Thu·Feb 4, 2021Thursday·February 4, 2021

1. 01*

   Proton-neutron pairing correlations in the self-conjugate nucleus ${}^{42}$Sc

   Agota Koszorus🇬🇧 · Liam Vormawah🇬🇧 · Randolf Beerwerth🇩🇪 · Mark Bissell🇬🇧 · Paul Campbell🇬🇧 · Bradley Cheal🇬🇧 · Charlie Devlin🇬🇧 · Tommi Eronen🇫🇮 · Stephan Fritzsche🇩🇪 · Sarina Geldhof🇫🇮 · Hanne Heylen🇨🇭 · Jason Holt🇨🇦 and 7 other authors

   Collinear laser spectroscopy of the $N=Z=21$ self-conjugate nucleus ${}^{42}$Sc has been performed at the JYFL IGISOL IV facility in order to determine the change in nuclear mean-square charge radius between the $I^{\pi }=0^{+}$ ground state and the $I^{\pi }=7^{+}$ isomer via the measurement of the ${}^{42\mathrm{g},42\mathrm{m}}$Sc isomer shift. New multi-configurational Dirac-Fock calculations for the atomic mass shift and field shift factors have enabled a recalibration of the charge radii of the ${}^{42-46}$Sc isotopes which were measured previously. While consistent with the treatment of proton-neutron, proton-proton and neutron-neutron pairing on an equal footing, the reduction in size for the isomer is observed to be of a significantly larger magnitude than that expected from both shell model and ab-initio calculations.

   nucl-exPLB(2021)·10 citations
2. 02*

   Insights into the Emergence of Mass from Studies of Pion and Kaon Structure

   Craig D. Roberts🇨🇳 · David G. Richards🇺🇸 · Tanja Horn🇺🇸 · Lei Chang🇨🇳

   There are two mass generating mechanisms in the standard model of particle physics (SM). One is related to the Higgs boson and fairly well understood. The other is embedded in quantum chromodynamics (QCD), the SM's strong interaction piece; and although responsible for emergence of the roughly 1 GeV mass scale that characterises the proton and hence all observable matter, the source and impacts of this emergent hadronic mass (EHM) remain puzzling. As bound states seeded by a valence-quark and -antiquark, pseudoscalar mesons present a simpler problem in quantum field theory than that associated with the nucleon. Consequently, there is a large array of robust predictions for pion and kaon properties whose empirical validation will provide a clear window onto many effects of both mass generating mechanisms and the constructive interference between them. This has now become significant because new-era experimental facilities, in operation, construction, or planning, are capable of conducting such tests and thereby contributing greatly to resolving the puzzles of EHM. These aspects of experiment, phenomenology, and theory, along with contemporary successes and challenges, are sketched herein, simultaneously highlighting the potential gains that can accrue from a coherent effort aimed at finally reaching an understanding of the character and structure of Nature's Nambu-Goldstone modes.

   ↳ hep-phhep-exhep-latnucl-ex+1PPNP(2021)·214 citations
3. 03*

   Parton collisional effect on the conversion of geometry eccentricities into momentum anisotropies in relativistic heavy-ion collisions

   Long Ma🇨🇳 · Guo-Liang Ma🇨🇳 · Yu-Gang Ma🇨🇳

   We explore parton collisional effects on the conversion of geometry eccentricities into azimuthal anisotropies in Pb+Pb collisions at $\sqrt{s_{NN}}$ = 5.02 TeV using a multi-phase transport model. The initial eccentricity ${\epsilon }_n$ (n = 2,3) and flow harmonics $v_n$ (n = 2,3) are investigated as a function of the number of parton collisions ($N_{coll}$) during the source evolution of partonic phase. It is found that partonic collisions leads to generate elliptic flow $v_2$ and triangular flow $v_3$ in Pb+Pb collisions. On the other hand, partonic collisions also result in an evolution of the eccentricity of geometry. The collisional effect on the flow conversion efficiency is therefore studied. We find that the partons with larger $N_{coll}$ show a lower flow conversion efficiency, which reflect differential behaviors with respect to $N_{coll}$. It provides an additional insight into the dynamics of the space-momentum transformation during the QGP evolution from a transport model point of view.

   ↳ nucl-thhep-phnucl-exPRC(2021)·8 citations
4. 04*

   On the structure of the correlation coefficients S(E_e) and U(E_e) of the neutron beta decay

   A. N. Ivanov🇦🇹 · R. Höllwieser🇩🇪 · N. I. Troitskaya🇦🇹 · M. Wellenzohn🇦🇹 · Ya. A. Berdnikov🇷🇺

   In the standard effective V - A theory of low-energy weak interactions (i.e. in the Standard Model (SM)) we analyze the structure of the correlation coefficients S(E_e) and U(E_e), where E_e is the electron energy. These correlation coefficients were introduced to the electron-energy and angular distribution of the neutron beta decay by Ebel and Feldman ( Nucl. Phys. 4, 213 (1957)) in addition to the set of correlation coefficients proposed by Jackson et al. (Phys. Rev. 106, 517 (1957)). The correlation coefficients $S(E_e)$ and $U(E_e)$ are induced by simultaneous correlations of the neutron and electron spins and electron and antineutrino 3-momenta. These correlation structures do no violate discrete P, C and T symmetries. We analyze the contributions of the radiative corrections of order O(alpha/pi), taken to leading order in the large nucleon mass m_N expansion, and corrections of order O(E_e/m_N), caused by weak magnetism and proton recoil. In addition to the obtained SM corrections we calculate the contributions of interactions beyond the SM (BSM contributions) in terms of the phenomenological coupling constants of BSM interactions by Jackson et al. (Phys. Rev. 106, 517 (1957)) and the second class currents by Weinberg (Phys. Rev. 112, 1375 (1958)).

   ↳ hep-phhep-exnucl-exnucl-thPRC(2021)·3 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.