Nuclear Theory·nucl-th

Tuesday·August 18, 2020

14 papers—8 primary·6 cross-listed

01
[Submitted on 14 Aug 2020]
Discovery vs. Precision in Nuclear Physics- A Tale of Three Scales
Gerald A. Miller🇺🇸
At least three length scales are important in gaining a complete understanding of the physics of nuclei. These are the radius of the nucleus, the average inter-nucleon separation distance, and the size of the nucleon. The connections between the different scales are examined by using examples that demonstrate the direct connection between short-distance and high momentum transfer physics and also that significant high momentum content of wave functions is inevitable. The nuclear size is connected via the independent-pair approximation to the nucleon-nucleon separation distance, and this distance is connected via the concept of virtuality to the EMC effect. An explanation of the latter is presented in terms of light-front holographic wave functions of QCD. The net result is that the three scales are closely related, so that a narrow focus on any given specific range of scales may prevent an understanding of the fundamental origins of nuclear properties. It is also determined that, under certain suitable conditions, experiments are able to measure the momentum dependence of wave functions.
Comments:
22 pages, 10 figures
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph); Nuclear Experiment (nucl-ex)
arXiv:
2008.06524 [pdf]
PRC(2020)·9 citations
02
[Submitted on 14 Aug 2020]
Ab initio neutrinoless double-beta decay matrix elements for 48Ca, 76Ge, and 82Se
A. Belley🇨🇦 · C. G. Payne🇨🇦 · S. R. Stroberg🇺🇸 · T. Miyagi🇨🇦 · J. D. Holt🇨🇦
We calculate basis-space converged neutrinoless $β β$ decay nuclear matrix elements for the lightest candidates: 48Ca, 76Ge and 82Se. Starting from initial two- and three-nucleon forces, we apply the ab initio in-medium similarity renormalization group to construct valence-space Hamiltonians and consistently transformed $β β$ -decay operators. We find that the tensor component is non-negligible in 76Ge and 82Se, and resulting nuclear matrix elements are overall 25-45% smaller than those obtained from the phenomenological shell model. While a final matrix element with uncertainties still requires substantial developments, this work nevertheless opens a path toward a true first-principles calculation of neutrinoless $β β$ decay in all nuclei relevant for ongoing large-scale searches.
Comments:
6 pages, 3 figures, final published version
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph); Nuclear Experiment (nucl-ex)
arXiv:
2008.06588 [pdf]
PRL(2021)·134 citations
03
[Submitted on 15 Aug 2020]
Improvements to the macroscopic-microscopic approach of nuclear fission
Marc Verriere · Matthew R. Mumpower
The well established macroscopic-microscopic (mac-mic) description of nuclear fission enables the prediction of fission fragment yields for a broad range of fissioning systems. In this work, we present several key enhancements to this approach. We improve upon the microscopic sector of nuclear potential energy surfaces by magnifying the resolution of the Lipkin-Nogami equations and strengthening the Strutinsky procedure, thus reducing spurious effects from the continuum. We further present a novel deterministic method for calculating fission dynamics under the assumption of strongly damped nucleonic motion. Our technique directly determines the evolution of the scissioned shape distribution according to the number of random walk steps rather than the statistical accumulation of fission events. We show that our new technique is equivalent to the Metropolis random walk pioneered over the past decade by Randrup and colleagues. It further improves upon it, as we remove the need for altering the nuclear landscape via a biased potential. With our final improvement, we calculate fission fragments mass and charge distributions using particle number projection, which affords the simultaneous calculation of both mass and charge yield distributions. Fission fragments are thus calculated from the quantum mechanical $A$ -body states of the potential energy surface rather than the collective mass asymmetry variable ( $α_{g}$ ) of the Finite-Range Liquid-Drop Model (FRLDM) used in past work. We highlight the success of our enhancements by predicting the odd-even staggering and the charge polarization for the neutron-induced fission of $^{233}$ U and $^{235}$ U.
Subjects:
Nuclear Theory (nucl-th)
arXiv:
2008.06639 [pdf]
PRC(2021)·21 citations
04
[Submitted on 15 Aug 2020]
Role of $Δ$ s in determining the properties of Neutron Stars in parameterized hydrostatic equilibrium
Debashree Sen🇮🇳
The possible existence of $Δ$ resonances is inspected in the cold dense matter of neutron star (NS) core in presence of the hyperons. The diverse effects of variation in $Δ$ mass on their formation and the equation of state (EoS) are studied in this work with an effective chiral model and the resultant NS properties are calculated with the help of parameterized Tolman-Oppenheimer-Volkoff equations (PTOV) to bring out the two important features of pressure in the context of massive NSs. The $Δ$ puzzle is re-explored and resolved taking into account the concept of modified/parameterized inertial pressure and self-gravity in case of massive pulsars like PSR J1614-2230 and PSR J0348-0432. It is seen that although the presence of exotic matter like the hyperons and the $Δ$ s softens the EoS considerably, their presence in massive NSs can be successfully explained with the theory of parameterized hydrostatic equilibrium conditions. The results of this work also satisfy the constraints on $R_{1.4}$ and $R_{1.6}$ from the gravitational wave (GW170817) detection of binary NS merger. The constraint on baryonic mass from PSR J0737-3039 is also satisfied with the solutions of the PTOV equations for all the $Δ$ masses considered.
Comments:
24 pages, 9 figures
Subjects:
Nuclear Theory (nucl-th)
arXiv:
2008.06753 [pdf]
Int.J.Mod.Phys.D(2019)·7 citations
05
[Submitted on 15 Aug 2020]
Binding of antikaons and Lambda(1405) clusters in light kaonic nuclei
Yoshiko Kanada-En'yo🇯🇵
The energy spectra of light-mass kaonic nuclei were investigated using the theoretical framework of the $0 s$ -orbital model with zero-range $K ˉ N$ and $K ˉ K ˉ$ interactions of effective single-channel real potentials. The energies of the $K ˉ N N$ , $K ˉ N N N$ , $K ˉ N N N N$ , $K ˉ K ˉ N$ , and $K ˉ K ˉ N N$ systems were calculated in the cases of weak- and deep-binding of the $K ˉ N$ interaction, which was adjusted to fit the $Λ (1405)$ mass with the energy of the $K ˉ N$ bound state. The results qualitatively reproduced the energy systematics of kaonic nuclei calculated via other theoretical approaches. In the energy spectra of the $K ˉ N N$ and $K ˉ K ˉ N N$ systems, the lowest states $K ˉ N N (J^{π}, T = 0^{-}, 1/2)$ and $K ˉ K ˉ N N (0^{+}, 0)$ were found to have binding energies approximately twice and four times as large as that of the $K ˉ N (1/ 2^{-}, 0)$ state, respectively. Higher $(J^{π}, T)$ states including $K ˉ N N (1^{-}, 1/2)$ , $K ˉ K ˉ N N (0^{+}, 1)$ , and $K ˉ K ˉ N N (1^{+}, 1)$ were predicted at energies of 9--25 MeV below the antikaon-decay threshold. The effective $Λ (1405)$ - $Λ (1405)$ interaction in the $K ˉ K ˉ N N$ system was also investigated via a $K ˉ N + K ˉ N$ -cluster model. Strong and weak $Λ (1405)$ - $Λ (1405)$ attractions were obtained in the $S^{π} = 0^{+}$ and $S^{π} = 1^{-}$ channels, respectively. The $Λ (1405)$ - $Λ (1405)$ interaction in the $ $K ˉ K ˉ N N$ system was compared with the effective $d$ - $d$ interaction in the $N N N N$ system, and the properties of dimer-dimer interactions in hadron and nuclear systems were discussed.
Comments:
16 pages, 4 figures
Subjects:
Nuclear Theory (nucl-th)
arXiv:
2008.06802 [pdf]
EPJA(2021)·6 citations
06
[Submitted on 16 Aug 2020]
A bag model of matter condensed by the strong interaction
Zhi-Qiang Miao🇨🇳 · Cheng-Jun Xia🇨🇳 · Xiao-Yu Lai🇨🇳 · Toshiki Maruyama🇯🇵 · Ren-Xin Xu🇨🇳 · En-Ping Zhou🇩🇪
Inspired by various astrophysical phenomenons, it is suggested that pulsar-like compact stars are comprised entirely of strangeons (quark-clusters with three-light-flavor symmetry) and a small amount of electrons. In order to better constrain the properties of strangeon stars, we propose a linked bag model to describe the condensed matter by the strong interaction (i.e., strong condensed matter) in both 2-flavoured (nucleons) and 3-flavoured (hyperons, strangeons, etc.) scenarios. The model parameters are calibrated to reproduce the saturation properties of nuclear matter, which are later applied to hyperon matter and strangeon matter. Compared with baryon matter, the derived energy per baryon of strangeon matter is reduced if the strangeon carries a large number of valence quarks, which stiffens the equation of state and consequently increases the maximum mass of strangeon stars. In a large parameter space, the maximum mass and tidal deformability of strangeon stars predicted by the linked bag model are consistent with the current astrophysical constraints. It is found that the maximum mass of strangeon stars can be as large as $\sim 2.5 M_{⊙}$ , while the tidal deformability of a $1.4 M_{⊙}$ strangeon star lies in the range of $180 ≲ Λ_{1.4} ≲ 340$ .
Subjects:
Nuclear Theory (nucl-th); High Energy Astrophysical Phenomena (astro-ph.HE)
arXiv:
2008.06932 [pdf]
IJMPE(2022)·25 citations
07
[Submitted on 17 Aug 2020]
Dibaryons: Molecular versus Compact Hexaquarks
H. Clement🇩🇪 · T. Skorodko🇩🇪
Hexaquarks constitute a natural extension of complex quark systems like also tetra- and pentaquarks do. To this end the current status of $d^{*} (2380)$ in both experiment and theory is shortly reviewed. Recent high-precision measurements in the nucleon-nucleon channel and analyses thereof have established $d^{*} (2380)$ as an indisputable resonance in the long-sought dibaryon channel. Important features of this $I (J^{P}) = 0 (3^{+})$ state are its narrow width and its deep binding relative to the $Δ (1232) Δ (1232)$ threshold. Its decay branchings favor theoretical calculations predicting a compact hexaquark nature of this state. We review the current status of experimental and theoretical studies on $d^{*} (2380)$ as well as new physics aspects it may bring in the future. In addition, we review the situation at the $Δ (1232) N$ and $N^{*} (1440) N$ thresholds, where evidence for a number of resonances of presumably molecular nature have been found -- similar to the situation in charmed and beauty sectors. Finally we briefly discuss the situation of dibaryon searches in the flavored quark sectors.
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Experiment (hep-ex); High Energy Physics — Phenomenology (hep-ph); Nuclear Experiment (nucl-ex)
arXiv:
2008.07200 [pdf]
CPC(2021)·28 citations
08
[Submitted on 17 Aug 2020]
Collective nuclear vibrations and initial state shape fluctuations in central Pb+Pb collisions: resolving the $v_{2}$ to $v_{3}$ puzzle
B.G. Zakharov🇷🇺
We have studied, for the first time, the influence of the collective quantum effects in the nuclear wave functions on the azimuthal anisotropy coefficients $ϵ_{2, 3}$ in the central Pb+Pb collisions at the LHC energies. With the help of the energy weighted sum rule we demonstrate that the classical treatment with the Woods-Saxon nuclear density overestimates the mean square quadrupole moment of the $^{208}$ Pb nucleus by a factor of $\sim 2.2$ . The Monte-Carlo Glauber simulation of the central Pb+Pb collisions accounting for the restriction on the quadrupole moment leads to $ϵ_{2} / ϵ_{3} \approx 0.8$ which allows to resolve the $v_{2}$ -to- $v_{3}$ puzzle.
Comments:
6 pages
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph)
arXiv:
2008.07304 [pdf]
JETP Lett.(2020)·10 citations
09
[Submitted on 14 Aug 2020] (cross-list from hep-ph)
Covariantizing Phase Space
Andrew J. Larkoski🇺🇸 · Tom Melia🇯🇵
We covariantize calculations over the manifold of phase space, establishing Stokes' theorem for differential cross sections and providing new definitions of familiar observable properties like infrared and collinear safety. Through the introduction of explicit coordinates and a metric we show phase space is isomorphic to the product space of a simplex and a hypersphere, and we identify geometric phenomena that occur when its dimensions are large. These results have implications for fixed order subtraction schemes, machine learning in particle physics and high-multiplicity heavy ion collisions.
Comments:
6 pages, 1 figure; v2: PRD version, extended discussion of IRC safe and additive observables from Stokes' theorem
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
2008.06508 [pdf]
PRD(2020)·24 citations
10
[Submitted on 14 Aug 2020] (cross-list from hep-lat)
P-Wave Two-Particle Bound and Scattering States in a Finite Volume including QED
Gianluca Stellin🇩🇪 · Ulf-G. Meißner🇩🇪
The mass shifts for two-fermion bound and scattering P-wave states subject to the long-range interactions due to QED in the non-relativistic regime are derived. Introducing a short range force coupling the spinless fermions to one unit of angular momentum in the framework of pionless EFT, we first calculate both perturbatively and non-perturbatively the Coulomb corrections to fermion-fermion scattering in the continuum and infinite volume context. Motivated by the research on particle-antiparticle bound states, we extend the results to fermions of identical mass and opposite charge. Second, we transpose the system onto a cubic lattice with periodic boundary conditions and we calculate the finite volume corrections to the energy of the lowest bound and unbound $T_{1}^{\pm}$ eigenstates. In particular, power law corrections proportional to the fine structure constant and resembling the recent results for S-wave states are found. Higher order contributions in $α$ are neglected, since the gapped nature of the momentum operator in the lattice environnement allows for a perturbative treatment of the QED interactions.
Comments:
73 pages, 7 figures, 0 tables. To be submitted to the European Physical Journal A
Subjects:
High Energy Physics — Lattice (hep-lat); Nuclear Theory (nucl-th)
arXiv:
2008.06553 [pdf]
EPJA(2021)·9 citations
11
[Submitted on 16 Aug 2020] (cross-list from hep-ph)
Determination of the masses and decay widths of the well-established $s$ and $p$ baryon resonances below $2$ GeV
Evangelos Matsinos
This study appertains to the extraction of estimates for the masses and for the partial decay widths to pion-nucleon final states of the well-established (four-star) $s$ and $p$ baryon resonances below $2$ GeV. These estimates are exclusively obtained from the data contained in the recent compilation by the Particle Data Group. Only the $N$ ( $S = 0, I = 1/2$ ) and the $Δ$ ( $S = 0, I = 3/2$ ) states are considered, where $S$ and $I$ denote strangeness and total isospin, respectively.
Comments:
17 pages
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
2008.06919 [pdf]
3 citations
12
[Submitted on 17 Aug 2020] (cross-list from hep-ph)
Triangle singularity as the origin of $X_{0} (2900)$ and $X_{1} (2900)$ observed in $B^{+} \to D^{+} D^{-} K^{+}$
Xiao-Hai Liu · Mao-Jun Yan🇨🇳 · Hong-Wei Ke · Gang Li🇨🇳 · Ju-Jun Xie🇨🇳
The LHCb collaboration reported the observation of a narrow peak in the $D^{-} K^{+}$ invariant mass distributions from the $B^{+} \to D^{+} D^{-} K^{+}$ decay. The peak is parameterized in terms of two resonances $X_{0} (2900)$ and $X_{1} (2900)$ with the quark contents $c ˉ s ˉ u d$ , and their spin-parity quantum numbers are $0^{+}$ and $1^{-}$ , respectively. We investigate the rescattering processes which may contribute to the $B^{+} \to D^{+} D^{-} K^{+}$ decays. It is shown that the $D^{*-} K^{*+}$ rescattering via the $χ_{c 1} K^{*+} D^{*-}$ loop or the $D ˉ_{1}^{0} K^{0}$ rescattering via the $D_{s J}^{+} D ˉ_{1}^{0} K^{0}$ loop simulate the $X_{0} (2900)$ and $X_{1} (2900)$ structures. Such phenomena are due to the analytical property of the scattering amplitudes with the triangle singularities located to the vicinity of the physical boundary.
Comments:
6 pages, 3 figures
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Experiment (hep-ex); Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
arXiv:
2008.07190 [pdf]
EPJC(2020)·92 citations
13
[Submitted on 17 Aug 2020] (cross-list from hep-ph)
Open charm and bottom tetraquarks in an extended relativized quark model
Qi-Fang Lü🇨🇳 · Dian-Yong Chen🇨🇳 · Yu-Bing Dong🇨🇳
In present work, we systematically calculate the mass spectra of open charm and bottom tetraquarks $q q q ˉ Q ˉ$ within an extended relativized quark model. The four-body relativized Hamiltonians including the Coulomb potential, confining potential, spin-spin interactions, and relativistic corrections are solved by using the variational method. It is found that the predicted masses of four $0^{+}$ $u d s ˉ c ˉ$ states are 2765, 3065, 3152, and 3396 MeV, which disfavor the assignment of the newly observed $X_{0} (2900)$ as a compact tetraquark. Moreover, the whole mass spectra of the open charm and bottom tetraquarks show quite similar patterns, which preserve the light flavor SU(3) symmetry and heavy quark symmetry well. In addition, our results suggest that the flavor exotic states $nn s ˉ c ˉ$ , $nn s ˉ b ˉ$ , $ss n ˉ c ˉ$ , and $ss n ˉ b ˉ$ and their antiparticles can be searched in the heavy-light meson plus kaon final states by future experiments. More theoretical and experimental efforts are needed to investigate these singly heavy tetraquarks.
Comments:
11 pages, 3 figures, comments and suggestions are welcome
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Experiment (hep-ex); Nuclear Theory (nucl-th)
arXiv:
2008.07340 [pdf]
PRD(2020)·79 citations
14
[Submitted on 17 Aug 2020] (cross-list from physics.atm-clus)
Efimov effect in non-integer dimensions induced by an external field
E. Garrido · A.S. Jensen
The Efimov effect can be induced by means of an external deformed one-body field that effectively reduces the allowed spatial dimensions to less than three. To understand this new mechanism, conceptually and practically, we employ a formulation using non-integer dimension, which is equivalent to the strength of an external oscillator field. The effect most clearly appears when the crucial two-body systems are unbound in three, but bound in two, dimensions. We discuss energy variation, conditions for occurrence, and number of Efimov states, as functions of the dimension. We use practical examples from cold atom physics of $^{133}$ Cs- $^{133}$ Cs- $^{133}$ Cs, $^{87}$ Rb- $^{87}$ Rb- $^{87}$ Rb, $^{133}$ Cs- $^{133}$ Cs- $^{6}$ Li, and $^{87}$ Rb- $^{87}$ Rb- $^{39}$ K. Laboratory tests of the effect can be performed with two independent parameters, i.e. the external one-body field and the Feshbach two-body tuning. The scaling and (dis)appearance of these Efimov states occur precisely as already found in three dimensions.
Comments:
6 pages, 5 figures. To be published in Physics Letters A
Subjects:
physics.atm-clus (physics.atm-clus); Quantum Gases (cond-mat.quant-gas); Nuclear Theory (nucl-th); Quantum Physics (quant-ph)
arXiv:
2008.07392 [pdf]
PLA(2021)·6 citations

Affiliations

first authorsco-authorsvia INSPIRE