Nuclear Theory·nucl-th

Monday·June 15, 2015

9 papers—6 primary·3 cross-listed

01
Hydrodynamic Approaches in Relativistic Heavy Ion Reactions
Rafael Derradi de Souza🇧🇷 · Tomoi Koide🇧🇷 · Takeshi Kodama🇧🇷
We review several facets of the hydrodynamic description of the relativistic heavy ion collisions, starting from the historical motivation to the present understandings of the observed collective aspects of experimental data, especially those of the most recent RHIC and LHC results. In this report, we particularly focus on the conceptual questions and the physical foundations of the validity of the hydrodynamic approach itself. We also discuss recent efforts to clarify some of the points in this direction, such as the various forms of derivations of relativistic hydrodynamics together with the limitations intrinsic to the traditional approaches, variational approaches, known analytic solutions for special cases, and several new theoretical developments. Throughout this review, we stress the role of course-graining procedure in the hydrodynamic description and discuss its relation to the physical observables through the analysis of a hydrodynamic mapping of a microscopic transport model. Several questions to be answered to clarify the physics of collective phenomena in the relativistic heavy ion collisions are pointed out.
nucl-thhep-phPPNP(2016)·206 citations
02
Towards experimental search for the atomic effect in alpha decay: comparison of the adiabatic approach with the frozen shell model
Feodor F. Karpeshin · Malvina B. Trzhaskovskaya
We study the important for the experiment features of the effect of the electron shell on alpha decay in the adiabatic approach. The effect is of tenths of a percent or less in magnitude, depending on the transition energy and the atomic number. On the other hand, we show the predominant role of the inner shells: more than 80% of the effect are due to the 1s electrons. This fact is crucial for the experiment, allowing one to perform measurements in the same storage rings, comparing for example, the probability of decay in the bare nuclei and Helium-like ions. The analysis is presented concerning the reasons for the relative success and the limits of applicability of the model of "frozen" electron shell used to calculate the effect for more than half a century.
nucl-th0 citations
03
New insights on the hyperon puzzle from quantum Monte Carlo calculations
Francesco Pederiva🇮🇹 · Francesco Catalano🇸🇪 · Diego Lonardoni🇮🇹 · Alessandro Lovato🇺🇸 · Stefano Gandolfi🇺🇸
In the last years auxiliary field diffusion Monte Carlo has been used to assess the properties of hypernuclear systems, from light- to medium-heavy hypernuclei and hyper-neutron matter. One of the main findings is the key role played by the three-body hyperon-nucleon-nucleon interaction in the determination of the hyperon separation energy of hypernuclei and as a possible solution to the hyperon puzzle. However, there are still aspects of the employed hypernuclear potential that remain to be carefully investigated. In this paper we show that the isospin dependence of the Lambda-NN force, which is crucial in determining the NS structure, is poorly constrained by the available experimental data.
nucl-th6 citations
04
A Study of Shell Model Neutron States in $^{207, 209} P b$ Using the Generalized Woods-Saxon plus Spin-Orbit Potential
J. A. Liendo🇻🇪 · E. Castro🇻🇪 · R. Gómez🇻🇪 · D. D. Caussyn🇺🇸
The experimental binding energies of single-particle and single-hole neutron states belonging to neutron shells that extend from N = 126 to 184 and 82 to 126 respectively, have been reproduced by solving the Schrödinger equation with a potential that has two components: the generalized Woods-Saxon (GWS) potential and the spin-orbit (SO) coupling term. The GWS potential contains the traditional WS potential plus a term (SU) whose intensity reaches a maximum in the nuclear surface. Our results indicate the existence of a explicit relationship between the strength of the SU potential and the orbital angular momentum quantum number $ℓ$ of the state. This dependence has been used to make reasonable predictions for the excitation energy centroids of states located inside and outside the neutron shells investigated. Comparisons are made with results reported in previous investigations.
nucl-thIJMPE(2016)·6 citations
05
Lepton polarization asymmetries for FCNC decays of the $Λ_{b}$ baryon
L. Mott🇺🇸 · W. Roberts🇺🇸
Branching ratios, lepton forward-backward asymmetries, and lepton polarization asymmetries for the flavor-changing neutral current (FCNC) dileptonic decays of the $Λ_{b}$ baryon to the ground state and a number of excited state $Λ$ baryons are calculated using form factors extracted using wave functions from a constituent quark model. The SM branching ratios for the transition to the ground state calculated using these quark model form factors are consistent with the recent measurement reported by the LHCb collaboration. It is shown that the lepton polarization asymmetries are largely insensitive to the transition form factors and, therefore, to the effects of QCD in the nonperturbative regime. These observables can therefore provide somewhat model independent ways of extracting various combinations of the Wilson coefficients.
nucl-thhep-exhep-phInt.J.Mod.Phys.A(2015)·19 citations
06
Laser-Nucleus Interactions: The Quasiadiabatic Regime
Adriana Pálffy · Oliver Buss · Axel Hoefer · Hans A. Weidenmüller
The interaction between nuclei and a strong zeptosecond laser pulse with coherent MeV photons is investigated theoretically. We provide a first semi-quantitative study of the quasiadiabatic regime where the photon absorption rate is comparable to the nuclear equilibration rate. In that regime, multiple photon absorption leads to the formation of a compound nucleus in the so-far unexplored regime of excitation energies several hundred MeV above the yrast line. The temporal dynamics of the process is investigated by means of a set of master equations that account for dipole absorption, stimulated dipole emission, neutron decay and induced fission in a chain of nuclei. That set is solved numerically by means of state-of-the-art matrix exponential methods also used in nuclear fuel burnup and radioactivity transport calculations. Our quantitative estimates predict the excitation path and range of nuclei reached by neutron decay and provide relevant information for the layout of future experiments.
nucl-thnucl-exPRC(2015)·16 citations
07
Nuclear fusion in the deuterated cores of inflated hot Jupiters
Rachid Ouyed (1) · Prashanth Jaikumar (2) ((1) Department of Physics and Astronomy, University of Calgary, Canada, (2) Department of Physics and Astronomy, California State University Long Beach, CA, USA)
Ouyed et al. (1998) proposed Deuterium (DD) fusion at the core-mantle interface of giant planets as a mechanism to explain their observed heat excess. But rather high interior temperatures (~10^5 K) and a stratified D layer are needed, making such a scenario unlikely. In this paper, we re-examine DD fusion, with the addition of screening effects pertinent to a deuterated core containing ice and some heavy elements. This alleviates the extreme temperature constraint and removes the requirement of a stratified D layer. As an application, we propose that, if their core temperatures are a few times 10^4 K and core composition is chemically inhomogeneous, the observed inflated size of some giant exoplanets ("hot Jupiters") may be linked to screened DD fusion occurring deep in the interior. Application of an analytic evolution model suggests that the amount of inflation from this effect can be important if there is sufficient rock-ice in the core, making DD fusion an effective extra internal energy source for radius inflation. The mechanism of screened DD fusion, operating in the above temperature range, is generally consistent with the trend in radius anomaly with planetary equilibrium temperature $T_{eq}$ , and also depends on planetary mass. Although we do not consider the effect of incident stellar flux, we expect that a minimum level of irradiation is necessary to trigger core erosion and subsequent DD fusion inside the planet. Since DD fusion is quite sensitive to the screening potential inferred from laboratory experiments, observations of inflated hot Jupiters may help constrain screening effects in the cores of giant planets.
↳ astro-ph.EPnucl-thAstrophys.Space Sci.(2016)·1 citation
08
Heavy-flavour and quarkonium production in the LHC era: from proton-proton to heavy-ion collisions
A. Andronic🇩🇪 · F. Arleo🇫🇷 · R. Arnaldi🇮🇹 · A. Beraudo🇮🇹 · E. Bruna🇮🇹 · D. Caffarri🇨🇭 · Z. Conesa del Valle🇫🇷 · J.G. Contreras🇨🇿 · T. Dahms🇩🇪 · A. Dainese🇮🇹 · M. Djordjevic🇷🇸 · E.G. Ferreiro🇪🇸 and 44 other authors
This report reviews the study of open heavy-flavour and quarkonium production in high-energy hadronic collisions, as tools to investigate fundamental aspects of Quantum Chromodynamics, from the proton and nucleus structure at high energy to deconfinement and the properties of the Quark-Gluon Plasma. Emphasis is given to the lessons learnt from LHC Run 1 results, which are reviewed in a global picture with the results from SPS and RHIC at lower energies, as well as to the questions to be addressed in the future. The report covers heavy flavour and quarkonium production in proton-proton, proton-nucleus and nucleus-nucleus collisions. This includes discussion of the effects of hot and cold strongly interacting matter, quarkonium photo-production in nucleus-nucleus collisions and perspectives on the study of heavy flavour and quarkonium with upgrades of existing experiments and new experiments. The report results from the activity of the SaporeGravis network of the I3 Hadron Physics programme of the European Union 7th Framework Programme.
↳ nucl-exhep-exhep-phnucl-thEPJC(2016)·814 citations
09
Degeneracies of particle and nuclear physics uncertainties in neutrinoless double beta decay
E. Lisi (INFN, Bari)🇮🇹 · A. Rotunno (U. of Bari)🇮🇹 · F. Simkovic (Comenius U. & JINR & CTU Prague)🇸🇰
Theoretical estimates for the half life of neutrinoless double beta decay in candidate nuclei are affected by both particle and nuclear physics uncertainties, which may complicate the interpretation of decay signals or limits. We study such uncertainties and their degeneracies in the following context: three nuclei of great interest for large-scale experiments (76-Ge, 130-Te, 136-Xe), two representative particle physics mechanisms (light and heavy Majorana neutrino exchange), and a large set of nuclear matrix elements (NME), computed within the quasiparticle random phase approximation (QRPA). It turns out that the main theoretical uncertainties, associated with the effective axial coupling g_A and with the nucleon-nucleon potential, can be parametrized in terms of NME rescaling factors, up to small residuals. From this parametrization, the following QRPA features emerge: (1) the NME dependence on g_A is milder than quadratic; (2) in each of the two mechanisms, the relevant lepton number violating parameter is largely degenerate with the NME rescaling factors; and (3) the light and heavy neutrino exchange mechanisms are basically degenerate in the above three nuclei. We comment on the challenging theoretical and experimental improvements required to reduce such particle and nuclear physics uncertainties and their degeneracies.
↳ hep-phhep-exnucl-exnucl-thPRD(2015)·29 citations

Affiliations

first authorsco-authorsvia INSPIRE