Mon·Jan 4, 2021Monday·January 4, 2021

1. 01*

   Energy dependent angular distribution of individual $\gamma$-rays in the ${}^{139}$La($n$, $\gamma$)${}^{140}$La* reaction

   T. Okudaira🇯🇵 · S. Endo🇯🇵 · H. Fujioka🇯🇵 · K. Hirota🇯🇵 · K. Ishizaki🇯🇵 · A. Kimura🇯🇵 · M. Kitaguchi🇯🇵 · J. Koga · Y. Niinomi · K. Sakai🇯🇵 · T. Shima🇯🇵 · H. M. Shimizu🇯🇵 and 5 other authors

   Neutron energy-dependent angular distributions were observed for individual $\gamma$-rays from the 0.74 eV p-wave resonance of ${}^{139}$La+$n$ to several lower excited states of ${}^{140}$La. The $\gamma$-ray signals were analyzed in a two dimensional histogram of the $\gamma$-ray energy, measured with distributed germanium detectors, and neutron energy, determined with the time-of-flight of pulsed neutrons, to identify the neutron energy dependence of the angular distribution for each individual $\gamma$-rays. The angular distribution was also found for a photopeak accompanied with a faint p-wave resonance component in the neutron energy spectrum. Our results can be interpreted as interference between s- and p-wave amplitudes which may be used to study discrete symmetries of fundamental interactions.

   nucl-exPRC(2021)·8 citations
2. 02*

   The Mystery of Bloom-Gilman Duality: A Light Front Holographic QCD Perspective

   Aiden B. Sheckler🇺🇸 · Gerald A. Miller🇺🇸

   Light front wave functions motivated by holographic constructions are used to study Bloom-Gilman duality of deep inelastic scattering. Separate expressions for structure functions in terms of quark and hadronic degrees of freedom are presented, with a goal of relating the two expressions. A two-parton model is defined and resonance transition form factors are computed using previously derived light front wave functions. A new form of global duality is derived from the valence quark-number sum rule. Using a complete set of hadronic states is necessary for this new global duality to be achieved. Previous original work does not provide such a set. This is remedied by amending the model to include a longitudinal confining potential, and the resulting complete set is sufficient to carry out the study of Bloom-Gilman duality. Expressions for transition form factors are obtained and all are shown to fall asymptotically as 1/Q2. The Feynman mechanism dominates the asymptotic behavior of the model. These transition form factors are used to assess the validity of the global and local duality sum rules, with the result that both neither are satisfied. Evaluations of the hadronic expression for q(x,Q2) provide more details about this lack. This result shows that the observed validity of both global and local forms of duality for deep inelastic scattering must be related to a feature of QCD that is deeper than completeness. Our simple present model suggests a prediction that Bloom-Gilman duality would not be observed if deep inelastic scattering experiments were to be made on the pion. The underlying origin of the duality phenomenon in deep inelastic scattering is deeply buried within the confinement aspects of QCD, and remains a mystery.

   ↳ hep-phnucl-exnucl-thPRD(2021)·7 citations
3. 03*

   A matter of shape: seeing the deformation of atomic nuclei at high-energy colliders

   Giuliano Giacalone🇫🇷

   This work establishes a deep connection between two seemingly distant branches of nuclear physics: nuclear structure and relativistic heavy-ion collisions. At the heart of this connection is the recent discovery made at particle colliders that the elliptic flow of outgoing hadrons in central nucleus-nucleus collisions is strongly impacted by the quadrupole deformation of the colliding nuclear species. I review the physics of the soft sector of relativistic heavy-ion collisions, and I explain that the interpretation of elliptic flow data in central ${}^{197}$Au+${}^{197}$Au, ${}^{238}$U+${}^{238}$U, and ${}^{129}$Xe+${}^{129}$Xe collisions requires a deep understanding the structure of these ions. Subsequently, I introduce a technique that permits one to isolate collision configurations in which the deformed shapes of the colliding nuclei maximally break rotational (azimuthal) symmetry in the interaction region. This allows me to construct observables that possess an unparalleled sensitivity to the quadrupole deformation of the colliding ions, and thus to conclude that nuclear experiments at high energy can be used to place new quantitative constraints on the deformation of atomic nuclei. I emphasize the great opportunities offered by potential collider experiments aimed at the systematic study of nuclear deformation across the valley of stability.

   ↳ nucl-thhep-exhep-phnucl-ex24 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.