Nuclear Theory·nucl-th

Tuesday·November 9, 2021

14 papers—6 primary·8 cross-listed

01
[Submitted on 8 Nov 2021]
Dynamic effects of nuclear surface in isoscalar dipole modes
V. I. Abrosimov · O. I. Davydovska
Dynamic surface effects in the isoscalar dipole modes of heavy nuclei are studied within a semiclassical model based on the solution of the Vlasov kinetic equation for finite Fermi systems with a moving surface. In order to clarify the role of dynamic surface effects we have considered an approximate solution, which takes into account only the part of the variation of the phase-space distribution function caused by the dynamic surface (the dynamic-surface approximation). It is shown that the dynamic surface effects have an essential influence on the features of the isoscalar dipole modes. The isoscalar dipole strength function has a two-resonance structure already in the dynamic-surface approximation, and the centroid energies of both the low-energy resonance and the high-energy resonance are close to corresponding centroid energies of exact strength function. Calculations of the velocity field in the dynamic-surface approximation show the vortex character of the low-energy isoscalar dipole resonance and the compression character of the high-energy one.
Comments:
15 pages, 4 figures, typos correct
Subjects:
Nuclear Theory (nucl-th)
arXiv:
2111.04218 [pdf]
NPA(2023)·0 citations
02
[Submitted on 8 Nov 2021]
Dineutron in the $2_{1}^{+}$ state of $^{6}$ He
Shoya Ogawa · Takuma Matsumoto
We investigate the dineutron in the $2_{1}^{+}$ state of $^{6}$ He via analysis of its decay mode by using the complex scaling method. In this letter, we propose the cross section for the resonant state to distinguish the resonant contributions from the nonresonant ones. As the results, it is found that the shoulder peak appears in the cross section for the resonant state as a function of $ε_{n - n}$ . Furthermore, we show that the $S$ = 0 component of the cross section, where $S$ is the total spin of the valence two neutrons, has a peak around the shoulder peak, which comes from the dineutron configuration in the $2_{1}^{+}$ state. Thus we conclude that the shoulder peak is expected to indicate the existence of the dineutron in the $2_{1}^{+}$ state.
Subjects:
Nuclear Theory (nucl-th); Nuclear Experiment (nucl-ex)
arXiv:
2111.04285 [pdf]
PRC(2022)·2 citations
03
[Submitted on 8 Nov 2021]
Can we decipher the composition of the core of a neutron star?
Chiranjib Mondal🇫🇷 · Francesca Gulminelli🇫🇷
General relativity guarantees a unique one-to-one correspondence between static observables of neutron stars (NSs) accessible by multi-messenger astronomy, such as mass-radius or tidal deformability, and the equation of state (EoS) of beta equilibrated matter. It is well known that these static properties are not enough to discern conventional NSs from hybrid stars. However, if one assumes that hadrons present in the neutron star core are only neutrons and protons, the lepton fraction is in principle determined unequivocally by the condition of chemical equilibrium. Using a simple analytical method based on a polynomial expansion of the EoS, we show that multiple solutions are possible to the beta-equilibrium equation, leading to a characteristic indetermination on the composition of the interiors of NSs, even in the purely nucleonic hypothesis. We further show that additional empirical information on symmetric matter at high densities are not very efficient to pin down the composition, if uncertainties on measurements are accounted for. We conclude that constraints on the symmetry energy at high densities only, can make meaningful impact to decipher the composition of neutron star core. Our results give a lower limit to the uncertainty on the NS core composition that can be obtained with astrophysical and terrestrial experiments.
Comments:
8 pages, restructured, new figures added
Subjects:
Nuclear Theory (nucl-th); High Energy Astrophysical Phenomena (astro-ph.HE); Nuclear Experiment (nucl-ex)
arXiv:
2111.04520 [pdf]
PRD(2022)·42 citations
04
[Submitted on 8 Nov 2021]
Systematic shell-model study on spectroscopic properties in the south region of $^{208}$ Pb
Cenxi Yuan · Menglan Liu · Noritaka Shimizu · Zs. Podolyak · Toshio Suzuki · Takaharu Otsuka · Zhong Liu
We aim to study the properties of nuclei in the south region of $^{208}$ Pb systematically, including the binding and excitation energies and electromagnetic properties, in order to predict unknown properties of these nuclei, such as isomerism, utilizing a theoretical model which describes the experimentally known properties precisely. We also address whether the $N = 126$ shell closure is robust or not when the proton number decreases from $^{208}$ Pb. We performed large-scale shell-model calculations with a new Hamiltonian suggested in the present work. The model space is taken as the five proton orbits within $50 < Z ⩽ 82$ and the thirteen neutron orbits within $82 < N ⩽ 184$ . And one-particle one-hole excitation is allowed across the $N = 126$ gap. The Hamiltonian is constructed by combining the existing Hamiltonians, KHHE (with adjustment of its proton-proton part) and KHPE, and the monopole based universal interaction. The shell-model results well reproduce the experimentally observed binding energies and spectroscopic properties, such as isomerism, core excitation, and electromagnetic properties. Some possible isomeric states in neutron-rich Pb, Tl, and Hg isotopes are predicted with transition energies and half-lives. We also examine the effective charges and the quenching of the $g$ factors suitable for this region by systematic comparisons between observed and calculated electromagnetic properties. A new Hamiltonian is constructed for nuclei in the south region of $^{208}$ Pb, mainly including Pb, Tl, Hg, Au, Pt, Ir, Os, Re, and W isotopes around $N = 126$ , and provides them reasonable descriptions on nuclear properties including binding energies, excitation energies and electromagnetic properties through comprehensive and systematic studies.
Subjects:
Nuclear Theory (nucl-th); Nuclear Experiment (nucl-ex)
arXiv:
2111.04537 [pdf]
PRC(2022)·24 citations
05
[Submitted on 8 Nov 2021]
Self-consistent description of high-spin states in doubly magic $^{208}$ Pb
N. Lyutorovich · V. Tselyaev · J. Speth · G. Martinez-Pinedo · K. Langanke · P.-G. Reinhard
We analyze recent data on a long series of high-spin states in $^{208}$ Pb with a self-consistent phonon-coupling model for nuclear excitations based on the Skyrme functionals. The model is the renormalized time-blocking approximation (RenTBA) which takes the coherent one-particle-one-hole (1p1h) states of the random-phase approximation (RPA) as starting point and develops from that more complex configurations beyond RPA. To the best of our knowledge, this is the first investigation of high spin states in $^{208}$ Pb using self-consistent nuclear models. The interesting point here is that complex configurations are compulsory to describe the upper end of the long spin series at all. The data thus provide an ideal testing ground for phonon-coupling models as they give direct access to complex configurations. We find that standard Skyrme functionals which perform well in ground state properties and giant resonance excitations deliver at once an agreeable description of these high spin states.
Comments:
7 pages, 2 figures
Subjects:
Nuclear Theory (nucl-th)
arXiv:
2111.04602 [pdf]
PRC(2022)·1 citation
06
[Submitted on 8 Nov 2021]
Nuclear DFT analysis of electromagnetic moments in odd near doubly magic nuclei
P.L. Sassarini🇬🇧 · J. Dobaczewski🇬🇧 · J. Bonnard🇬🇧 · R.F. Garcia Ruiz🇺🇸
We use the nuclear density functional theory to determine nuclear electric quadrupole and magnetic dipole moments in all one-particle and one-hole neighbours of eight doubly magic nuclei. We align angular momenta along the intrinsic axial-symmetry axis with broken time-reversal symmetry, which allows us to explore fully the self-consistent charge, spin, and current polarisation. Spectroscopic moments are determined for symmetry-restored wave functions and compared with available experimental data. We find that the obtained polarisations do not call for using quadrupole- or dipole-moment operators with effective charges or effective g-factors.
Comments:
16 LaTeX pages, 6 figures, extended version, accepted as a Letter in Journal of Physics G
Subjects:
Nuclear Theory (nucl-th)
arXiv:
2111.04675 [pdf]
J.Phys.G(2022)·29 citations
07
[Submitted on 5 Nov 2021] (cross-list from hep-ph)
Transverse momentum dependent distributions in dijet and heavy hadron pair production at EIC
Rafael F. del Castillo🇪🇸 · Miguel G. Echevarria🇪🇸 · Yiannis Makris🇮🇹 · Ignazio Scimemi🇪🇸
We discuss the measurement of gluon transverse momentum distribution (TMD) in dijet and heavy hadron pair (HHP) production in semi-inclusive deep inelastic scattering. The factorization of these processes in impact parameter space shows the appearance of a specific new soft factor matrix element on top of angular a complex valued anomalous dimensions. We show in detail how these features can be treated consistently and we discuss a scale prescription for the evolution kernel of the dijet soft function. As a result we obtain phenomenological predictions for unpolarized and angular modulated cross-sections for the electron-ion collider (EIC) using current available information on unpolarized TMD.
Comments:
29 pages, 7 figures
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Experiment (hep-ex); Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
arXiv:
2111.03703 [pdf]
JHEP(2022)·30 citations
08
[Submitted on 6 Nov 2021] (cross-list from hep-ph)
Thermal production of sexaquarks in heavy-ion collisions
D. Blaschke (1 and 2 and 3)🇵🇱 · Larissa Bravina (4)🇳🇴 · Kyrill Bugaev (5 and 6)🇺🇦 · Glennys R. Farrar (7)🇺🇸 · Boris Grinyuk (5)🇺🇦 · Oleksii Ivanytskyi (1 and 5)🇵🇱 · Sonia Kabana (8)🇨🇱 · Sergey V. Kuleshov (9 and 10)🇨🇱 · Irina K. Potashnikova (11)🇨🇱 · Violetta Sagun (12 and 5)🇺🇦 · Arkadiy Taranenko (3)🇷🇺 · Oleksandr V. Vitiuk (6)🇺🇦 and 3 other authors
We present new results on the thermal production yield of a hypothetical state made of six quarks $uu dd ss$ assuming its production in heavy-ion collisions at the CERN LHC. A state with this quark content and mass low enough to be stable against decay in timescales of the order of the age of the Universe, has been hypothesized by one of us (G.F.) and has been discussed as a possible dark matter candidate. In this work we address for the first time the thermal production rate that can be expected for this state in heavy-ion collisions at colliders. For this estimate we use a thermal model which has been shown to describe accurately the production of hadrons and nuclei in heavy-ion collisions at LHC energy. This estimate is of great relevance for sexaquark searches at colliders as well as for its consideration as a dark matter candidate and for the composition of neutron stars.
Comments:
11 pages, 2 figures
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
2111.03770 [pdf]
Int.J.Mod.Phys.A(2021)·6 citations
09
[Submitted on 6 Nov 2021] (cross-list from nucl-ex)
Perspectives in Small Systems : Heavy Quarks and HBT Radii
Debasish Das🇮🇳
Recent observations of QGP-like phenomena in small collision systems like p+p and p+A collisions have questioned our understanding of the basic paradigms of high energy heavy-ion physics. A brief discussion of these new aspects in small systems which in turn influence our understanding of hard probes like heavy quarks has been provided. Furthermore, a closer observation of the two-particle Hanbury-Brown Twiss (HBT) interferometry measurements provide new insights in our understanding of medium-like phenomena in small systems. An outlook of future goals and measurements is also made.
Comments:
Published in Nuclear Physics, Section A, 2021
Subjects:
Nuclear Experiment (nucl-ex); High Energy Physics — Experiment (hep-ex); High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
2111.03926 [pdf]
NPA(2021)·4 citations
10
[Submitted on 8 Nov 2021] (cross-list from astro-ph.HE)
The effect of the energy functional on the pasta-phase properties of catalysed neutron stars
H. Dinh Thi🇫🇷 · A. F. Fantina🇫🇷 · F. Gulminelli🇫🇷
Nuclear pasta, that is an inhomogeneous distribution of nuclear matter characterised by non-spherical clustered structures, is expected to occur in a narrow spatial region at the bottom of the inner crust of neutron stars, but the width of the pasta layer is strongly model dependent. In the framework of a compressible liquid-drop model, we use Bayesian inference to analyse the constraints on the sub-saturation energy functional and surface tension imposed by both ab-initio chiral perturbation theory calculations and experimental measurements of nuclear masses. The posterior models are used to obtain general predictions for the crust-pasta and pasta-core transition with controlled uncertainties. A correlation study allows extracting the most influential parameters for the calculation of the pasta phases. The important role of high-order empirical parameters and the surface tension is underlined.
Comments:
15 pages, 11 figures. Contribution to the EPJ A topical issue "CompOSE: a repository for Neutron Star Equations of State and Transport Properties"
Subjects:
High Energy Astrophysical Phenomena (astro-ph.HE); Nuclear Theory (nucl-th)
arXiv:
2111.04374 [pdf]
EPJA(2021)·27 citations
11
[Submitted on 8 Nov 2021] (cross-list from hep-ph)
Initial-state temperature of light meson emission source from squared momentum transfer spectra in high-energy collisions
Qi Wang🇨🇳 · Fu-Hu Liu🇨🇳 · Khusniddin K. Olimov🇺🇿
The squared momentum transfer spectra of light mesons, $π^{0}$ , $π^{+}$ , $η$ , and $ρ^{0}$ , produced in high-energy virtual photon-proton ( $γ^{*} p$ ) $\to meson + nucleon$ process in electron-proton ( $e p$ ) collisions measured by the CLAS Collaboration are analyzed by the Monte Carlo calculations, where the transfer undergoes from the incident $γ^{*}$ to emitted meson or equivalently from the target proton to emitted nucleon. In the calculations, the Erlang distribution from a multi-source thermal model is used to describe the transverse momentum spectra of emitted particles. Our results show that the average transverse momentum ( $⟨ p_{T} ⟩$ ) and the initial-state temperature ( $T_{i}$ ) increase from lower squared photon virtuality ( $Q^{2}$ ) and Bjorken variable ( $x_{B}$ ) to higher one. This renders that the excitation degree of emission source, which is described by $⟨ p_{T} ⟩$ and $T_{i}$ , increases with increasing of $Q^{2}$ and $x_{B}$ .
Comments:
17 pages, 6 figures. Frontiers in Physics, accepted
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Experiment (hep-ex); Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
arXiv:
2111.04486 [pdf]
Front.in Phys.(2021)·13 citations
12
[Submitted on 8 Nov 2021] (cross-list from hep-ph)
New hadron configuration: The double-gluon hybrid state
Hua-Xing Chen🇨🇳 · Wei Chen🇨🇳 · Shi-Lin Zhu🇨🇳
This is the first study on the double-gluon hybrid, which consists of one valence quark and one valence antiquark together with two valence gluons. We concentrate on the one with the exotic quantum number $J^{P C} = 2^{+-}$ that conventional $q ˉ q$ mesons can not reach. We apply QCD sum rule method to evaluate its mass to be $2.2 6_{- 0.25}^{+ 0.20}$ GeV, and study its possible decay patterns. Especially, its three-meson decay patterns are generally not suppressed severely compared to two-meson decay patterns, so the $S$ -wave three-meson decay channels $f_{1} ω π / f_{1} ρ π$ can be useful in identifying its nature, which is of particular importance to the direct test of QCD in the low energy sector.
Comments:
5 pages, 3 figures, 1 table, revised version to be published in PRD
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Experiment (hep-ex); High Energy Physics — Lattice (hep-lat); Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
arXiv:
2111.04514 [pdf]
PRD(2022)·16 citations
13
[Submitted on 8 Nov 2021] (cross-list from hep-ph)
Explaining the Cabibbo Angle Anomaly
Claudio Andrea Manzari🇨🇭
The Cabibbo-Cobayashi-Maskawa (CKM) matrix parametrizes the misalignement between the up- and down-quark mass basis in the Standard Model (SM). The observation of first row CKM unitarity violation has recently emerged as a new anomaly of the SM, known as the "Cabibbo Angle Anomaly" (CAA). With current measurements, comparing the elements $V_{u d}$ and $V_{u s}$ extracted from beta and kaon decays respectively, the tension with the SM prediction amounts to $\sim$ $3 σ$ . Recently, it has been pointed out that this anomaly can also be seen as a discrepancy in the determination of the Fermi constant from muon decay vs $β$ and K decays, once CKM unitarity is assumed. In fact, possible explanations in terms on New Physics fall under two broad classes: contributions to $β$ decay and/or to $μ$ decay. In this proceedings, we discuss these solutions in terms of gauge invariant dimension 6 operators in SMEFT and simplified extensions of the Standard Model. The latter could introduce correlations with other anomalies in the SM, pointing to new and interesting directions for model building.
Comments:
7 pages, 1 figure, contribution to The European Physical Society Conference on High Energy Physics 2021 (EPS-HEP2021)
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Experiment (hep-ex); Nuclear Theory (nucl-th)
arXiv:
2111.04519 [pdf]
PoS(2022)·3 citations
14
[Submitted on 8 Nov 2021] (cross-list from hep-lat)
Overview of lattice calculations of the $x$ -dependence of PDFs, GPDs and TMDs
Krzysztof Cichy🇵🇱
For a long time, lattice QCD was unable to address the $x$ -dependence of partonic distributions, direct access to which is impossible in Euclidean spacetime. Recent years have brought a breakthrough for such calculations when it was realized that partonic light-cone correlations can be accessed through spatial correlations computable on the lattice. Appropriately devised observables can be factorized into physical PDFs via a perturbative procedure called matching, analogous to the standard factorization of experimental cross sections. In this short review, aimed at a broader high-energy and nuclear physics community, we discuss the recent highlights of this research program. Key concepts are outlined, followed by a case study illustrating the typical stage of current lattice extractions and by a brief review of the most recent explorations. We finalize with a number of messages for the prospects of lattice determinations of partonic structure.
Comments:
12 pages, 2 figures; invited plenary talk at the Virtual Tribute to Quark Confinement and the Hadron Spectrum 2021, August 2-6, 2021
Subjects:
High Energy Physics — Lattice (hep-lat); High Energy Physics — Experiment (hep-ex); High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
2111.04552 [pdf]
EPJ Web Conf.(2022)·40 citations

Affiliations

first authorsco-authorsvia INSPIRE