Nuclear Theory·nucl-th

Wednesday·August 10, 2016

6 papers—5 primary·1 cross-listed

01
The electromagnetic form factors of the $Λ$ in the timelike region
J. Haidenbauer🇩🇪 · U.-G. Meißner🇩🇪
The reaction $e^{+} e^{-} \to Λ ˉ Λ$ is investigated for energies close to the threshold. Specific emphasis is put on the role played by the interaction in the final $Λ ˉ Λ$ system which is taken into account rigorously. For that interaction a variety of $Λ ˉ Λ$ potential models is employed that have been constructed for the analysis of the reaction $p ˉ p \to Λ ˉ Λ$ in the past. The enhancement of the effective form factor for energies close to the $Λ ˉ Λ$ threshold, seen in pertinent experiments, is reproduced. Predictions for the $Λ$ electromagnetic form factors $G_{M}$ and $G_{E}$ in the timelike region and for spin-dependent observables such as spin-correlation parameters are presented.
nucl-thPLB(2016)·65 citations
02
Effective field theory for vibrations in odd-mass nuclei
E. A. Coello Pérez · T. Papenbrock
Heavy even-even nuclei exhibit low-energy collective excitations that are separated in scale from the microscopic (fermion) degrees of freedom. This separation of scale allows us to approach nuclear vibrations within an effective field theory (EFT). In odd-mass nuclei collective and single-particle properties compete at low energies, and this makes their description more challenging. In this article we describe odd-mass nuclei with ground-state spin $I = \sfrac 12$ by means of an EFT that couples a fermion to the collective degrees of freedom of an even-even core. The EFT relates observables such as energy levels, electric quadrupole ( $E 2$ ) transition strengths, and magnetic dipole ( $M 1$ ) moments of the odd-mass nucleus to those of its even-even neighbor, and allows us to quantify theoretical uncertainties. For isotopes of rhodium and silver the theoretical description is consistent with data within experimental and theoretical uncertainties. Several testable predictions are made.
nucl-thPRC(2016)·18 citations
03
Light cluster production at NICA
N.-U. Bastian🇵🇱 · P. Batyuk🇷🇺 · D. Blaschke🇷🇺 · P. Danielewicz🇺🇸 · Yu. B. Ivanov🇷🇺 · Iu. Karpenko🇺🇦 · G. Röpke🇷🇺 · O. Rogachevsky🇷🇺 · H. H. Wolter🇩🇪
Light cluster production at the NICA accelerator complex offers unique possibilities to use these states as "rare probes" of in-medium characteristics such as phase space occupation and early flow. In order to explain this statement, in this contribution theoretical considerations from the nuclear statistical equilibrium model and from a quantum statistical model of cluster production are supplemented with a discussion of a transport model for light cluster formation and with results from hydrodynamic simulations combined with the coalescence model.
nucl-thnucl-exEPJA(2016)·22 citations
04
The neutron within the deuteron as a surrogate for neutron-induced reactions
C. A. Bertulani · L. F. Canto · M. S. Hussein · Shubhchintak · Viet Nhan Hao Tran
We propose the use of neutron poisons in reactions induced by radioactive beams as a test of theoretical models aiming to relate neutron capture in nuclei with neutron surrogate reactions such as (d,p) reactions. We exploit the approximations necessary to obtain a direct relation between the two reactions; surrogate vs. neutron capture. We also show how this is intimately related to the momentum distribution of the neutron within the deuteron. The models we use are based on the theory of inclusive breakup reactions commonly employed in the treatment of incomplete fusion and surrogate method. Such theories were developed in the 80's by Ichimura, Autern and Vincent [Phys. Rev. C 32, 431 (1985)], Udagawa and Tamura [Phys. Rev. C 24, 1348 (1981)] and Hussein and McVoy [Nucl. Phys. A 445, 124 (1985)]. We use these theories to derive an expression for the proton yield in the reaction A(d,p)B. The capture reaction $n + A \to B$ is then extracted using reasonable approximations. By recalling an old method proposed by Serber [Phys. Rev. 80, 1098 (1950); Nature 166, 709 (1950)] we explain how the momentum distribution of neutrons within the deuteron will depend on the short-range dependence of the nucleon-nucleon force. The relevance of our work to nucleosynthesis in the rapid neutron capture process is emphasized.
nucl-thIJMPE(2020)·4 citations
05
Selection rules for ^48Cr
Michael Quinonez · Arun Kingan · Xiaofei Yu · L. Zamick
In the single j shell(f_{7/2}){}^{48} Cr is the first even-even nucleus for which there are T=0 (Isoscalar) J=1^{+} states and T=1J=0^{+}These states are here studied. This nucleus ,in the same model space, is mid-shell for both neutrons and protons and this leads to many selection rules.
nucl-thRom.J.Phys.(2018)·2 citations
06
Spectra and rates of bremsstrahlung neutrino emission in stars
Gang Guo🇨🇳 · Yong-Zhong Qian🇺🇸
We calculate the energy-differential rate for neutrino emission from electron-nucleus bremsstrahlung in stellar interiors taking into account the effects of electron screening and ionic correlations. We compare the energy-differential and the net rates, as well as the average $ν ˉ_{e}$ and $ν ˉ_{x}$ $(x = μ, τ)$ energies, for this process with those for $e^{\pm}$ pair annihilation, plasmon decay, and photo-neutrino emission over a wide range of temperature and density. We also compare our updated energy loss rates for the above thermal neutrino emission processes with the fitting formulas widely used in stellar evolution models and determine the temperature and density domain in which each process dominates. We discuss the implications of our results for detection of $ν ˉ_{e}$ from massive stars during their pre-supernova evolution and find that pair annihilation makes the predominant contribution to the signal from the thermal emission processes.
↳ astro-ph.SRhep-phnucl-thPRD(2016)·16 citations

Affiliations

first authorsco-authorsvia INSPIRE

The electromagnetic form factors of the Λ in the timelike region

Effective field theory for vibrations in odd-mass nuclei

Light cluster production at NICA

The neutron within the deuteron as a surrogate for neutron-induced reactions

Selection rules for ^48Cr

Spectra and rates of bremsstrahlung neutrino emission in stars

Affiliations

The electromagnetic form factors of the $Λ$ in the timelike region