Nuclear Theory·nucl-th

Thursday·July 8, 2021

10 papers—5 primary·5 cross-listed

01
[Submitted on 7 Jul 2021]
Phase-dependent cross sections of deuteron-triton fusion in dichromatic intense fields with high-frequency limit
Wenjuan Lv · Hao Duan · Jie Liu
We investigate the influence of strong dichromatic laser fields (i.e. 1{\omega}-2{\omega} and 1{\omega}-3{\omega}) with high-frequency limit on the cross sections of deuteron-triton(DT) fusion in Kramers-Henneberger(KH) frame. We focus on the transitions of phase-dependent effects depending on a dimensionless quantity n_{d} , which equals the ratio of the quiver oscillation amplitude to the geometrical touching radius of the deuteron and triton as defined in our previous research. Theoretical calculations show that the angle-dependent as well as phase-dependent Coulomb barrier penetrabilities can be enhanced in dichromatic intense fields, and the corresponding angle-averaged penetrabilities and the fusion cross sections increase significantly compared with field-free case. Moreover, we find that there are twice shifts of the peak in the cross sections whenever the frequency becomes sufficiently low or the intensity sufficiently high. The reason for the first shift is the angle-dependence effects for sub-barrier fusion, while the second shift is due to the accumulation of over-barrier fusion, these mechanisms are analyzed in detail in this paper.
Comments:
6 pages, 5 figures
Subjects:
Nuclear Theory (nucl-th)
arXiv:
2107.03085 [pdf]
EPJA(2022)·14 citations
02
[Submitted on 7 Jul 2021]
Generalized seniority isomers in and around $Z = 82$ closed shell: a survey of Hg, Pb and Po isotopes
Bhoomika Maheshwari · Deepika Choudhury · Ashok Kumar Jain
In this paper, we investigate the generalized seniority scheme and the validity of Generalized Seniority Schmidt Model in and around the $Z = 82$ semi-magic region. A consistently same multi-j configuration is used to explain all the nuclear spectroscopic properties such as $g -$ factors, $Q -$ moments and $B (E 2)$ trends for the $13/2^{+}$ , $12^{+}$ and $33/2^{+}$ isomers in all the three Hg, Pb and Po isotopic chains. The inverted parabolic $B (E 2)$ trends for the first $2^{+}$ states in Hg, Pb and Po isotopes are also explained using the generalized seniority scheme. A comparison with the experimental data is presented, wherever possible, and future possibilities are suggested.
Comments:
Accepted in Nuclear Physics A
Subjects:
Nuclear Theory (nucl-th)
arXiv:
2107.03156 [pdf]
NPA(2021)·9 citations
03
[Submitted on 7 Jul 2021]
Perturbative correction to the adiabatic approximation for $(d, p)$ reactions
Laura Moschini · Natalia K. Timofeyuk · Ronald C. Johnson
The adiabatic distorted wave approximation (ADWA) is widely used by the nuclear community to analyse deuteron stripping ( $d$ , $p$ ) experiments. It provides a quick way to take into account an important property of the reaction mechanism: deuteron breakup. In this work we provide a numerical quantification of a perturbative correction to this theory, recently proposed in [R.C. Johnson, J. Phys. G: Nucl. Part. Phys. 41 (2014) 094005] for separable rank-one nucleon-proton potentials. The correction involves an additional, nonlocal, term in the effective deuteron-target ADWA potential in the entrance channel. We test the calculations with perturbative corrections against continuum-discretized coupled channel predictions which treat deuteron breakup exactly.
Subjects:
Nuclear Theory (nucl-th)
arXiv:
2107.03233 [pdf]
J.Phys.G(2021)·1 citation
04
[Submitted on 7 Jul 2021]
Tracing the dynamical interplay of low-energy reaction processes of exotic nuclei using a two-center molecular continuum
Laura Moschini · Alexis Diaz-Torres
The competition among reaction processes of a weakly-bound projectile at intermediate times of a slow collision has been unraveled. This has been done using a two-center molecular continuum within a semiclassical, time-dependent coupled-channel reaction model. Dynamical probabilities of elastic scattering, transfer and breakup agree with those derived from the direct integration of the time-dependent Schrödinger equation, demonstrating the usefulness of a two-center molecular continuum for gaining insights into the reaction dynamics of exotic nuclei.
Subjects:
Nuclear Theory (nucl-th)
arXiv:
2107.03260 [pdf]
PLB(2021)·5 citations
05
[Submitted on 7 Jul 2021]
Machine-learning approach to finite-size effects in systems with strongly interacting fermions
Nawar Ismail · Alexandros Gezerlis
We investigate the applicability of machine learning techniques in studying the finite-size effects associated with many-body physics. These techniques have an emerging presence in many-body theory as they have been used for interpolations, extrapolations, and in modeling wavefunctions. We will resolve several issues associated with machine learning and many-body calculations such as small datasets, outliers, and discontinuities, for the purpose of extrapolating finite calculations to macroscopic scales. We carry out a systematic investigation of two related systems by developing metrics that aim to avoid spurious effects and capture desired features. This work uses neural networks to extrapolate the Unitary Gas to the thermodynamic limit at zero-range, which is otherwise difficult to reach. The effective mass of strongly interacting neutron matter is also studied and makes use of the non-interacting problem to resolve discontinuous predictions. For this investigation, we also carried out new Auxiliary Field Diffusion Monte Carlo (AFDMC) calculations for a variety of densities and particle numbers. Ultimately, we demonstrate an effective utility for neural networks in this context.
Comments:
10 pages, 9 figures; v2 corresponds to published version
Subjects:
Nuclear Theory (nucl-th); Quantum Gases (cond-mat.quant-gas); Computational Physics (physics.comp-ph)
arXiv:
2107.03330 [pdf]
PRC(2021)·9 citations
06
[Submitted on 6 Jul 2021] (cross-list from hep-lat)
Thermal monopole condensation in QCD with physical quark masses
Marco Cardinali🇮🇹 · Massimo D'Elia🇮🇹 · Andrea Pasqui🇮🇹
Thermal monopoles, identified after Abelian projection as magnetic currents wrapping non-trivially around the thermal circle, are studied in $N_{f} = 2 + 1$ QCD at the physical point. The distribution in the number of wrappings, which in pure gauge theories points to a condensation temperature coinciding with deconfinement, points in this case to around 275 MeV, almost twice the QCD crossover temperature $T_{c}$ ; similar indications emerge looking for the formation of a percolating current cluster. The possible relation with other non-perturbative phenomena observed above $T_{c}$ is discussed.
Comments:
6 pages, 4 figures. Fig. 4 has been updated. References added
Subjects:
High Energy Physics — Lattice (hep-lat); High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Theory (hep-th); Nuclear Theory (nucl-th)
arXiv:
2107.02745 [pdf]
17 citations
07
[Submitted on 6 Jul 2021] (cross-list from hep-ph)
Interpretation of neutral charm mesons near threshold as unparticles
Eric Braaten🇺🇸 · Hans-Werner Hammer🇩🇪
The existence of the $X (3872)$ resonance extremely close to the $D^{* 0} D ˉ^{0}$ threshold implies that neutral charm mesons have an approximate nonrelativistic conformal symmetry. Systems consisting of these mesons with small kinetic energies produced in a short-distance reaction are unparticles in the sense that they can be created by operators with definite scaling dimensions in a nonrelativistic conformal field theory. There is a scaling region in which their energy distribution has power-law behavior with an exponent determined by the scaling dimension of the operator. The unparticle associated with two neutral charm mesons produces a peak in the recoil momentum spectrum of $K^{\pm}$ in inclusive decays of $B^{\pm}$ that has been observed. The scaling dimensions of the unparticles associated with three neutral charm mesons are calculated. They can be determined experimentally by measuring the invariant mass distributions for $X D^{0}$ or $X D^{* 0}$ in inclusive prompt production at the Large Hadron Collider.
Comments:
5 pages, 4 figures, title changed, final version
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
2107.02831 [pdf]
PRL(2022)·14 citations
08
[Submitted on 6 Jul 2021] (cross-list from hep-ph)
Spin contribution to the dissociation of bound states in rotating medium in magnetic field
Kirill Tuchin🇺🇸
Magneto-rotational dissociation is the decay, by the way of tunneling, of a rotating bound state in the magnetic field. The corresponding probability was recently computed in the quasi-classical approximation using the Imaginary Time Method and was shown to increase with the angular velocity and decrease with the magnetic field strength \cite{Tuchin:2021lxl}. This letter reports the calculation of the quantum correction to the dissociation probability associated with the spin of the tunneling particle. The quasi-classical motion of spin is described by the Bargmann--Michel--Telegdi equation in the rotating frame. It is shown that the spin contribution significantly increases the dissociation probability. Applications to the Quark-Gluon Plasma are touched upon.
Comments:
11 pages, 12 figures, v3: typos corrected, comments added. arXiv admin note: text overlap with arXiv:2102.10659
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
2107.02863 [pdf]
NPA(2021)·5 citations
09
[Submitted on 7 Jul 2021] (cross-list from hep-ph)
Remarks on non-perturbative three--body dynamics and its application to the $K K K ˉ$ system
Xu Zhang🇩🇪 · Christoph Hanhart🇩🇪 · Ulf-G. Meißner🇩🇪 · Ju-Jun Xie🇨🇳
A formalism is discussed that allows for a straightforward treatment of the relativistic three-body problem while keeping the correct analytic structure. In particular it is demonstrated that sacrificing covariance for analyticity can be justified by the hierarchy of different contributions in the spirit of an effective field theory. For definiteness the formalism is applied to the $K K K ˉ$ system allowing for the emergence of the $a_{0} (980)$ and the $f_{0} (980)$ as hadronic molecules. For simplicity all inelastic channels are switched off.
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Experiment (hep-ex); Nuclear Theory (nucl-th)
arXiv:
2107.03168 [pdf]
EPJA(2022)·22 citations
10
[Submitted on 7 Jul 2021] (cross-list from nucl-ex)
Using spin alignment of inelastically-excited fast beams to make spin assignments: the spectroscopy of 13O as a test case
R.J. Charity🇺🇸 · T.B. Webb🇺🇸 · J.M. Elson🇺🇸 · D.E.M. Hoff🇺🇸 · C.D. Pruitt🇺🇸 · L.G. Sobotka🇺🇸 · P. Navratil🇨🇦 · G. Hupin🇫🇷 · K. Kravvaris🇺🇸 · S. Quaglioni🇺🇸 · K.W. Brown🇺🇸 · G. Cerizza🇺🇸 and 14 other authors
Excited states in 13O were investigated using inelastic scattering of an E/A=69.5-MeV 13O beam off of a 9Be target. The excited states were identified in the invariant-mass spectra of the decay products. Both single proton and sequential two-proton decays of the excited states were examined. For a number of the excited states, the protons were emitted with strong anisotropy where emissions transverse to the beam axis are favored. The measured proton-decay angular distributions were compared to predictions from distorted-wave born-approximation (DWBA) calculations of the spin alignment which was shown to be largely independent of the excitation mechanism. The deduced $^{13}$ O level scheme is compared to ab initio no-core shell model with continuum (NCSMC) predictions. The lowest-energy excited states decay isotropically consistent with predictions of strong proton 1s1/2 structure. Above these states in the level scheme, we observed a number of higher-spin states not predicted within the model. Possibly these are associated with rotational bands built on deformed cluster configurations predicted by antisymmetrized molecular dynamics (AMD) calculations. The spin alignment mechanism is shown to be useful for making spin assignments and may have widespread use.
Subjects:
Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
arXiv:
2107.03346 [pdf]
PRC(2021)·7 citations

Affiliations

first authorsco-authorsvia INSPIRE