Nuclear Theory·nucl-th

Friday·September 11, 2015

14 papers—6 primary·8 cross-listed

01
[Submitted on 9 Sept 2015]
Contemporary continuum QCD approaches to excited hadrons
Bruno El-Bennich🇧🇷 · Eduardo Rojas🇨🇴
Amongst the bound states produced by the strong interaction, radially excited meson and nucleon states offer an important phenomenological window into the long-range behavior of the coupling constant in Quantum Chromodynamics. We here report on some technical details related to the computation of the bound state's eigenvalue spectrum in the framework of Bethe-Salpeter and Faddeev equations.
Comments:
Proceedings of the 21st International Conference on Few-body Problems in Physics to be published in EPJ Web of Conferences
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Lattice (hep-lat); High Energy Physics — Phenomenology (hep-ph); Nuclear Experiment (nucl-ex)
arXiv:
1509.02919 [pdf]
EPJ Web Conf.(2016)·4 citations
02
[Submitted on 9 Sept 2015]
Three Lectures on Hadron Physics
Craig D. Roberts🇺🇸
These lectures explain that comparisons between experiment and theory can expose the impact of running couplings and masses on hadron observables and thereby aid materially in charting the momentum dependence of the interaction that underlies strong-interaction dynamics. The series begins with a primer on continuum QCD, which introduces some of the basic ideas necessary in order to understand the use of Schwinger functions as a nonperturbative tool in hadron physics. It continues with a discussion of confinement and dynamical symmetry breaking (DCSB) in the Standard Model, and the impact of these phenomena on our understanding of condensates, the parton structure of hadrons, and the pion electromagnetic form factor. The final lecture treats the problem of grand unification; namely, the contemporary use of Schwinger functions as a symmetry-preserving tool for the unified explanation and prediction of the properties of both mesons and baryons. It reveals that DCSB drives the formation of diquark clusters in baryons and sketches a picture of baryons as bound-states with Borromean character. Planned experiments are capable of validating the perspectives outlined in these lectures.
Comments:
53 pages, 17 figures. Summary of three lectures delivered at "Hadron Physics XIII - XIII International Workshop on Hadron Physics", 22-27 March 2015, Hotel do Bosque, Angra dos Reis - RJ, Brazil
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Lattice (hep-lat); High Energy Physics — Phenomenology (hep-ph); Nuclear Experiment (nucl-ex)
arXiv:
1509.02925 [pdf]
J.Phys.Conf.Ser.(2016)·71 citations
03
[Submitted on 10 Sept 2015]
Constraining slope parameter of symmetry energy from nuclear structure
T. Inakura · H. Nakada
Four quantities deducible from nuclear structure experiments have been claimed to correlate to the slope parameter $L$ of the symmetry energy; the neutron skin thickness, the cross section of low-energy dipole (LED) mode, dipole polarizability $α_{D}$ , and $α_{D} S_{0}$ (i.e. product of $α_{D}$ and the symmetry energy $S_{0}$ ). By the calculations in the Hartree-Fock plus random-phase approximation with various effective interactions, we compare the correlations between $L$ and these four quantities. The correlation derived from different interactions and the correlation from a class of interactions that are identical in the symmetric matter as well as in $S_{0}$ are simultaneously examined. These two types of correlations may behave differently, as exemplified in the correlation of $α_{D}$ to $L$ . It is found that the neutron skin thickness and $α_{D} S_{0}$ correlate well to $L$ , and therefore are suitable for narrowing down the value of $L$ via experiments. The LED emergence and upgrowth makes the $α_{D} S_{0}$ - $L$ correlation strong, although these correlations are disarranged when neutron halo appears in the ground state.
Comments:
8 pages, 5 figures
Subjects:
Nuclear Theory (nucl-th)
arXiv:
1509.02982 [pdf]
PRC(2015)·21 citations
04
[Submitted on 10 Sept 2015]
Variation after full projection with triaxially deformed nuclear mean field
Zao-Chun Gao🇨🇳 · Mihai Horoi🇺🇸 · Y.S. Chen🇨🇳
We implemented a variation after projection (VAP) algorithm based on a triaxially deformed Hartree-Fock-Bogoliubov vacuum state. This is the first projected mean field study that includes all the quantum numbers (except parity), i.e., spin ( $J$ ), isospin ( $T$ ) and mass number ( $A$ ). Systematic VAP calculations with $J T A$ -projection have been performed for the even-even $s d$ -shell nuclei with the USDB Hamiltonian. All the VAP ground state energies are within 500 keV above the exact shell model values. Our VAP calculations show that the spin projection has two important effects: (1) the spin projection is crucial in achieving good approximation of the full shell model calculation. (2) the intrinsic shapes of the VAP wavefunctions with spin projection are always triaxial, while the Hartree-Fock-Bogoliubov methods likely provide axial intrinsic shapes. Finally, our analysis suggests that one may not be possible to associate an intrinsic shape to an exact shell model wave function.
Comments:
5 pages,2 figures
Subjects:
Nuclear Theory (nucl-th)
arXiv:
1509.03058 [pdf]
PRC(2015)·37 citations
05
[Submitted on 10 Sept 2015]
Photoproduction of $J / ψ$ mesons in peripheral and semi-central heavy ion collisions
Mariola Kłusek-Gawenda🇵🇱 · Antoni Szczurek🇵🇱
We calculate total and differential cross sections for $J / ψ$ photoproduction in ultrarelativistic lead-lead collisions at the LHC energy $s_{N N} = 2.76$ TeV. In the present approach we use a simple model based on vector dominance picture and multiple scattering of the hadronic ( $c c ˉ$ ) state in a cold nucleus as an example. In our analysis we use both the classical mechanics and quantum (Glauber) formulae for calculating $σ_{t o t} (J / ψ P b)$ which is a building block of our model. We compare our UPC results with ALICE and CMS data. For semi-central collisions ( $b < R_{A} + R_{B}$ ) a modification of the photon flux seems necessary. We discuss different physics motivated approximations. We try to estimate the cross sections for different centrality bins and for $J / ψ$ mesons emitted in forward rapidity range ( $2.5 < y < 4$ ) corresponding to recent ALICE experimental results. Reasonable results are obtained but open questions are discussed.
Comments:
15 pages, 9 figures and 4 tables
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Experiment (hep-ex); High Energy Physics — Phenomenology (hep-ph)
arXiv:
1509.03173 [pdf]
PRC(2016)·62 citations
06
[Submitted on 10 Sept 2015]
In-medium nucleon-nucleon elastic cross sections determined from nucleon-induced reaction cross sections data
Li Ou · Xueying He
Within the framework of the improved quantum molecular dynamics model, the medium modifications on the free nucleon-nucleon elastic cross sections are investigated. By using various in-medium nucleon-nucleon elastic cross sections in the model, the nucleon-induced reactions on various targets are simulated, and the excitation functions of reaction cross sections in the energy range from 25 MeV to 1 GeV are calculated. By comparing the calculations with the experimental data, an isospin, density, and momentum-dependence medium correction factor on free nucleon-nucleon elastic cross sections is determined.
Comments:
12 pages, 5 figures
Subjects:
Nuclear Theory (nucl-th)
arXiv:
1509.03175 [pdf]
CPC(2019)·7 citations

Affiliations

first authorsco-authorsvia INSPIRE

Contemporary continuum QCD approaches to excited hadrons

Three Lectures on Hadron Physics

Constraining slope parameter of symmetry energy from nuclear structure

Variation after full projection with triaxially deformed nuclear mean field

Photoproduction of J/ψ mesons in peripheral and semi-central heavy ion collisions

In-medium nucleon-nucleon elastic cross sections determined from nucleon-induced reaction cross sections data

Affiliations

Photoproduction of $J / ψ$ mesons in peripheral and semi-central heavy ion collisions