Fri·Mar 5, 2021Friday·March 5, 2021

1. 01*

   Observation of the near-threshold intruder $0^{-}$ resonance in ${}^{12}$Be

   J. Chen🇨🇳 · S. M. Wang🇺🇸 · H. T. Fortune🇺🇸 · J. L. Lou🇨🇳 · Y. L. Ye🇨🇳 · Z. H. Li🇨🇳 · N. Michel🇨🇳 · J. G. Li🇨🇳 · C. X. Yuan🇨🇳 · Y. C. Ge🇨🇳 · Q. T. Li🇨🇳 · H. Hua🇨🇳 and 25 other authors

   A resonant state at $3.21_{-0.04}^{+0.12}$\,MeV, located just above the one-neutron separation threshold, was observed for the first time in ${}^{12}$Be from the ${}^{11}$Be\,$(d,p{)}^{12}$Be one-neutron transfer reaction in inverse kinematics. This state is assigned a spin-parity of $0^{-}$, according to the distorted-wave Born approximation (DWBA) and decay-width analysis. Gamow coupled-channel (GCC) and Gamow shell-model (GSM) calculations show the importance of the continuum-coupling, which dramatically influences the excitation energy and ordering of low-lying states. Various exotic structures associated with cross-shell intruding configurations in ${}^{12}$Be and in its isotonic nucleus ${}^{11}$Li are comparably discussed.

   nucl-exPRC(2021)·19 citations
2. 02*

   New plasma regimes with small ELMs and high confinement at the Joint European Torus

   J. Garcia · E. de la Luna · M. Sertoli · F. Casson · S. Mazzi · Z. Stancar · G. Szepesi · D. Frigione · L. Garzotti · F. Rimini · D. van Eester · P. Lomas and 6 other authors

   New plasma regimes with high confinement, low core impurity accumulation and small Edge localized mode (ELMs) perturbations have been obtained close to ITER conditions in magnetically confined plasmas from the Joint European torus (JET) tokamak. Such regimes are achieved by means of optimized particle fuelling conditions which trigger a self-organize state with a strong increase in rotation and ion temperature and a decrease of the edge density. An interplay between core and edge plasma regions leads to reduced turbulence levels and outward impurity convection. These results pave the way to an attractive alternative to the standard plasmas considered for fusion energy generation in a tokamak with metallic wall environment such as the ones expected in ITER

   ↳ physics.plasm-phnucl-exPhys.Plasmas(2022)·1 citation
3. 03*

   Identification of new isomers in ${}^{228}$Ac : Impact on dark matter searches

   K. W. Kim · G. Adhikari · E. Barbosa de Souza · N. Carlin · J. J. Choi · S. Choi · M. Djamal · A. C. Ezeribe · L. E. Franca · C. Ha · I. S. Hahn · E. J. Jeon and 41 other authors

   We report the identification of metastable isomeric states of ${}^{228}$Ac at 6.28 keV, 6.67 keV and 20.19 keV, with lifetimes of an order of 100 ns. These states are produced by the $\beta$-decay of ${}^{228}$Ra, a component of the ${}^{232}$Th decay chain, with $\beta$ Q-values of 39.52 keV, 39.13 keV and 25.61 keV, respectively. Due to its low Q-value as well as the relative abundance of ${}^{232}$Th and their progeny in low background experiments, these observations potentially impact the low-energy background modeling of dark matter search experiments.

   ↳ hep-exnucl-exEPJC(2021)·0 citations
4. 04*

   Measurement methods of radial flow in relativistic heavy-ion collisions

   Peng Yang🇨🇳 · Lin Li🇨🇳 · Yu Zhou🇺🇸 · Zhiming Li🇨🇳 · Mingmei Xu🇨🇳 · Yeyin Zhao🇨🇳 · Yuanfang Wu🇨🇳

   Radial flow can be directly extracted from the azimuthal distribution of mean transverse rapidity. We apply the event-plane method and the two-particle correlation method to estimate the anisotropic Fourier coefficient of the azimuthal distribution of mean transverse rapidity. Using the event sample generated by a multiphase transport model with string melting, we show that both methods are effective. For the two-particle correlation method to be reliable, the mean number of particles in an azimuthal bin must be above a certain threshold. Using these two methods, anisotropic radial flow can be estimated in a model-independent way in relativistic heavy-ion collisions.

   ↳ nucl-thhep-phnucl-exPRC(2021)·1 citation
5. 05*

   Relativistic particle incoherent scattering by the nuclei of crystal plane atoms

   Victor V. Tikhomirov🇧🇾

   A consistent theory, which describes the incoherent scattering of classically moving relativistic particles by the nuclei of crystal planes without any phenomenological parameter is presented. The basic notions of quantum mechanics are applied to introduce a fundamental compact formula for the mean square incoherent scattering angle per unit length of particle trajectory. The latter is used to implement the effects of the crystal atom distribution inhomogeneity into the Coulomb scattering simulations without noticeable elongation of the simulation time. The theory essentially reconsiders the nature of positively charged particle dechanneling from the low nuclear density regions, being essential in both the crystal undulators and envisaged measurements of the specific electromagnetic momenta of short living particles.

   ↳ physics.acc-phhep-exnucl-exphysics.ins-det+13 citations
6. 06*

   Nucleon mass radii and distribution: Holographic QCD, Lattice QCD and GlueX data

   Kiminad A. Mamo🇺🇸 · Ismail Zahed🇺🇸

   We briefly review and expand our recent analysis for all three invariant A,B,D gravitational form factors of the nucleon in holographic QCD. They compare well to the gluonic gravitational form factors recently measured using lattice QCD simulations. The holographic A-term is fixed by the tensor $T=2^{++}$ (graviton) Regge trajectory, and the D-term by the difference between the tensor $T=2^{++}$ (graviton) and scalar $S=0^{++}$ (dilaton) Regge trajectories. The B-term is null in the absence of a tensor coupling to a Dirac fermion in bulk. A first measurement of the tensor form factor A-term is already accessible using the current GlueX data, and therefore the tensor gluonic mass radius, pressure and shear inside the proton, thanks to holography. The holographic A-term and D-term can be expressed exactly in terms of harmonic numbers. The tensor mass radius from the holographic threshold is found to be $⟨r_{GT}^2⟩\approx (0.57-0.60\mathrm{fm}{)}^2$, in agreement with $⟨r_{GT}^2⟩\approx (0.62\mathrm{fm}{)}^2$ as extracted from the overall numerical lattice data, and empirical GlueX data. The scalar mass radius is found to be slightly larger $⟨r_{GS}^2⟩\approx (0.7\mathrm{fm}{)}^2$.

   ↳ hep-phhep-latnucl-exnucl-thPRD(2021)·85 citations
7. 07*

   Neutron-neutron scattering length from the ${}^6$He$(p,p\alpha )nn$ reaction

   Matthias Göbel🇩🇪 · Thomas Aumann🇩🇪 · Carlos A. Bertulani🇺🇸 · Tobias Frederico🇧🇷 · Hans-Werner Hammer🇩🇪 · Daniel R. Phillips🇺🇸

   We propose a novel method to measure the neutron-neutron scattering length using the ${}^6$He$(p,p\alpha )nn$ reaction in inverse kinematics at high energies. The method is based on the final state interaction (FSI) between the neutrons after the sudden knockout of the $\alpha$ particle. We show that the details of the neutron-neutron relative energy distribution allow for a precise extraction of the $s$-wave scattering length. We present the state-of-the-art in regard to the theory of this distribution. The distribution is calculated in two steps. First, we calculate the ground-state wave function of ${}^6$He as a $\alpha nn$ three-body system. For this purpose we use Halo effective field theory (Halo EFT), which also provides uncertainty estimates for the results. We compare our results at this stage to model calculations done with the computer code FaCE. In a second step we determine the effects of the $nn$ FSI using the $nn$ t-matrix. We compare these FSI results to approximate FSI approaches based on standard FSI enhancement factors. While the final distribution is sensitive to the $nn$ scattering length, it depends only weakly on the effective range. Throughout we emphasize the impact of theoretical uncertainties on the neutron-neutron relative energy distribution, and discuss the extent to which those uncertainties limit the extraction of the neutron-neutron scattering length from the reaction ${}^6$He$(p,p\alpha )nn$.

   ↳ nucl-thnucl-exPRC(2021)·18 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.