Nuclear Theory·nucl-th

Tuesday·October 1, 2019

19 papers—11 primary·8 cross-listed

01
[Submitted on 26 Sept 2019]
Insights into the Origin of Mass
Craig D. Roberts🇨🇳
Atomic nuclei are the core of everything we can see. At the first level of approximation, their atomic weights are simply the sum of the masses of all the nucleons they contain. Each nucleon has a mass $m_{N} \approx 1$ GeV, i.e. approximately 2000-times the electron mass. The Higgs boson produces the latter, but what produces the nucleon mass? This is the crux: the vast bulk of the mass of a nucleon is lodged with the energy needed to hold quarks together inside it; and that is supposed to be explained by quantum chromodynamics (QCD), the strong-interaction piece within the Standard Model. This contribution canvasses the potential for a coherent effort in QCD phenomenology and theory, coupled with experiments at existing and planned facilities, to reveal the origin and distribution of mass by focusing on the properties of the strong-interaction Nambu-Goldstone modes. Key experiments are approved at JLab 12; planned with COMPASS++/AMBER at CERN; and could deliver far-reaching insights by exploiting the unique capabilities foreseen at an electron ion collider.
Comments:
9 pages, 4 figures. Summary of a plenary presentation at "INPC 2019 - 27th International Nuclear Physics Conference", Glasgow, UK, 29 July to 2 August, 2019. arXiv admin note: substantial text overlap with arXiv:1909.11102
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Lattice (hep-lat); High Energy Physics — Phenomenology (hep-ph); Nuclear Experiment (nucl-ex)
arXiv:
1909.12832 [pdf]
J.Phys.Conf.Ser.(2020)·11 citations
02
[Submitted on 27 Sept 2019]
Regularized pseudopotential for mean-field calculations
K. Bennaceur🇫🇷 · J. Dobaczewski🇬🇧 · T. Haverinen🇫🇮 · M. Kortelainen🇫🇮
We present preliminary results obtained with a finite-range two-body pseudopotential complemented with zero-range spin-orbit and density-dependent terms. After discussing the penalty function used to adjust parameters, we discuss predictions for binding energies of spherical nuclei calculated at the mean-field level, and we compare them with those obtained using the standard Gogny D1S finite-range effective interaction.
Comments:
6 pages, 2 figures, contribution to the conference proceedings for INPC 2019 (Glasgow)
Subjects:
Nuclear Theory (nucl-th)
arXiv:
1909.12879 [pdf]
J.Phys.Conf.Ser.(2020)·1 citation
03
[Submitted on 28 Sept 2019]
Finite-range separable pairing interaction in Cartesian coordinates
A.M. Romero · J. Dobaczewski · A. Pastore
Within a simple SO(8) algebraic model, the coexistence between isoscalar and isovector pairing modes can be successfully described using a mean-field method plus restoration of broken symmetries. In order to port this methodology to real nuclei, we need to employ realistic density functionals in the pairing channel. In this article, we present an analytical derivation of matrix elements of a separable pairing interaction in Cartesian coordinates and we correct errors of derivations available in the literature. After implementing this interaction in the code hfodd, we study evolution of pairing gaps in the chain of deformed Erbium isotopes, and we compare the results with a standard density-dependent contact pairing interaction.
Comments:
Contribution to the proceedings of the 27th International Nuclear Physics Conference (INPC), 29th July - 2nd August (2019), Glasgow, United Kingdom
Subjects:
Nuclear Theory (nucl-th)
arXiv:
1909.13041 [pdf]
J.Phys.Conf.Ser.(2020)·2 citations
04
[Submitted on 30 Sept 2019]
Robust ab initio predictions for nuclear rotational structure in the Be isotopes
M. A. Caprio · P. J. Fasano · J. P. Vary · P. Maris · J. Hartley
No-core configuration interaction (NCCI) calculations for p-shell nuclei give rise to rotational bands, identified by strong intraband E2 transitions and by rotational patterns for excitation energies, electromagnetic moments, and electromagnetic transitions. However, convergence rates differ significantly for different rotational observables and for different rotational bands. The choice of internucleon interaction may also substantially impact the convergence rates. Consequently, there is a substantial gap between simply observing the qualitative emergence of rotation in ab initio calculations and actually carrying out detailed quantitative comparisons. In this contribution, we illustrate the convergence properties of rotational band energy parameters extracted from NCCI calculations, and compare these predictions with experiment, for the isotopes 7-11Be, and for the JISP16 and Daejeon16 interactions.
Comments:
14 pages, 6 figures; presented at the International Conference on Nuclear Theory in the Supercomputing Era, Daejeon, Republic of Korea, November 2018
Subjects:
Nuclear Theory (nucl-th)
arXiv:
1909.13417 [pdf]
Proceedings of the International Conferen…·2 citations
05
[Submitted on 30 Sept 2019]
To reach neutron-rich heavy and superheavy nuclei by multinucleon transfer reactions with radioactive isotopes
Peng-Hui Chen🇨🇳 · Fei Niu🇨🇳 · Wei Zuo🇨🇳 · Zhao-Qing Feng🇨🇳
The dynamical mechanism of multinucleon transfer (MNT) reactions has been investigated within the dinuclear system (DNS) model, in which the sequential nucleon transfer is described by solving a set of microscopically derived master equations. Production cross sections, total kinetic energy spectra, angular distribution of formed fragments in the reactions of $^{124, 132}$ Sn+ $^{238}$ U/ $^{248}$ Cm near Coulomb barrier energies are thoroughly analyzed. It is found that the total kinetic energies of primary fragments are dissipated from the relative motion energy and rotational energy of the two colliding nuclei. The fragments are formed in the forward angle domain. The energy dependence of the angular spectra is different between projectile-like and target-like fragments. Isospin equilibrium is governed under the potential energy surface. The production cross sections of neutron-rich isotopes are enhanced around the shell closure.
Comments:
10 pages, 8 figures, 1 table
Subjects:
Nuclear Theory (nucl-th)
arXiv:
1909.13431 [pdf]
PRC(2020)·22 citations
06
[Submitted on 30 Sept 2019]
Effects of curvature of the symmetry energy in Sn+Sn reactions at 270 MeV/nucleon
Ya-Fei Guo · Gao-Chan Yong
Based on the Isospin-dependent Boltzmann-Uehling-Uhlenbeck (IBUU) transport model, the isotope Sn+Sn reactions at 270 MeV/nucleon are investigated. It is shown that nucleon and meson observables in the Sn+Sn reactions at 270 MeV/nucleon cannot effectively probe the high-density symmetry energy. These observables, however, are sensitive to the curvature of the symmetry energy. It thus sheds light on the study of the high-density behavior of the nuclear symmetry energy by extracting the curvature of the symmetry energy through the interpretation of forthcoming RIBF/RIKEN related data.
Comments:
5 pages, 8 figures
Subjects:
Nuclear Theory (nucl-th); Nuclear Experiment (nucl-ex)
arXiv:
1909.13566 [pdf]
2 citations
07
[Submitted on 30 Sept 2019]
Transition densities and form factors in the triangular $α$ -cluster model of $^{12}$ C with application to $^{12}$ C+ $α$ scattering
A. Vitturi · J. Casal · L. Fortunato · E.G. Lanza
Densities and transition densities are computed in an equilateral triangular alpha-cluster model for $^{12}$ C, in which each $α$ particle is taken as a gaussian density distribution. The ground-state, the symmetric vibration (Hoyle state) and the asymmetric bend vibration are analyzed in a molecular approach and dissected into their components in a series of harmonic functions, revealing their intrinsic structures. The transition densities in the laboratory frame are then used to construct form-factors and to compute DWBA inelastic cross-sections for the $^{12}$ C $(α, α^{'})$ reaction. The comparison with experimental data indicates that the simple geometrical model with rotations and vibrations gives a reliable description of reactions where $α$ -cluster degrees of freedom are involved.
Subjects:
Nuclear Theory (nucl-th)
arXiv:
1909.13571 [pdf]
PRC(2020)·13 citations
08
[Submitted on 27 Sept 2019]
Combining nuclear reactions and structure with the dispersive optical model
W. H. Dickhoff · M. C. Atkinson
A review of recent applications of the nonlocal dispersive optical model (DOM) is presented that allows a simultaneous description of nuclear structure and nuclear reactions. An assessment of the quality of the resulting potentials for $^{40}$ Ca and $^{48}$ Ca is discussed for the description of the $(e, e^{'} p)$ reaction to valence hole states and the possibility of interpreting the data in terms of absolute spectroscopic factors. The relevance of these results in the context of conflicting interpretations between transfer and knockout reactions is pointed out as well as the importance of proton reaction cross sections for isotopes with neutron excess. Application of the nonlocal DOM to $^{48}$ Ca incorporates the effect of the 8 additional neutrons and allows for an excellent description of elastic scattering data of both protons and neutrons. The corresponding neutron distribution constrained by all available data generates a prediction for the neutron skin that is larger than most mean-field and available \textit{ab initio} results. Results are presented for the most recent nonlocal DOM analysis of $^{208}$ Pb.
Comments:
7 pages, 3 figures, INPC2019 invited talk. arXiv admin note: substantial text overlap with arXiv:1812.07622
Subjects:
Nuclear Theory (nucl-th)
arXiv:
1909.13750 [pdf]
J.Phys.Conf.Ser.(2020)·1 citation
09
[Submitted on 30 Sept 2019]
Comment on the recent article "Fission dynamics of from saddle to scission and beyond" by Bulgac et al., published in Phys. Rev. {\bf C 100}, 034615 (2019)
Sakir Ayik🇺🇸 · Denis Lacroix🇫🇷
In this note we provide answers to criticisms made the appendix D of the article [Phys. Rev. C100, 034615 (2019)] against to the theory developed recently and known a "Stochastic Mean-Field" (SMF) approach and its applications. Briefly, we list our replies and leave the judgment to the readers.
Comments:
3 pages, no figures
Subjects:
Nuclear Theory (nucl-th)
arXiv:
1909.13761 [pdf]
1 citation
10
[Submitted on 30 Sept 2019]
Long-range azimuthal correlations for partially coherent pion emission in proton-proton collisions
Peng Ru🇨🇳 · Wei-Ning Zhang🇨🇳
In this paper, we investigate the influence of coherent pion emission on long-range azimuthal correlations in relativistic proton-proton collisions. We study the pion momentum distribution for a coherent source with both transverse and Bjorken longitudinal expansions, and calculate the two-particle correlation function $C (Δ η, Δ ϕ)$ . A "ridge" structure is observed in the correlation function $C (Δ η, Δ ϕ)$ of the coherent pion emission, whether the coherent source is expanding or static. The onset of this long-range azimuthal correlation can be traced back to the asymmetric initial transverse profile of the coherent source, owing to the interference in coherent emission. We further construct a partially coherent pion-emitting source by incorporating a chaotic emission component. From the experimental data of the two-pion Hanbury-Brown-Twiss correlations in pp collisions at $s = 7$ TeV, we extract a coherent fraction of pion emission, which increases with increasing charged-particle multiplicity, as an input of the partially coherent source model. The ridge structure is observed in the correlation function $C (Δ η, Δ ϕ)$ for the partially coherent source. The correlation becomes stronger at higher multiplicities because of the larger degrees of coherence. The results in this work are meaningful for fully understanding the collectivity in the small system of pp collisions.
Comments:
9 pages, 8 figures
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph)
arXiv:
1909.13785 [pdf]
PLB(2020)·1 citation
11
[Submitted on 30 Sept 2019]
Form factors for the Nucleon-to-Roper electromagnetic transition at large- $Q^{2}$
José Rodríguez-Quintero🇪🇸 · Daniele Binosi🇮🇹 · Chen Chen🇩🇪 · Ya Lu🇨🇳 · Craig D. Roberts🇨🇳 · Jorge Segovia🇪🇸
We report on a recent calculation of all Roper-related electromagnetic transtions form factors, covering the range of energies that next-to-come planned experiments are expected to map. Direct reliable calculations were performed, within a Poincaré covariant approach of the three-body bound-state problem, up to $Q^{2} / m_{N}^{2}$ =6; approximated then by applying the Schlessinger point method and the results eventually extended up to $Q^{2} / m_{N}^{2} ≃$ 12 via analytic continuation.
Comments:
NStar 2019 proceedings
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph); Nuclear Experiment (nucl-ex)
arXiv:
1909.13793 [pdf]
EPJ Web Conf.(2020)·8 citations
12
[Submitted on 27 Sept 2019] (cross-list from hep-ph)
Radiative quark $p_{⊥}$ -broadening in a quark-gluon plasma at RHIC and LHC energies
B.G. Zakharov🇷🇺
We study the radiative correction to $p_{⊥}$ -broadening of a fast quark in a quark-gluon plasma beyond the soft gluon approximation. We find that the radiative contribution to quark $⟨ p_{⊥}^{2} ⟩$ for RHIC and LHC conditions is negative.
Comments:
4 pages, 1 figure, proceedings for QCD Moriond 2019
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
1909.12871 [pdf]
0 citations
13
[Submitted on 29 Sept 2019] (cross-list from hep-ph)
A new description of transverse momentum spectra of identified particles produced in proton-proton collisions at high energies
Pei-Pin Yang🇨🇳 · Fu-Hu Liu🇨🇳 · Raghunath Sahoo🇮🇳
The transverse momentum spectra of identified particles produced in high energy proton-proton ( $p + p$ ) collisions are empirically described by a new method with the framework of participant quark model or the multisource model at the quark level, in which the source itself is exactly the participant quark. Each participant (constituent) quark contributes to the transverse momentum spectrum, which is described by the TP-like function, a revised Tsallis--Pareto-type function. The transverse momentum spectrum of the hadron is the convolution of two or more TP-like functions. For a lepton, the transverse momentum spectrum is the convolution of two TP-like functions due to two participant quarks, e.g. projectile and target quarks, taking part in the collisions. A discussed theoretical approach seems to describe the $p + p$ collisions data at center-of-mass energy $s = 200$ GeV, 2.76 TeV, and 13 TeV very well.
Comments:
19 pages, 7 figures. Advances in High Energy Physics, accepted
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Experiment (hep-ex); Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
arXiv:
1909.13235 [pdf]
Adv.High Energy Phys.(2020)·12 citations
14
[Submitted on 30 Sept 2019] (cross-list from hep-ph)
Glauber model for small system using anisotropic and inhomogeneous density profile of proton
Suman Deb🇮🇳 · Golam Sarwar🇮🇳 · Dhananjaya Thakur🇮🇳 · Pavish S.🇮🇳 · Raghunath Sahoo🇮🇳 · Jan-e Alam🇮🇳
Recent studies reveal that at high energies, collisions of small system like $p + p$ gives signatures similar to that widely observed in heavy ion collisions hinting towards a possibility of forming a medium with collective behaviour. With this motivation, we have used the Glauber model, which is traditionally applied to heavy ion collisions, in small system using anisotropic and inhomogeneous density profile of proton and found that the proposed model reproduces the charged particle multiplicity distribution of $p + p$ collisions at LHC energies very well. Collision geometric properties like mean impact parameter, mean number of binary collisions ( $⟨ N_{co l l} ⟩$ ) and mean number of participants ( $⟨ N_{p a r t} ⟩$ ) at different multiplicities are determined. Having estimated $⟨ N_{co l l} ⟩$ , we have calculated nuclear modification-like factor ( $R_{H L}$ ) in $p + p$ collisions. We also estimated eccentricity and elliptic flow as a function of charged particle multiplicity using the linear response to initial geometry.
Comments:
Same as published version
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
arXiv:
1909.13509 [pdf]
PRD(2020)·10 citations
15
[Submitted on 30 Sept 2019] (cross-list from hep-lat)
Long-distance Contributions to Neutrinoless Double Beta Decay $π^{-} \to π^{+} ee$
Xin-Yu Tuo🇨🇳 · Xu Feng🇨🇳 · Lu-Chang Jin🇺🇸
Neutrinoless double beta decay, if detected, would prove that neutrinos are Majorana fermions and provide the direct evidence for lepton number violation. If such decay would exist in nature, then $π^{-} π^{-} \to ee$ and $π^{-} \to π^{+} ee$ (or equivalently $π^{-} e^{+} \to π^{+} e^{-}$ ) are the two simplest processes accessible via first-principle lattice QCD calculations. In this work, we calculate the long-distance contributions to the $π^{-} \to π^{+} ee$ transition amplitude using four ensembles at the physical pion mass with various volumes and lattice spacings. We adopt the infinite-volume reconstruction method to control the finite-volume effects arising from the (almost) massless neutrino. Providing the lattice QCD inputs for chiral perturbation theory, we obtain the low energy constant $g_{ν}^{π π} (m_{ρ}) = - 10.89 (28)_{stat} (74)_{sys}$ , which is close to $g_{ν}^{π π} (m_{ρ}) = - 11.96 (31)_{stat}$ determined from the crossed-channel $π^{-} π^{-} \to ee$ decay.
Comments:
19 pages, 6 figures
Subjects:
High Energy Physics — Lattice (hep-lat); High Energy Physics — Phenomenology (hep-ph); Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
arXiv:
1909.13525 [pdf]
PRD(2019)·56 citations
16
[Submitted on 27 Sept 2019] (cross-list from hep-ph)
The proton structure via double parton scattering
Matteo Rinaldi🇮🇹
In this talk we present the results of the investigation on the so called double parton distribution functions (dPDFs), accessible quantities in high energy proton-proton and proton nucleus collisions, in double parton scattering processes (DPS). These new and almost unknown distributions encode information on how partons inside a proton are correlated among each other and represent a new tool to explore the three dimensional partonic structure of hadrons. In the present contribution, results of the calculations of dPFDs are presented also including phenomenological investigations on the impact of double correlations in experimental observables, showing how the latter could be observed in the next LHC run. In addition we discuss how present information on experimental observables could be related to the transverse proton structure.
Comments:
6 pages, 3 figures, contribution to the proceedings of the 27th International Nuclear Physics Conference (INPC) 2019, July 29- August 2, Glasgow, UK. arXiv admin note: text overlap with arXiv:1703.10905
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
1909.13748 [pdf]
J.Phys.Conf.Ser.(2020)·1 citation
17
[Submitted on 30 Sept 2019] (cross-list from hep-ph)
Process-independent effective coupling and the pion structure function
José Rodríguez-Quintero🇪🇸 · Lei Chang🇨🇳 · Khépani Raya🇨🇳 · Craig D. Roberts🇨🇳
We sketch the calculation of the pion structure functions within the DSE framework, following two alternative albeit consistent approaches, and discuss then their QCD evolution, the running driven by an effective charge, from a hadronic scale up to any larger one accessible to experiment.
Comments:
INPC 2019 proceedings
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
arXiv:
1909.13802 [pdf]
J.Phys.Conf.Ser.(2020)·9 citations
18
[Submitted on 30 Sept 2019] (cross-list from hep-ph)
Unified Description of Polarized and Unpolarized Quark Distributions in the Proton
Tianbo Liu🇺🇸 · Raza Sabbir Sufian🇺🇸 · Guy F. de Téramond🇨🇷 · Hans Günter Dosch🇩🇪 · Stanley J. Brodsky🇺🇸 · Alexandre Deur🇺🇸
We propose a unified new approach to describe polarized and unpolarized quark distributions in the proton based on the gauge-gravity correspondence, light-front holography, and the generalized Veneziano model. We find that the spin-dependent quark distributions are uniquely determined in terms of the unpolarized distributions by chirality separation without the introduction of additional free parameters. The predictions are consistent with existing experimental data and agree with perturbative QCD constraints at large longitudinal momentum $x$ . In particular, we predict the sign reversal of the polarized down-quark distribution in the proton at $x = 0.8 \pm 0.03$ , a key property of nucleon substructure which will be tested very soon in upcoming experiments.
Comments:
7 pages, 3 figures, version to appear in Physical Review Letters
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Experiment (hep-ex); Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
arXiv:
1909.13818 [pdf]
PRL(2020)·43 citations
19
[Submitted on 30 Sept 2019] (cross-list from hep-ph)
Quark model calculations of transition form factors at high photon virtualities
G. Ramalho🇧🇷
We present calculations of $γ^{*} N \to N^{*}$ transition form factors, where $N$ is the nucleon and $N^{*}$ is a nucleon resonance, based on a covariant quark model. Our main focus is at high photon virtualities (large $Q^{2}$ ) where the valence quark degrees of freedom dominate the contributions to the transition form factors and helicity amplitudes. In that regime, the quark model estimates can be compared with the available data, particularly with the Jefferson Lab data at intermediate and large momentum transfer ( $Q^{2} > 2$ GeV $^{2}$ ). The main focus is on the $Δ (1232) 3/ 2^{+}$ , $N (1440) 1/ 2^{+}$ , $N (1535) 1/ 2^{-}$ and $N (1520) 3/ 2^{-}$ resonances, but estimates for other higher mass resonances are also discussed.
Comments:
Published version. 9 pages, 9 figures
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Experiment (hep-ex); High Energy Physics — Lattice (hep-lat); Nuclear Theory (nucl-th)
arXiv:
1909.13825 [pdf]
EPJ Web Conf.(2020)·1 citation

Affiliations

first authorsco-authorsvia INSPIRE