Nuclear Theory·nucl-th

Monday·May 7, 2018

5 papers—3 primary·2 cross-listed

01
[Submitted on 4 May 2018]
Parametrization of cross sections for elementary hadronic collisions involving strange particles
J. Hirtz🇫🇷 · J.-C. David🇫🇷 · A. Boudard🇫🇷 · J. Cugnon🇧🇪 · S. Leray🇫🇷 · I. Leya🇨🇭 · D. Mancusi🇫🇷
The production of strange particles (kaons, hyperons) and hypernuclei in light charged particle induced reactions in the energy range of a few GeV (2-15 GeV) has become a topic of active research in several facilities (e.g., HypHI and PANDA at GSI and/or FAIR (Germany), JLab (USA), and JPARC (Japan)). This energy range represents the low-energy limit of the string models (degree of freedom: quark and gluon) or the high-energy limit of the so-called spallation models (degree of freedom: hadrons). A well known spallation model is INCL, the Liège intranuclear cascade model (combined with a de-excitation model to complete the reaction). INCL, known to give good results up to 2-3 GeV, was recently upgraded by the implementation of multiple pion emission to extend the energy range of applicability up to roughly 15 GeV. The next step, to account also for strange particle production, both for refining the high energy domain and making it usable when strangeness appears, requires the following main ingredients: i) the relevant elementary cross sections (production, scattering, and absorption) and ii) the characteristics of the associated final states. Some of those ingredients are already known and, sometimes, are already used in models of the same type (e.g., Bertini, GiBUU), but this paper aims at reviewing the situation by compiling, updating, and comparing the necessary elementary information which are independent of the model used.
Subjects:
Nuclear Theory (nucl-th)
arXiv:
1805.01655 [pdf]
Eur.Phys.J.Plus(2018)·19 citations
02
[Submitted on 4 May 2018]
Spectral function for $D ˉ_{0}^{*}$ $(0^{+})$ meson in isospin asymmetric nuclear matter with chiral partner structure
Daiki Suenaga🇯🇵
We study a spectral function for $D ˉ_{0}^{*}$ $(0^{+})$ meson in symmetric and neutron-rich asymmetric nuclear matter from the viewpoint of the partial restoration of chiral symmetry. Nuclear matter is constructed by a parity doublet model with hidden local symmetry which can reproduce properties at normal nuclear matter density as well as those in the vacuum. $D ˉ$ mesons are introduced by the chiral partner structure. Our results show that a mass of $D ˉ$ ( $0^{-}$ ) meson increases while a mass of $D ˉ_{0}^{*}$ meson decreases at mean field level as we increase the baryon density, reflecting the partial restoration of chiral symmetry. In the spectral function for $D ˉ_{0}^{*}$ meson, we find a threshold enhancement is remarkably enhanced which indicates this peak is an appropriate probe to observe the partial restoration of chiral symmetry in nuclear matter. We also find a resonance of $D ˉ_{0}^{*}$ meson revives at higher density due to a narrowing of the phase space. In the spectral function in neutron-rich asymmetric nuclear matter, we observe the threshold enhancement in negatively-charged $D ˉ_{0}^{*}$ meson channel stands at higher energy and its height is more enhanced compared to neutral $D ˉ_{0}^{*}$ meson channel, due to the violation of isospin symmetry. On the other hand, the resonance of negatively-charged $D ˉ_{0}^{*}$ meson is slightly suppressed compared to the neutral one.
Comments:
17 pages, 8 figures
Subjects:
Nuclear Theory (nucl-th)
arXiv:
1805.01709 [pdf]
6 citations
03
[Submitted on 4 May 2018]
Hindered alpha decays of heaviest high-K isomers
P. Jachimowicz · M. Kowal · J. Skalski
To find candidates for long-lived high-K isomers in even-even Z=106-112 superheavy nuclei we study dominant alpha-decay channel of two- and four-quasi-particle configurations at a low excitation. Energies are calculated within the microscopic - macroscopic approach with the deformed Woods-Saxon potential. Configurations are fixed by a standard blocking procedure and their energy found by a subsequent minimization over deformations. Different excitation energies of a high-K configuration in parent and daughter nucleus seem particularly important for a hindrance of the alpha-decay. A strong hindrance is found for some four-quasi-particle states, particularly $K^{π} = 2 0^{+}$ and/or $1 9^{+}$ states in $^{264 - 270}$ Ds. Contrary to what was suggested in experimental papers, it is rather a proton configuration that leads to this strong hindrance. If not shortened by the electromagnetic decay, alpha half-lives of $\sim$ 1 s could open new possibilities for studies of chemical/atomic properties of related elements.
Subjects:
Nuclear Theory (nucl-th)
arXiv:
1805.01732 [pdf]
PRC(2018)·11 citations
04
[Submitted on 3 May 2018] (cross-list from hep-ph)
Pion-pole contribution to hadronic light-by-light scattering in the anomalous magnetic moment of the muon
Martin Hoferichter🇺🇸 · Bai-Long Hoid🇩🇪 · Bastian Kubis🇩🇪 · Stefan Leupold🇸🇪 · Sebastian P. Schneider🇩🇪
The $π^{0}$ pole constitutes the lowest-lying singularity of the hadronic light-by-light (HLbL) tensor, and thus provides the leading contribution in a dispersive approach to HLbL scattering in the anomalous magnetic moment of the muon $(g - 2)_{μ}$ . It is unambiguously defined in terms of the doubly-virtual pion transition form factor, which in principle can be accessed in its entirety by experiment. We demonstrate that, in the absence of a direct measurement, the full space-like doubly-virtual form factor can be reconstructed very accurately based on existing data for $e^{+} e^{-} \to 3 π$ , $e^{+} e^{-} \to e^{+} e^{-} π^{0}$ , and the $π^{0} \to γ γ$ decay width. We derive a representation that incorporates all the low-lying singularities of the form factor, matches correctly onto the asymptotic behavior expected from perturbative QCD, and is suitable for the evaluation of the $(g - 2)_{μ}$ loop integral. The resulting value, $a_{μ}^{π^{0} -pole} = 62. 6_{- 2.5}^{+ 3.0} \times 1 0^{- 11}$ , for the first time, represents a complete data-driven determination of the pion-pole contribution with fully controlled uncertainty estimates. In particular, we show that already improved singly-virtual measurements alone would allow one to further reduce the uncertainty in $a_{μ}^{π^{0} -pole}$ .
Comments:
7 pages, 4 figures; journal version
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Experiment (hep-ex); High Energy Physics — Lattice (hep-lat); Nuclear Theory (nucl-th)
arXiv:
1805.01471 [pdf]
PRL(2018)·200 citations
05
[Submitted on 4 May 2018] (cross-list from hep-ph)
Matching the Nonequilibrium Initial Stage of Heavy Ion Collisions to Hydrodynamics with QCD Kinetic Theory
Aleksi Kurkela🇨🇭 · Aleksas Mazeliauskas🇩🇪 · Jean-François Paquet🇺🇸 · Sören Schlichting🇺🇸 · Derek Teaney🇺🇸
High-energy nuclear collisions produce a nonequilibrium plasma of quarks and gluons which thermalizes and exhibits hydrodynamic flow. There are currently no practical frameworks to connect the early particle production in classical field simulations to the subsequent hydrodynamic evolution. We build such a framework using nonequilibrium Green's functions, calculated in QCD kinetic theory, to propagate the initial energy-momentum tensor to the hydrodynamic phase. We demonstrate that this approach can be easily incorporated into existing hydrodynamic simulations, leading to stronger constraints on the energy density at early times and the transport properties of the QCD medium. Based on (conformal) scaling properties of the Green's functions, we further obtain pragmatic bounds for the applicability of hydrodynamics in nuclear collisions.
Comments:
7 pages, 4 figures, v2: typos corrected and minor changes, version accepted for publication in Phys. Rev. Lett., see also our companion paper arXiv:1805.00961 for the extensive details, for the code of linear kinetic theory propagator KoMPoST used for this study see https://github.com/KMPST/KoMPoST ; v3 updated references, published version
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
1805.01604 [pdf]
PRL(2019)·252 citations

Affiliations

first authorsco-authorsvia INSPIRE

Parametrization of cross sections for elementary hadronic collisions involving strange particles

Spectral function for Dˉ0∗​ (0+) meson in isospin asymmetric nuclear matter with chiral partner structure

Hindered alpha decays of heaviest high-K isomers

Pion-pole contribution to hadronic light-by-light scattering in the anomalous magnetic moment of the muon

Matching the Nonequilibrium Initial Stage of Heavy Ion Collisions to Hydrodynamics with QCD Kinetic Theory

Affiliations

Spectral function for $D ˉ_{0}^{*}$ $(0^{+})$ meson in isospin asymmetric nuclear matter with chiral partner structure