Nuclear Theory·nucl-th

Friday·January 18, 2019

14 papers—6 primary·8 cross-listed

01
[Submitted on 16 Jan 2019]
A Study of Charge Radii and Neutron Skin Thickness near Nuclear Drip Lines
Virender Thakur · Shashi K Dhiman
We studied the charge radius, rms radius and neutron skin thickness $Δ r_{n p}$ in even-even isotopes of Si, S, Ar and Ca and isotones of N =20, 28, 50 and 82. The $Δ r_{n p}$ in doubly-magic $^{48}$ Ca, $^{68}$ Ni, $^{120, 132}$ Sn and $^{208}$ Pb nuclei has also been calculated. Theoretical calculations are done with the Hartree-Fock-Bogoliubov theory with the effective Skyrme interactions. Calculated theoretical estimates are in good agreement with the recently available experimental data. The charge radii for Si, S, Ar and Ca isotopes is observed to be minimum at neutron number N =14. The theoretically computed results with UNEDF0 model parameterization of functional are reasonably reproducing the experimental data for $Δ r_{n p}$ in $^{48}$ Ca, $^{68}$ Ni and $^{120, 132}$ Sn. The energy density functional of UNEDF1 model provides much improved result of $Δ r_{n p}$ for $^{208}$ Pb.
Subjects:
Nuclear Theory (nucl-th)
arXiv:
1901.05453 [pdf]
NPA(2019)·13 citations
02
[Submitted on 16 Jan 2019]
Optimizing the relativistic energy density functional with nuclear ground state and collective excitation properties
E. Yuksel · T. Marketin · N. Paar
We introduce a new relativistic energy density functional constrained by the ground state properties of atomic nuclei along with the isoscalar giant monopole resonance energy and dipole polarizability in $^{208}$ Pb. A unified framework of the relativistic Hartree-Bogoliubov model and random phase approximation based on the relativistic density-dependent point coupling interaction is established in order to determine the DD-PCX parameterization by $χ^{2}$ minimization. This procedure is supplemented with the co-variance analysis in order to estimate statistical uncertainties in the model parameters and observables. The effective interaction DD-PCX accurately describes the nuclear ground state properties including the neutron-skin thickness, as well as the isoscalar giant monopole resonance excitation energies and dipole polarizabilities. The implementation of the experimental data on nuclear excitations allows constraining the symmetry energy close to the saturation density, and the incompressibility of nuclear matter by using genuine observables on finite nuclei in the $χ^{2}$ minimization protocol, rather than using pseudo-observables on the nuclear matter, or by relying on the ground state properties only, as it has been customary in the previous studies.
Comments:
6 pages, 3 figures, submitted to Physical Review C
Subjects:
Nuclear Theory (nucl-th); Nuclear Experiment (nucl-ex)
arXiv:
1901.05552 [pdf]
PRC(2019)·81 citations
03
[Submitted on 17 Jan 2019]
New self-consistent mean field approximation and its application in strong interaction phase transition
Fei Wang🇨🇳 · Yakun Cao🇨🇳 · Yonghui Dia · Hongshi Zong🇨🇳
In this letter, taking the Nambu--Jona--Lasinio model as an example, we propose a new self-consistent mean field approximation method by means of Fierz transformation. This new self-consistent mean field approximation introduces a new free parameter $α$ to be determined by experiments and when $α$ takes 0.5, it reduces to the mean field approximation that was commonly used in the past. Then based on this self-consistent mean field approximation, we study the influence of the undetermined parameter $α$ on the phase diagram of the two-flavor strong interaction matter. It is found that the value of $α$ plays an extremely important role in the study of strong interaction phase diagram. It not only changes the position of the phase transition point of strong interaction matter, but also affects the order of phase transition, for example, when $α$ is greater than the critical value $α_{c} = 0.71$ , then the strong interaction matter phase diagram no longer exists critical end point. In addition, in the case of zero temperature and finite density, we also found that when $α$ is greater than 1.044, the pseudo-critical chemical potential is about 4 $\sim$ 5 times the saturation density of the nuclear matter, which agrees with the expected results from the image of hadrons degree of freedom. The resulting equations of state of strong interaction matter at low temperatures and high densities will have an important impact on the study of the mass radius relationship of neutron stars and the merging process of binary neutron stars.
Comments:
5 pages, 3 figures
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph)
arXiv:
1901.05601 [pdf]
CPC(2019)·29 citations
04
[Submitted on 17 Jan 2019]
Unified Coupled-Channels and Hauser-Feshbach Model Calculation for Nuclear Data Evaluation
Toshihiko Kawano🇺🇸
We present an overview of the coupled-channels optical model and the Hauser-Feshbach theory code CoH $_{3}$ , which focuses on the nuclear reaction calculations in the keV to tens of MeV region with special attention to the nuclear deformation. The code consists of three major sections that undertake the one-body potential mean-field theory, the coupled-channels optical model, and the Hauser-Feshbach statistical decay. There are other complementary segments to perform the whole nuclear reaction calculations, such as the direct/semidirect radiative capture process, pre-equilibrium process, and prompt fission neutron emission.
Subjects:
Nuclear Theory (nucl-th)
arXiv:
1901.05641 [pdf]
20 citations
05
[Submitted on 17 Jan 2019]
Computation of products of phase space factors and nuclear matrix elements for the Double Beta Decay
Sabin Stoica🇷🇴
The nuclear matrix elements (NME) and phase space factors (PSF) entering the half-life formulas of the double-beta decay (DBD) process are two key quantities whose accurate computation still represents a challenge. In this paper we propose a new approach of calculating them, namely to compute directly their product as an unique formula. This procedure allows a more coherent treatment of the nuclear approximations and input parameters appearing in both quantities and avoids possible confusion in interpreting the DBD data due to different individual expressions adopted for PSF and NME (and consequently their reporting in different units) by different authors. Our calculations are performed for both two neutrino ( $2 ν β β$ ) and neutrinoless ( $0 ν β β$ ) decay modes, and for five nuclei of most experimental interest. Further, using the most recent experimental limits for $0 ν β β$ decay half-lives, we provide new constraints on the light mass neutrino parameter. Finally, by separating in the half-lives formulas the factor representing the axial-vector constant to the forth, we advance suggestions on how to reduce the errors introduced in calculation by the uncertain value of this constant by exploiting the DBD data from different isotopes and/or decay modes.
Comments:
6 pages, 2 tables, accepted at Chinese Physics C
Subjects:
Nuclear Theory (nucl-th)
arXiv:
1901.05718 [pdf]
CPC(2019)·4 citations
06
[Submitted on 17 Jan 2019]
Structural properties and decay modes of Z $=$ 122, 120 and 118 superheavy nuclei
G. Saxena · M. Kumawat · S. Somorendro Singh · Mamta Aggarwal
Structural properties and the decay modes of the superheavy elements Z $=$ 122, 120, 118 are studied in a microscopic framework. We evaluate the binding energy, one- and two- proton and neutron separation energy, shell correction and density profile of even and odd isotopes of Z $=$ 122, 120, 118 (284 $\leq$ A $\leq$ 352) which show a reasonable match with FRDM results and the available experimental data. Equillibrium shape and deformation of the superheavy region are predicted. We investigate the possible decay modes of this region specifically $α$ -decay, spontaneous fission (SF) and the $β$ -decay and evaluate the probable $α$ -decay chains. The phenomena of bubble like structure in the charge density is predicted in $^{330}$ 122, $^{292, 328}$ 120 and $^{326}$ 118 with significant depletion fraction around 20-24 $%$ which increases with increasing Coulomb energy and diminishes with increasing isospin (N $-$ Z) values exhibiting the fact that the coloumb forces are the main driving force in the central depletion in superheavy systems.
Comments:
18 pages, 7 figures
Subjects:
Nuclear Theory (nucl-th)
arXiv:
1901.05926 [pdf]
IJMPE(2019)·18 citations
07
[Submitted on 16 Jan 2019] (cross-list from hep-lat)
Calculation of Nucleon Electric Dipole Moments Induced by Quark Chromo-Electric Dipole Moments and the QCD $θ$ -term
S. Syritsyn🇺🇸 · T. Izubuchi🇺🇸 · H. Ohki🇺🇸
Electric dipole moments (EDMs) of nucleons and nuclei, which are sought as evidence of CP violation, require lattice calculations to connect constraints from experiments to limits on the strong CP violation within QCD or CP violation introduced by new physics from beyond the standard model. Nucleon EDM calculations on a lattice are notoriously hard due to large statistical noise, chiral symmetry violating effects, and potential mixing of the EDM and the anomalous magnetic moment of the nucleon. In this report, details of ongoing lattice calculations of proton and neutron EDMs induced by the QCD $θ$ -term and the quark chromo-EDM, the lowest-dimension effective CP-violating quark-gluon interaction are presented. Our calculation employs chiral-symmetric fermion discretization. An assessment of feasibility of nucleon EDM calculations at the physical point is discussed.
Comments:
proceedings XIIIth Quark Confinement and Hadron Spectrum conference (Maynooth University, Ireland, July 31-August 6, 2018); 11 pages, 13 figures. arXiv admin note: substantial text overlap with arXiv:1810.03721
Subjects:
High Energy Physics — Lattice (hep-lat); High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
1901.05455 [pdf]
PoS(2019)·18 citations
08
[Submitted on 16 Jan 2019] (cross-list from hep-ph)
Narrow exotic hadrons in the heavy quark limit of QCD
Yiming Cai🇺🇸 · Thomas Cohen🇺🇸
This paper focuses on tetraquarks containing two heavy quarks in the formal limit where the heavy quark masses are taken to be arbitrarily large. There are well-established model-independent arguments for the existence of deeply bound exotic $q ˉ q ˉ^{'} QQ$ tetraquark in the formal limit of arbitrarily large heavy quark masses. However, these previous arguments did not address the question whether tetraquark states exist close to the threshold for breaking up into two heavy mesons. Such states are not stable under strong interactions---they can emit pions and decay to lower-lying tetraquark states. This raises the issue of whether the nature of the heavy quark limit requires such states to exist as resonances that are narrow. Here we present a model-independent argument that establishes the existence of parametrically narrow tetraquark states. The argument here is based on Born-Oppenheimer and semi-classical considerations. The results derived here are only valid in a formal limit that is well outside the regime occurring for charm quarks in nature. However the analysis may give some insight in the experimentally observed narrow near-threshold tetraquark states containing a heavy quark and antiquark.
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
1901.05473 [pdf]
EPJA(2019)·7 citations
09
[Submitted on 16 Jan 2019] (cross-list from hep-ph)
Multi-particle potentials from light-like Wilson lines in quark-gluon plasmas: a generalized relation of in-medium splitting rates to jet-quenching parameters $q^$
Peter Arnold🇺🇸
A powerful historical insight about the theory of in-medium showering in QCD backgrounds was that splitting rates can be related to a parameter $q^$ that characterizes the rate of transverse-momentum kicks to a high-energy particle from the medium. Another powerful insight was that $q^$ can be defined (with caveats) even when the medium is strongly coupled, using long, narrow Wilson loops whose two long edges are light-like Wilson lines. The medium effects for the original calculations of in-medium splitting rates can be formulated in terms of 3-body imaginary-valued `potentials' that are defined with three long, light-like Wilson lines. Corrections due to overlap of two consecutive splittings can be calculated using similarly defined 4-body potentials. I give a simple argument for how such $N$ -body potentials can be determined in the appropriate limit just from knowledge of the values of $q^$ for different color representations. For $N > 3$ , the $N$ -body potentials have non-trivial color structure, which will complicate calculations of overlap corrections outside of the large- $N_{c}$ or soft bremsstrahlung limits.
Comments:
20 pages, 8 figures. Difference from v2: correction (which does not propagate) to eq. (2.16)
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
1901.05475 [pdf]
PRD(2019)·12 citations
10
[Submitted on 16 Jan 2019] (cross-list from hep-th)
Simple non-perturbative resummation schemes beyond mean-field: case study for scalar $ϕ^{4}$ theory in 1+1 dimensions
Paul Romatschke🇺🇸
I present a sequence of non-perturbative approximate solutions for scalar $ϕ^{4}$ theory for arbitrary interaction strength, which contains, but allows to systematically improve on, the familiar mean-field approximation. This sequence of approximate solutions is apparently well-behaved and numerically simple to calculate since it only requires the evaluation of (nested) one-loop integrals. To test this resummation scheme, the case of $ϕ^{4}$ theory in 1+1 dimensions is considered, finding approximate agreement with known results for the vacuum energy and mass gap up to the critical point. Because it can be generalized to other dimensions, fermionic fields and finite temperature, the resummation scheme could potentially become a useful tool for calculating non-perturbative properties approximately in certain quantum field theories.
Comments:
v1: 12 pages plus appendix, one figure; v2: matches published version; v3: minor typos corrected
Subjects:
High Energy Physics — Theory (hep-th); Statistical Mechanics (cond-mat.stat-mech); High Energy Physics — Lattice (hep-lat); Nuclear Theory (nucl-th)
arXiv:
1901.05483 [pdf]
JHEP(2019)·32 citations
11
[Submitted on 17 Jan 2019] (cross-list from nucl-ex)
Measurement of directed flow of $D^{0}$ and $D^{0} ˉ$ mesons in 200 GeV Au+Au collisions at RHIC using the STAR detector
Liang He (for the STAR Collaboration)🇺🇸
Charm quarks, owing to their large mass, are produced predominantly in the initial hard scatterings in heavy-ion collisions, and therefore can be a valuable tool for studying the early time dynamics of these collisions. The rapidity-odd directed flow at mid-rapidity in heavy-ion collisions originates from a tilt in the reaction plane of the thermalized medium caused by the asymmetry between the number of participants from projectile and target nuclei as a function of rapidity. Recently, it has been predicted that the slope of the directed flow at mid-rapidity for $D^{0}$ mesons, arising from the transport of charm quarks in the tilted medium, can be several times larger than that of light flavor hadrons. The magnitude of the slope is expected to be sensitive to the magnitude of the tilt and the charm quark drag coefficient in the medium. It has also been predicted that the transient electromagnetic field generated at early time can induce a much larger directed flow for heavy quarks than for light quarks. In these proceedings, we will report on the first measurement of the directed flow for the $D^{0}$ and $D ˉ^{0}$ mesons as a function of rapidity in Au+Au collisions at $s_{_{NN}}$ = 200 GeV using high statistics data collected with the Heavy Flavor Tracker in 2014 and 2016 RHIC runs.
Comments:
5 pages, 3 figures. Submitted in Hard Probes 2018 proceedings
Subjects:
Nuclear Experiment (nucl-ex); High Energy Physics — Experiment (hep-ex); High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
1901.05622 [pdf]
PoS(2019)·3 citations
12
[Submitted on 17 Jan 2019] (cross-list from hep-ph)
$Ω N N$ and $ΩΩ N$ states
H. Garcilazo🇲🇽 · A. Valcarce🇪🇸
The lattice QCD analysis of the HAL QCD Collaboration has recently derived $Ω N$ and $ΩΩ$ interacting potentials with nearly physical quark masses ( $m_{π} ≃$ 146 MeV and $m_{K} ≃$ 525 MeV). They found an attractive interaction in the $Ω N$ $^{5} S_{2}$ channel which supports a bound state with a central binding energy of 1.54 MeV. The $ΩΩ$ $^{1} S_{0}$ channel shows an overall attraction with a bound state with a central binding energy of 1.6 MeV. In this paper we looked closely at the $Ω N N$ and $ΩΩ N$ three-body systems making use of the latest HAL QCD Collaboration $Ω N$ and $ΩΩ$ interactions. Our results show that the $Ω d$ system in the state with maximal spin $(I) J^{P} = (0) 5/ 2^{+}$ is bound with a binding energy of about 20 MeV. The $(I) J^{P} = (1) 3/ 2^{+}$ $Ω nn$ state presents a resonance decaying to $ΛΞ n$ and $ΣΞ n$ , with a separation energy of $\sim$ 1 MeV. The $(I) J^{P} = (1/2) 1/ 2^{+}$ $ΩΩ N$ state also exhibits a resonance decaying to $ΛΞΩ$ and $ΣΞΩ$ , with a separation energy of $\sim$ 4.6 MeV. We have calculated the contribution of the Coulomb potential to differentiate among the different charged states.
Comments:
14 pages. Accepted for publication in Phys. Rev. C
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
1901.05678 [pdf]
PRC(2019)·24 citations
13
[Submitted on 17 Jan 2019] (cross-list from nucl-ex)
Experimental Evidence for Transverse Wobbling in $^{105}$ Pd
J. Timár🇭🇺 · Q. B. Chen🇩🇪 · B. Kruzsicz🇭🇺 · D. Sohler🇭🇺 · I. Kuti🇭🇺 · S. Q. Zhang🇨🇳 · J. Meng🇨🇳 · P. Joshi🇬🇧 · R. Wadsworth🇬🇧 · K. Starosta🇨🇦 · A. Algora🇭🇺 · P. Bednarczyk🇵🇱 and 16 other authors
New rotational bands built on the $ν$ $(h_{11/2})$ configuration have been identified in $^{105}$ Pd. Two bands built on this configuration show the characteristics of transverse wobbling: the $Δ$ $I$ =1 transitions between them have a predominant E2 component and the wobbling energy decreases with increasing spin. The properties of the observed wobbling bands are in good agreement with theoretical results obtained using constrained triaxial covariant density functional theory and quantum particle rotor model calculations. This provides the first experimental evidence for transverse wobbling bands based on a one-neutron configuration, and also represents the first observation of wobbling motion in the $A$ $\sim$ 100 mass region.
Subjects:
Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
arXiv:
1901.05891 [pdf]
PRL(2019)·73 citations
14
[Submitted on 17 Jan 2019] (cross-list from hep-ph)
Superheavy objects composed of nuclear and dark matter
Vakhid A. Gani🇷🇺 · Maxim Yu. Khlopov🇷🇺 · Dmitry N. Voskresensky🇷🇺
We consider a model of $O$ He atomic dark matter formed by Coulomb binding of the hypothetical stable double-charged massive $O^{--}$ particles with nuclei of primordial helium. Such a dark matter can be captured by ordinary matter forming superheavy nuclei. We propose a possibility of self-bound by nuclear and electromagnetic interaction $O$ -nuclearites as well as more massive gravitating ones and discuss effect of accumulation of $O$ He atoms in stars and their effect in stellar evolution.
Comments:
4 pages; Proceedings of the 4th International Conference on Particle Physics and Astrophysics (ICPPA-2018), Moscow, 22-26 October 2018
Subjects:
High Energy Physics — Phenomenology (hep-ph); Cosmology and Nongalactic Astrophysics (astro-ph.CO); Nuclear Theory (nucl-th)
arXiv:
1901.05930 [pdf]
J.Phys.Conf.Ser.(2019)·0 citations

Affiliations

first authorsco-authorsvia INSPIRE