Nuclear Theory·nucl-th

Monday·March 4, 2019

9 papers—7 primary·2 cross-listed

01
Renormalization of a Finite Range Inverse Cube Potential
Daniel Odell · Arnoldas Deltuva · Jose Bonilla · Lucas Platter
We study the regularization and renormalization of a finite range inverse cube potential in the two- and three-body sectors. Specifically, we compare and contrast three different regulation schemes frequently used to study few-body systems as well as the associated renormalization group flows. We also calculate bound state and scattering observables over a wide range of cutoffs, demonstrating the sufficiency of a two-body contact interaction to renormalize two- and three-body observables. We supplement these plots with quantified analyses of the observables' residual cutoff dependence.
nucl-thPRC(2019)·8 citations
02
Structures and decay properties of extremely proton-rich nuclei $^{11, 12}$ O
S. M. Wang · W. Nazarewicz · R. J. Charity · L. G. Sobotka
$Background :$ The recent observation of the unbound nucleus $^{11}$ O offers the unique possibility to study how the structure and dynamics of two-proton ( $2 p$ ) decay is affected by the removal of one neutron from $^{12}$ O, and provides important information on the Thomas-Ehrman effect in the mirror pairs $_{8}^{11}$ O $_{3}$ - $_{3}^{11}$ Li $_{8}$ and $_{8}^{12}$ O $_{4}$ - $_{4}^{12}$ Be $_{8}$ , which involve the $2 p$ emitters $^{11}$ O and $^{12}$ O. $Purpose :$ We investigate how continuum effects impact the structure and decay properties of $^{11}$ O and $^{12}$ O, and their mirror partners. $Methods :$ We solve the three-body core-nucleon-nucleon problem using the Gamow coupled-channel (GCC) method. The GCC Hamiltonian employs a realistic finite-range valence nucleon-nucleon interaction and the deformed cores of $^{9, 10}$ C, $^{9}$ Li, and $^{10}$ Be. $Results :$ We calculate the energy spectra and decay widths of $^{11}$ O and $^{12}$ O as well as those of their mirror nuclei. In particular, we investigate the dynamics of the $2 p$ decay in the ground state of $^{12}$ O by analyzing the evolution of the $2 p$ configuration of the emitted protons as well as their angular correlations in the coordinate space. We also show how the analytic structure of the resonant states of $^{10}$ Li and $^{10}$ N impacts the low-lying states of $^{11}$ Li and $^{11}$ O. $Conclusions :$ We demonstrate that, in both nuclei $^{11}$ O and $^{12}$ O, there is a competition between direct and "democratic" $2 p$ ground-state emission. The broad structure observed in $^{11}$ O is consistent with four broad resonances, with the predicted $3/ 2_{1}^{-}$ ground state strongly influenced by the broad threshold resonant state in $^{10}$ N, which is an isobaric analog of the antibound (or virtual) state in $^{10}$ Li.
nucl-thPRC(2019)·40 citations
03
Discrepancy between experimental and theoretical $β$ -decay rates resolved from first principles
P. Gysbers🇨🇦 · G. Hagen🇺🇸 · J. D. Holt🇨🇦 · G. R. Jansen🇺🇸 · T. D. Morris🇺🇸 · P. Navratil🇨🇦 · T. Papenbrock🇺🇸 · S. Quaglioni🇺🇸 · A. Schwenk🇩🇪 · S. R. Stroberg🇨🇦 · K. A. Wendt🇺🇸
$β$ -decay, a process that changes a neutron into a proton (and vice versa), is the dominant decay mode of atomic nuclei. This decay offers a unique window to physics beyond the standard model, and is at the heart of microphysical processes in stellar explosions and the synthesis of the elements in the Universe. For 50 years, a central puzzle has been that observed $β$ -decay rates are systematically smaller than theoretical predictions. This was attributed to an apparent quenching of the fundamental coupling constant $g_{A} ≃$ 1.27 in the nucleus by a factor of about 0.75 compared to the $β$ -decay of a free neutron. The origin of this quenching is controversial and has so far eluded a first-principles theoretical understanding. Here we address this puzzle and show that this quenching arises to a large extent from the coupling of the weak force to two nucleons as well as from strong correlations in the nucleus. We present state-of-the-art computations of $β$ -decays from light to heavy nuclei. Our results are consistent with experimental data, including the pioneering measurement for $^{100}$ Sn. These theoretical advances are enabled by systematic effective field theories of the strong and weak interactions combined with powerful quantum many-body techniques. This work paves the way for systematic theoretical predictions for fundamental physics problems. These include the synthesis of heavy elements in neutron star mergers and the search for neutrino-less double- $β$ -decay, where an analogous quenching puzzle is a major source of uncertainty in extracting the neutrino mass scale.
nucl-thNat.Phys.(2019)·381 citations
04
The $S_{E 1}$ factor of radiative $α$ capture on $^{12}$ C in effective field theory
Shung-Ichi Ando (Sunmoon U.)
The $S_{E 1}$ factor of radiative $α$ capture on $^{12}$ C is studied in effective field theory. We briefly discuss the strategy for the calculation of the reaction and report a first result of $S_{E 1}$ at the Gamow-peak energy, $E_{G} = 0.3$ ~MeV.
nucl-thSpringer Proc.Phys.(2020)·1 citation
05
Masses of ground-state mesons and baryons, including those with heavy quarks
Pei-Lin Yin🇨🇳 · Chen Chen🇧🇷 · Gastao Krein🇧🇷 · Craig D. Roberts🇺🇸 · Jorge Segovia🇪🇸 · Shu-Sheng Xu🇨🇳
Using a confining, symmetry-preserving regularisation of a vector $\times$ vector contact interaction, we compute the spectra of ground-state pseudoscalar and vector $(f g ˉ)$ mesons, scalar and axial-vector $(f g)$ diquarks, and $J^{P} = 1/ 2^{+}, 3/ 2^{+}$ $(f g h)$ baryons, where $f, g, h \in {u, d, s, c, b}$ . The diquark correlations are essentially dynamical and play a key role in formulating and solving the three-valence-quark baryon problems. The baryon spectrum obtained from this largely-algebraic approach reproduces the 22 known experimental masses with an accuracy of $2.9 (2.4)$ %. It also possesses the richness of states typical of constituent-quark models, predicting many heavy-quark baryons not yet observed. This study indicates that diquark correlations are an important component of all baryons; and owing to the dynamical character of the diquarks, it is typically the lightest allowed diquark correlation which defines the most important component of a baryon's Faddeev amplitude.
nucl-thhep-lathep-phPRD(2019)·112 citations
06
Importance of initial and final state effects for azimuthal correlations in p+Pb collisions
Moritz Greif🇩🇪 · Carsten Greiner🇩🇪 · Björn Schenke🇺🇸 · Sören Schlichting🇺🇸 · Zhe Xu🇨🇳
We study the influence and interplay of initial state and final state effects in the dynamics of small systems, focusing on azimuthal correlations at different multiplicities. To this end we introduce a new model, matching the classical Yang-Mills dynamics of pre-equilibrium gluon fields (IP-GLASMA) to a perturbative QCD based parton cascade for the final state evolution (BAMPS) on an event-by-event basis. Depending on multiplicity of the event, we see transverse momentum dependent signatures of the initial, but also the final state in azimuthal correlation observables, such as $v_{2} {2 P C} (p_{T})$ . In low-multiplicity events, initial state correlations dominate for transverse momenta $p_{T} > 2 GeV$ , whereas in high-multiplicity events and at low momenta final state interactions dominate and initial state correlations strongly affect $v_{2} {2 P C} (p_{T})$ for $p_{T} > 2 GeV$ as well as the $p_{T}$ integrated $v_{2} {2 P C}$ . Nearly half of the final pT integrated $v_{2} {2 P C}$ is contributed by the initial state in low-multiplicity events, whereas in high-multiplicity the share is much less. Based on Ref. [1], we are now able to carry out a systematic multiplicity scan, probing the dynamics on the border of initial state dominated to final state dominated - but not yet hydrodynamic regime.
nucl-thhep-phNPA(2019)·2 citations
07
Revisiting fission-probability data using $R$ -matrix Monte-Carlo simulations : application to Pu fissile isotopes over the 4 to 8 MeV excitation energy range
O. Bouland🇫🇷 · B. Jurado🇫🇷
This article describes an original approach to analyze simultaneously cross sections and surrogate data measurements using efficient Monte Carlo extended $R$ -matrix theory algorithm based on unique set of nuclear structure parameters. The alternative analytical path based on the manifold Hauser-Feshbach equation was intensively used in this work to gauge the errors carried by the surrogate-reaction method commonly taken to predict neutron-induced cross sections from observed partial decay probabilities. Present paper emphasizes in particular a dedicated way to treat direct reaction entrance and prior decay excited nucleus outgoing channels widths correlations. Present smart theoretical foundation brought the opportunity to apply successfully our method to both fission-probability data and directly measured neutron cross sections according to Pu fissile isotopes; namely the $^{237, 238, 240, 242 an d 244}$ Pu $^{*}$ nuclei. This new capability opens genuine perspectives in matter of 'evaluation process' from foreseen fission- and $γ$ -decay probabilities simultaneously measured as derived data will become available.
nucl-thphysics.app-phPRC(2019)·8 citations
08
Neutrino Quantum Kinetics in Compact Objects
Sherwood A. Richers🇺🇸 · Gail C. McLaughlin🇺🇸 · James P. Kneller🇺🇸 · Alexey Vlasenko🇺🇸
Neutrinos play a critical role of transporting energy and changing the lepton density within core-collapse supernovae and neutron star mergers. The quantum kinetic equations (QKEs) combine the effects of neutrino-matter interactions treated in classical Boltzmann transport with the neutrino flavor-changing effects treated in neutrino oscillation calculations. We present a method for extending existing neutrino interaction rates to full QKE source terms for use in numerical calculations. We demonstrate the effects of absorption and emission by nucleons and nuclei, electron scattering, electron-positron pair annihilation, nucleon-nucleon bremsstrahlung, neutrino-neutrino scattering. For the first time, we include all these collision terms self-consistently in a simulation of the full isotropic QKEs in conditions relevant to core-collapse supernovae and neutron star mergers. For our choice of parameters, the long-term evolution of the neutrino distribution function proceeds similarly with and without the oscillation term, though with measurable differences. We demonstrate that electron scattering, nucleon-nucleon bremsstrahlung processes, and four-neutrino processes dominate flavor decoherence in the protoneutron star (PNS), absorption dominates near the shock, and all of the considered processes except elastic nucleon scattering are relevant in the decoupling region. Finally, we propose an effective decoherence opacity that at most energies predicts decoherence rates to within a factor of 10 in our model PNS and within 20% outside of the PNS.
↳ astro-ph.HEhep-phnucl-thPRD(2019)·95 citations
09
The energy-momentum tensor of spin-1 hadrons: formalism
Wim Cosyn🇧🇪 · Sabrina Cotogno🇫🇷 · Adam Freese🇺🇸 · Cédric Lorcé🇫🇷
We provide the complete decomposition of the local gauge-invariant energy-momentum tensor for spin-1 hadrons, including non-conserved terms for the individual parton flavors and antisymmetric contributions originating from intrinsic spin. We state sum rules for the gravitational form factors appearing in this decomposition and provide relations for the mass decomposition, work balance, total and orbital angular momentum, mass radius, and inertia tensor. Generalizing earlier work, we derive relations between the total and orbital angular momentum and the Mellin moments of twist-2 and 3 generalized parton distributions, accessible in hard exclusive processes with spin-1 targets. Throughout the work, we comment on the unique features in these relations originating from the spin-1 nature of the hadron, being absent in the lower spin cases.
↳ hep-phnucl-exnucl-thEPJC(2019)·66 citations

Affiliations

first authorsco-authorsvia INSPIRE