Nuclear Theory·nucl-th

Thursday·July 21, 2016

9 papers—5 primary·4 cross-listed

01
[Submitted on 19 Jul 2016]
Theory of inclusive breakup cross section for Borromean nuclei within a four-body spectator model
Brett V. Carlson · Tobias Frederico · Mahir S. Hussein
We develop a model to treat the inclusive non-elastic break up reactions involving weakly bound three-cluster nuclei. Borromean, two-nucleon, halo nuclei are candidates of unstable three-fragments projectiles. The model is based on the theory of inclusive breakup reactions commonly employed in the treatment of incomplete fusion and surrogate method. The theory was developed in the 80's by Ichimura, Autern and Vincent (IAV) [Phys. Rev. C 32, 431 (1985)] \cite{IAV1985}, Udagawa and Tamura (UT)[Phys. Rev. C 24, 1348 (1981)], \cite{UT1981} and Hussein and McVoy (HM)[Nucl. Phys. A 445, 124 (1985)], \cite{HM1985}. We extend these three-body theories to derive an expression for the fragment yield in the reaction $A (a, b) X$ , where the projectile is $a = x_{1} + x_{2} + b$ . The inclusive breakup cross section is found to be the sum of a generalized four-body form of the elastic breakup cross section plus the inclusive non-elastic breakup cross section which involves the "reaction" cross section of the participant fragments, $x_{1}$ and $x_{2}$ . The final result is similar to the three-body case reviewed in Austern, et al. (Phys. Rep. \textbf{154}, 125 (1987)), \cite{Austern1987}, but with important genuine four-body effects added, both in the elastic breakup cross section, which now contains the full correlations between the participant fragments, and in the inclusive non- elastic breakup. These developments should encourage experimentalists to seek more information about the $x_{1} + x_{2}$ system in the elastic breakup cross section, and to theorists to further develop and extend the surrogate method, based on the inclusive non-elastic breakup part of the $b$ spectrum.
Comments:
14 pages, 1 figure. This paper is based on a talk given by MSH in Cluster2016, Napoli-Italy, May 23 - 27. A shorter version will appear in the proceedings. We have added the DWBA version of the theory through the use of the Faddeev-Yakubovsky equations
Subjects:
Nuclear Theory (nucl-th); Nuclear Experiment (nucl-ex); physics.atm-clus (physics.atm-clus)
arXiv:
1607.05783 [pdf]
2 citations
02
[Submitted on 20 Jul 2016]
Next-to-next-to-leading order Skyrme interaction in nuclear matter: Nuclear bulk quantities at second order in perturbation theory
Kassem Moghrabi
We present the explicit form of the next-to-next-to-leading order (N $^{2}$ LO) Skyrme interaction in momentum space by including the fourth-order gradient potentials to the standard Skyrme interaction. With the N $^{2}$ LO Skyrme interaction, we evaluate the second-order corrections to the nuclear bulk quantities of nuclear matter: equation of state (EoS) of isospin symmetric and pure neutron matter, density-dependent in-medium effective nucleon mass, isospin-asymmetry energy, pressure and incompressibility. These second-order contributions are ultraviolet (UV) divergent due to the zero range character of the interaction and renormalized using the techniques of dimensional regularization (DR) with the minimal subtraction scheme (MS). We adjust the 18 parameters of the interaction by performing a global fit to the nuclear bulk quantities. Besides the too strong dependence $k_{F}^{12}$ of several second-order corrections, a very good reproduction of a realistic nuclear matter saturation curve with all the nuclear bulk quantities in the density region $0.12 < ρ < 0.20$ fm $^{- 3}$ is obtained.
Subjects:
Nuclear Theory (nucl-th)
arXiv:
1607.05829 [pdf]
3 citations
03
[Submitted on 20 Jul 2016]
Structure of the $Λ (1405)$ from Hamiltonian effective field theory
Zhan-Wei Liu🇦🇺 · Jonathan M. M. Hall🇦🇺 · Derek B. Leinweber🇦🇺 · Anthony W. Thomas🇦🇺 · Jia-Jun Wu🇦🇺
The pole structure of the $Λ (1405)$ is examined by fitting the couplings of an underlying Hamiltonian effective field theory to cross sections of $K^{-} p$ scattering in the infinite-volume limit. Finite-volume spectra are then obtained from the theory, and compared to lattice QCD results for the mass of the $Λ (1405)$ . Momentum-dependent, non-separable potentials motivated by the well-known Weinberg-Tomozawa terms are used, with SU(3) flavour symmetry broken in the couplings and masses. In addition, we examine the effect on the behaviour of the spectra from the inclusion of a bare triquark-like isospin-zero basis state. It is found that the cross sections are consistent with the experimental data with two complex poles for the $Λ (1405)$ , regardless of whether a bare baryon basis state is introduced or not. However, it is apparent that the bare baryon is important for describing the results of lattice QCD at high pion masses.
Comments:
10 pages, 8 figures; more contents added based on the referee's comments; accepted by Phys. Rev. D
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Lattice (hep-lat); High Energy Physics — Phenomenology (hep-ph)
arXiv:
1607.05856 [pdf]
PRD(2017)·82 citations
04
[Submitted on 20 Jul 2016]
Effect of isoscalar spin-triplet pairings on spin-isospin responses in $s d -$ shell nuclei
H. Sagawa · T. Suzuki · M. Sasano
The spin magnetic dipole transitions and the neutron-proton spin-spin correlations in $s d -$ shell even-even nuclei with $N = Z$ are investigated using shell model wave functions. The isoscalar spin-triplet pairing correlation provides a substantial quenching effect on the spin magnetic dipole transitions, especially the isovector (IV) ones. Consequently, an enhanced isoscalar spin-triplet pairing interaction influences the proton-neutron spin-spin correlation deduced from the difference between the isoscalar (IS) and the IV sum rule strengths. The effect of the $Δ$ ( $Δ_{33}$ resonance)-hole coupling is examined in the IV spin transition and the spin-spin correlations of the ground states.
Subjects:
Nuclear Theory (nucl-th)
arXiv:
1607.05881 [pdf]
PRC(2016)·14 citations
05
[Submitted on 20 Jul 2016]
The Vlasov formalism for extended relativistic mean field models: the crust-core transition and the stellar matter equation of state
Helena Pais · Constança Providência
The Vlasov formalism is extended to relativistic mean-field hadron models with non-linear terms up to fourth order and applied to the calculation of the crust-core transition density. The effect of the nonlinear $ω ρ$ and $σ ρ$ coupling terms on the crust-core transition density and pressure, and on the macroscopic properties of some families of hadronic stars is investigated. For that purpose, six families of relativistic mean field models are considered. Within each family, the members differ in the symmetry energy behavior. For all the models, the dynamical spinodals are calculated, and the crust-core transition density and pressure, and the neutron star mass-radius relations are obtained. The effect on the star radius of the inclusion of a pasta calculation in the inner crust is discussed. The set of six models that best satisfy terrestrial and observational constraints predicts a radius of 13.6 $\pm$ 0.3 km and a crust thickness of $1.36 \pm 0.06$ km for a 1.4 $M_{⊙}$ star.
Comments:
18 pages, 11 figures, accepted for publication in Phys. Rev. C
Subjects:
Nuclear Theory (nucl-th)
arXiv:
1607.05899 [pdf]
PRC(2016)·98 citations

Affiliations

first authorsco-authorsvia INSPIRE

Theory of inclusive breakup cross section for Borromean nuclei within a four-body spectator model

Next-to-next-to-leading order Skyrme interaction in nuclear matter: Nuclear bulk quantities at second order in perturbation theory

Structure of the Λ(1405) from Hamiltonian effective field theory

Effect of isoscalar spin-triplet pairings on spin-isospin responses in sd− shell nuclei

The Vlasov formalism for extended relativistic mean field models: the crust-core transition and the stellar matter equation of state

Affiliations

Structure of the $Λ (1405)$ from Hamiltonian effective field theory

Effect of isoscalar spin-triplet pairings on spin-isospin responses in $s d -$ shell nuclei