2025)·14 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.