Nuclear Theory·nucl-th

Tuesday·December 13, 2022

16 papers—8 primary·8 cross-listed

01
Weak decay of halo nuclei
Wael Elkamhawy🇩🇪 · Hans-Werner Hammer🇩🇪 · Lucas Platter🇺🇸
We investigate the weak decay of one-neutron halo nuclei into the proton-core continuum, i.e., beta-delayed proton emission from the halo nucleus using a cluster effective field theory for halo nuclei. On the one hand, we calculate the direct decay into the continuum. On the other hand, we consider the case of resonant final state interactions between the proton and the core. We present our formalism and discuss the application to the decay of $^{11}$ Be in detail. Moreover, we compare to recent experimental results for the branching ratio and resonance parameters. As another example, we consider the case of $^{19}$ C and predict the branching ratio for beta-delayed proton emission.
nucl-thnucl-exPRC(2023)·2 citations
02
Nuclear matter from the ladder resummation in terms of the experimental nucleon-nucleon scattering amplitudes
J. M. Alarcón🇪🇸 · J. A. Oller🇪🇸
Infinite nuclear matter is studied by resuming the series of ladder diagrams based on the results developed by us in Ann. Phys. 437, 168741 (2022). The master formula for the energy density is explicitly solved for the case of contact interactions, within a pionless description of the nucleon-nucleon interactions. Renormalized results are obtained which are directly expressed in terms of the nucleon-nucleon phase shifts and mixing angles in partial-wave amplitudes up to an including $G$ waves, with convergence reached under the inclusion of higher partial waves. The energy per particle, density and sound velocity resulting from the ladder series are given for symmetric and neutron matter. This resummation of the ladder diagrams provides a rigorous result that may be used as low-density reference for other parameterizations of $E ˉ$ for higher densities.
nucl-thcond-mat.quant-gashep-phPRC(2023)·11 citations
03
How and How Much is $g_{A}$ {\it Fundamentally} Quenched in Nuclei?
Mannque Rho🇫🇷
The superallowed Gamow-Teller transition in the doubly-magic-shell nucleus $^{100}$ Sn and the high resolution spectral shape analysis in the fourth-forbidden nonunique transition in $^{115}$ In indicate as much as $\sim 40%$ {\it fundamental} quenching in the axial-current coupling constant $g_{A}$ in nuclei. This can be attributed to an effect of the trace anomaly in QCD "emerging" in nuclear medium. If confirmed, this would signal a major revamping to do in nuclear interactions consistent with chiral-scale symmetry in nuclear medium and a big impact on $0 ν$ and $ν ν$ double $β$ decays for BSM. I present an argument that such a big anomaly-induced quenching is incompatible with how hidden scale symmetry manifests in nuclear medium, A possible means to resolve this issue is discussed in terms of hidden scale symmetry permeating in baryonic matter from normal nuclear matter to massive compact-star matter.
nucl-thhep-ph1 citation
04
Spectral function of the $η^{'}$ meson in nuclear medium based on phenomenological models
Shuntaro Sakai🇯🇵 · Daisuke Jido🇯🇵
The in-medium modification of the spectral function of the $η^{'}$ meson with and without the spatial momentum is studied with the $T ρ$ approximation by employing two phenomenological models for the $η^{'} N$ scattering; one is called coupled channels model and the other the $N (1895)$ -dominance model. In the former model, the $η^{'} N$ scattering amplitude is calculated in the unitarized coupled-channel approach involving the $η^{'} N$ channel, while in the latter model the $η^{'} N$ scattering process is dominated by the $N (1895)$ resonance with the spin and parity $J^{P} = 1/ 2^{-}$ . In the \com{coupled channels model}, one single peak of the in-medium $η^{'}$ mode appears in the spectral function and the peak position shifts to higher energies along with the increase of the nuclear density reflecting the repulsive $η^{'} N$ scattering length of the unitarized coupled-channel amplitude. On the other hand, two branches related to the $η^{'}$ and $N (1895)$ -hole modes appear in the $N (1895)$ -dominance model. In both models, the shift of the peak position and the width in the spectral function are a few tens of MeV at the normal nuclear density for the $η^{'}$ meson at rest in the nuclear medium. Once the spatial momentum is turned on, the peak positions in the spectral function approach the energies without the nuclear medium effect. Particularly, in the $N (1895)$ -dominance model, the peak strength of the $N (1895)$ -hole mode gets smaller with the finite momentum and the spectral function comes to have one single peak.
nucl-thPRC(2023)·6 citations
05
Possible neutron halo in triaxial nucleus 42Al
K. Y. Zhang · S. Q. Zhang · J. Meng
A microscopic self-consistent triaxial relativistic Hartree-Bogoliubov theory in continuum (TRHBc), which simultaneously takes into account the triaxiality and pairing correlations as well as continuum effects, is established and applied to explore the novel halo phenomenon in aluminum isotopes. The experimental proton drip line and the available data of neutron separation energies and charge radii are reproduced well without any free parameters. The neutron-richest odd-odd aluminum isotope observed so far, 42Al, is predicted to be triaxially deformed with beta=0.35 and gamma=42. Its one-neutron separation energy is predicted to be 0.68 MeV, in agreement with the AME2020, and the neutron rms radius is 3.94 fm, remarkably larger than the empirical value. The density distribution of the valance neutron, which extends much farther in space than the core, suggests a possible neutron halo in 42Al. The dominant components responsible for the spatial extension of the halo are revealed by the single-neutron orbitals around the Fermi energy. A novel phenomenon, the exchange of the intermediate and short axes between the triaxial core with beta=0.38 and gamma=50, and the triaxial halo with beta=0.79 and gamma=-23, is found. Future experiments to explore the halo phenomenon and the novel shape decoupling in 42Al are highly demanded.
nucl-thnucl-exPRC(2023)·41 citations
06
Islands of shape coexistence: theoretical predictions and experimental evidence
Andriana Martinou · Dennis Bonatsos · S.K. Peroulis · K.E. Karakatsanis · T.J. Mertzimekis · N. Minkov
Parameter-free theoretical predictions based on a dual shell mechanism within the proxy-SU(3) symmetry of atomic nuclei, as well as covariant density functional theory calculations using the DDME2 functional indicate that shape coexistence (SC) based on the particle-hole excitation mechanism cannot occur everywhere on the nuclear chart, but is restricted on islands lying within regions of 7-8, 17-20, 34-40, 59-70, 96-112, 146-168 protons or neutrons. Systematics of data for even-even nuclei possessing K=0 (beta) and K=2 (gamma) bands support the existence of these islands, on which shape coexistence appears whenever the K=0 bandhead 0_2^+ and the first excited state of the ground state band 2_1^+ lie close in energy, with nuclei characterized by 0_2^+ lying below the 2_1^+ found in the center of these islands. In addition a simple theoretical mechanism leading to multiple shape coexistence is briefly discussed.
nucl-thSymmetry(2023)·18 citations
07
Interplay of longitudinal and transverse expansion in the kinetic dynamics of heavy-ion collisions
Piotr Bozek🇵🇱
The early dynamics in heavy-ion collisions involves a rapid, far from equilibrium evolution. This early pre-equilibrium stage of the dynamics can be modeled using kinetic equations. The effect of this pre-equilibrium stage on final observables derived from transverse momenta of emitted particles is small. The kinetic equations in the relaxation time approximation for a non-boost invariant system are solved. The asymmetry of the flow with respect to the reaction plane at different rapidities is found to be very sensitive to the degree of non-equilibrium in the evolution. This suggests that the rapidity odd directed flow could be studied to identify the occurrence of non-equilibrium effects and to estimate the asymmetry of the pressure between the longitudinal and transverse directions in the collision.
nucl-thPRC(2023)·7 citations
08
Quantifying uncertainties due to optical potentials in one-neutron knockout reactions
Chloë Hebborn · T. R. Whitehead · Amy E. Lovell · Filomena M. Nunes
One-neutron knockout reactions have been widely used to extract information about the single-particle structure of nuclei from the valley of stability to the driplines. The interpretation of knockout data relies on reaction models, where the uncertainties are typically not accounted for. In this work we quantify uncertainties of optical potentials used in these reaction models and propagate them, for the first time, to knockout observables using a Bayesian analysis. We study two reactions in the present paper, the first of which involves a loosely-bound halo projectile, $^{11}$ Be, and the second a tightly-bound projectile, $^{12}$ C. We first quantify the parametric uncertainties associated with phenomenological optical potentials. Complementing to this approach, we also quantify the model uncertainties associated with the chiral forces that can be used to construct microscopic optical potentials. For the phenomenological study, we investigate the impact of the imaginary terms of the optical potential on the breakup and stripping components of the knockout cross sections as well as the impact of the angular range. For the $^{11}$ Be case, the theoretical uncertainty from the phenomenological method is on the order of the experiment uncertainty on the knockout observables; however, for the $^{12}$ C case, the theoretical uncertainty is significantly larger. The widths of the confidence intervals for the knockout observables obtained for the microscopic study and the phenomenological approach are of similar order of magnitude. Based on this work we conclude that structure information inferred from the ratio of the knockout cross sections, will carry a theoretical uncertainty of at least $20%$ for halo nuclei and at least $40%$ for tightly-bound nuclei.
nucl-thnucl-exPRC(2023)·14 citations
09
Simplified-DPN treatment of the neutron transport equation
M. Nazari · A. Zolfaghari · M. Abbasi
In this paper the simplified double-spherical harmonics SDPN, approximation of the neutron transport equation is proposed. The SDPN equations are derived from the multi-group DPN equations for N=1,2,3 (comparable to the SP3, SP5, and SP7 equations, respectively), and are converted into the form of second order multi-group diffusion equations. The finite element method with the variational approach is then used to numerically solve these equations. The computational performance of the SDPN method is compared with the SPN on several fixed-source and criticality test problems. The results show that the SDPN formulation generally results in parameters like criticality eigenvalue, disadvantage factors, absorption rate, etc. more accurately than the SPN, even up to an order of magnitude more precise, while the computational effort is the same for both methods.
↳ physics.comp-phnucl-thProg.Nucl.Energy(2023)·0 citations
10
Mesons on the light front
Meijian Li🇪🇸
This lecture note is written for 'Courses on Light-Cone Techniques applied to QCD', Nov 21-25, 2022, IGFAE. It is intended to provide basic knowledge and selective perspectives on the application of light-front Hamiltonian approach to mesons in two 1.5-hour lectures.
↳ hep-phnucl-th3 citations
11
Toward precision Fermi liquid theory in two dimensions
Silas R. Beane · Gianluca Bertaina · Roland C. Farrell · William R. Marshall
The ultra-cold and weakly-coupled Fermi gas in two spatial dimensions is studied in an effective field theory framework. It has long been observed that universal corrections to the energy density to two orders in the interaction strength do not agree with Monte Carlo simulations in the weak-coupling regime. Here, universal corrections to three orders in the interaction strength are obtained for the first time, and are shown to provide agreement between theory and simulation. Special consideration is given to the scale ambiguity associated with the non-trivial renormalization of the singular contact interactions. The isotropic superfluid gap is obtained to next-to-leading order, and nonuniversal contributions to the energy density due to effective range effects, p-wave interactions and three-body forces are computed. Results are compared with precise Monte Carlo simulations of the energy density and the contact in the weakly-coupled attractive and repulsive Fermi liquid regimes. In addition, the known all-orders sum of ladder and ring diagrams is compared with Monte Carlo simulations at weak coupling and beyond.
↳ cond-mat.quant-gasnucl-thPRA(2023)·3 citations
12
Dynamical solution of the strong CP problem within QCD ?
Gerrit Schierholz🇩🇪
The strong CP problem is inseparably connected with the topology of gauge fields and the mechanism of color confinement, which requires nonperturbative tools to solve it. In this talk I present results of a recent lattice investigation of QCD with the $θ$ term in collaboration with Yoshifumi Nakamura. The tool we are using to address the nonperturbative properties of the theory is the gradient flow, which is a particular realization of momentum space RG transformations. The novel result is that within QCD the vacuum angle $θ$ is renormalized, together with the strong coupling constant, and flows to $θ = 0$ in the infrared limit. This means that CP is conserved by the strong interactions.
↳ hep-lathep-phhep-thnucl-thEPJ Web Conf.(2022)·8 citations
13
Deep Inelastic Scattering with Application to Nuclear Targets: Lectures at the 1985 Los Alamos School on Relativistic Dynamics and Quark Nuclear Physics
Robert L. Jaffe🇺🇸
This paper is essentially a verbatim reconstruction of lectures that I gave at the Los Alamos School on Relativistic Dynamics and Quark Nuclear Physics in 1985. They were published in the school proceedings, but the book is not widely available. The Los Alamos School took place at the height of the first wave of interest in the quark substructure of nuclei, stimulated by the 1983 discovery of the EMC Effect. Interest in this subject has been increasing for years and the prospect of a dedicated Electron Ion Collider within the decade guarantees even greater attention to quarks and gluons in nuclei among both theorists and experimentalists. Recently, to my surprise, I learned that copies of my old lectures have been circulating and been found useful by the relatively few people who know about them. The are, of course, dated: experiments have far outstripped what was available 37 years ago and theory has progressed too. However, the rest frame derivation of the parton model, the derivation and discussion of the convolution formalism for nucleons, nucleon correlations, and other, virtual, constituents of nuclei, and sections on scaling violation and the operator product expansion have aged pretty well and seem to still be useful. With the help and encouragement of Richard Milner, I have recreated the LaTeX files necessary to post the 1985 Lectures on the arXiv, making them available to the nuclear and particle physics community. Apart from correcting some typographical errors, I have made no attempt to edit, improve, or update these lectures. I hope readers will nevertheless find them useful.
↳ hep-phhep-thnucl-exnucl-thPublished in M. B. Johnson and A. Pickles…·9 citations
14
A scheme for excitation of thorium-229 nuclei based on the electronic bridge excitaion
Lin Li · Zi Li · Chen Wang · Wen-Ting Gan · Xia Hua · Xin Tong
Thorium-229 possesses the lowest nuclear first excited state with an energy of about 8 eV. The extremely narrow linewidth of the nuclear first excited state with the uncertainty of 53 THz prevents the direct laser excitation and the realization of the nuclear clock. We present a proposal using the Coulomb crystal of a linear chain formed by the $^{229}$ Th $^{3 +}$ ions, the nuclei of $^{229}$ Th $^{3 +}$ ions in the ion trap are excited by the electronic bridge (EB) process. The 7 $P_{1/2}$ state of the thorium-229 nuclear ground state is chosen for the EB excitation. Using the two-level optical Bloch equation under experimental conditions, we calculate that 2 out of 36 prepared thorium ions in the Coulomb crystal can be excited to the nuclear first excited state, and it takes about 2 hours to scan over the uncertainty of 0.22 eV. Taking the advantage of transition enhancement of the EB and the long stability of the Coulomb crystal, the energy uncertainty of the first excited state can be limited to the order of 1 GHz.
↳ physics.atom-phnucl-thNucl.Sci.Tech.(2023)·10 citations
15
Finite size effect on the thermodynamics of a hot and magnetized hadron resonance gas
Debasis Atta🇮🇳 · Nilanjan Chaudhuri🇮🇳 · Snigdha Ghosh🇮🇳
The thermodynamic properties of a non-interacting ideal Hadron Resonance Gas (HRG) of finite volume have been studied in the presence of an external magnetic field. The inclusion of background magnetic field in the calculation of thermodynamic potential is done by the modification of the dispersion relations of the charged hadrons in terms of Landau quantization. The generalized Matsubara prescription has been employed to take into account the finite size effects in which a periodic (anti-periodic) boundary conditions is considered for the mesons (baryons). We find significant effects of the magnetic field as well as system size on the temperature dependence of energy density, longitudinal and transverse pressure especially in low temperature regions. The HRG is found to exhibit diamagnetism (paramagnetism) in the low (high) temperature region whereas the finite size effect is seen to strengthen the diamagnetic behavior of the medium.
↳ hep-phnucl-thMod.Phys.Lett.A(2022)·3 citations
16
Comparing the MARTINI and CUJET models for jet-quenching: Medium modification of jets and jet substructure
Shuzhe Shi🇺🇸 · Rouzbeh Modarresi Yazdi🇨🇦 · Charles Gale🇨🇦 · Sangyong Jeon🇨🇦
Jets produced by the initial hard scattering in heavy ion collision events lose energy due to interactions with the color-deconfined medium formed around them: the quark-gluon plasma (QGP). Jet-medium interactions constitute an important theoretical and experimental field for studies of QGP, and various models with different assumptions have been proposed to describe them. A fair and direct comparison of these models requires that all other aspects of the simulation be fixed, which is achieved in this work by relying on the JETSCAPE framework. We employ JETSCAPE to directly and comprehensively compare two successful energy loss models: CUJET and MARTINI. We compare the models with the results of measurements of jet spectra and substructure observables. With the strong coupling tuned separately, we find that the two models broadly agree with each other in nuclear modification factors for charged hadrons and jets with cone size $R = 0.4$ . Systematic differences are reported in fragmentation functions, jet shape, and cone size dependent jet $R_{AA}$ .
↳ hep-phnucl-thPRC(2023)·16 citations

Affiliations

first authorsco-authorsvia INSPIRE