Nuclear Theory·nucl-th

Friday·August 21, 2015

12 papers—8 primary·4 cross-listed

01
Establishing a theory for deuteron induced surrogate reactions
Gregory Potel Aguilar · Filomena M. Nunes · Ian J. Thompson
The goal of this work is to establish on firm grounds a theory for deuteron induced neutron capture reactions. This includes formulating elastic and inelastic breakup in a consistent manner. We describe this process both in post and prior form distorted wave Born approximation, and we apply our method to the 53Nb(d,p)X at Ed =15 MeV and 25 MeV, obtaining a good description of the data. We look at the various partial wave contributions, as well as elastic versus inelastic contributions. We also connect our formulation with transfer to neutron bound states.
nucl-thPRC(2015)·95 citations
02
The Relativistic Three-Body Bound State in Three-Dimensions
M. R. Hadizadeh · Ch. Elster · W. N. Polyzou
Studying of the relativistic three-body bound state in a three-dimensional (3D) approach is a necessary first step in a process to eventually perform scattering calculations at GeV energies, where partial-wave expansions are not useful. To this aim we recently studied relativistic effects in the binding energy and for the first time, obtained the relativistic 3B wave function \cite{Hadizadeh_PRC90}. The relativistic Faddeev integral equations for the bound state are formulated in terms of momentum vectors, and relativistic invariance is incorporated within the framework of Poincaré invariant quantum mechanics.
nucl-thEPJ Web Conf.(2016)·7 citations
03
Hyperon Puzzle, Hadron-Quark Crossover and Massive Neutron Stars
Kota Masuda🇯🇵 · Tetsuo Hatsuda🇯🇵 · Tatsuyuki Takatsuka🇯🇵
Bulk properties of cold and hot neutron stars (NSs) are studied on the basis of the hadron-quark crossover picture where a smooth transition from the hadronic phase to the quark phase takes place at finite baryon density. By using a phenomenological equation of state (EOS) "CRover" which interpolates the two phases at around 3 times the nuclear matter density, it is found that the cold NSs with the gravitational mass larger than 2-solarmass can be sustained. This is in sharp contrast to the case of the first-order hadron-quark transition. The radii of the cold NSs with the CRover EOS are in the narrow range which is insensitive to the NS masses. Due to the stiffening of the EOS induced by the hadron-quark crossover, the central density of the NSs is at most 4 times the nuclear matter density and the hyperon-mixing barely occurs inside the NS core. This constitutes a solution of the long-standing hyperon puzzle. The effect of color superconductivity (CSC) on the NS structures is also examined with the hadron-quark crossover. For the typical strength of the diquark attraction, a slight softening of the EOS due to two-flavor CSC (2SC) takes place and the maximum mass is reduced by about 0.2-solarmass. The CRover EOS is generalized to the supernova matter at finite temperature to describe the hot NSs at birth. The hadron-quark crossover is found to decrease the central temperature of the hot NSs under isentropic condition. The gravitational energy release and the spin-up rate during the contraction from the hot NS to the cold NS are also estimated.
nucl-thastro-ph.HEhep-phEPJA(2016)·66 citations
04
Weak decay of Lambda_c^+ for the study of Lambda(1405) and Lambda(1670)
Kenta Miyahara🇯🇵 · Tetsuo Hyodo🇯🇵 · Eulogio Oset🇪🇸
We study the Lambda_c decay process to pi^+ and the meson-baryon final state for the analysis of Lambda resonances. Considering the Cabibbo-Kobayashi-Maskawa matrix, color suppression, diquark correlation and the kinematical condition, we show that the final meson-baryon state should be in a pure I=0 combination, when the meson-baryon invariant mass is small. Because the I=1 contamination usually makes it difficult to analyze Lambda resonances directly from experiments, the Lambda_c decay is an ideal process to study Lambda resonances. Calculating the final state interaction by chiral unitary approaches, we find that the piSigma invariant mass distributions have the same peak structure in the all charge combination of the piSigma states related to the higher pole of the two poles of the Lambda(1405). Furthermore, we obtain a clear the Lambda(1670) peak structure in the KbarN and etaLambda spectra.
nucl-thhep-phPRC(2015)·72 citations
05
Neutron star structure from QCD
Eduardo S. Fraga🇧🇷 · Aleksi Kurkela🇨🇭 · Aleksi Vuorinen🇫🇮
In this review article, we argue that our current understanding of the thermodynamic properties of cold QCD matter, originating from first principles calculations at high and low densities, can be used to efficiently constrain the macroscopic properties of neutron stars. In particular, we demonstrate that combining state-of-the-art results from Chiral Effective Theory and perturbative QCD with the current bounds on neutron star masses, the Equation of State of neutron star matter can be obtained to an accuracy better than 30% at all densities.
nucl-thastro-ph.HEhep-phEPJA(2016)·58 citations
06
Exploring sd-shell nuclei from two- and three-nucleon interactions with realistic saturation properties
J. Simonis · K. Hebeler · J.D. Holt · J. Menendez · A. Schwenk
We study ground- and excited-state properties of all sd-shell nuclei with neutron and proton numbers 8 <= N,Z <= 20, based on a set of low-resolution two- and three-nucleon interactions that predict realistic saturation properties of nuclear matter. We focus on estimating the theoretical uncertainties due to variation of the resolution scale, the low-energy couplings, as well as from the many-body method. The experimental two-neutron and two-proton separation energies are reasonably well reproduced, with an uncertainty range of about 5 MeV. The first excited 2+ energies also show overall agreement, with a more narrow uncertainty range of about 500 keV. In most cases, this range is dominated by the uncertainties in the Hamiltonian.
nucl-thnucl-exPRC(2016)·114 citations
07
Towards a Faddeev-AGS description of $(d, p)$ reactions with heavy nuclei: Regularizing integrals with Coulomb functions
The TORUS Collaboration: V. Eremenko · L. Hlophe · Ch. Elster · F.M. Nunes · I.J. Thompson · G. Arbanas · J.E. Escher
The repulsive Coulomb force poses severe challenges when describing $(d, p)$ reactions for highly charged nuclei as a three-body problem. Casting Faddeev-AGS equations in a Coulomb basis avoids introducing screening of the Coulomb force. However, momentum space partial-wave $t$ -matrix elements need to be evaluated in this basis. When those $t$ -matrices are separable, the evaluation requires the folding of a form factor, depending on one momentum variable, with a momentum space partial-wave Coulomb function, which has a singular behavior at the external momentum $q$ . We developed an improved regularization scheme to calculate Coulomb distorted form factors as the integral over the Coulomb function and complex nuclear form factors.
nucl-thEPJ Web Conf.(2016)·1 citation
08
Effective Theory of 3H and 3He
Sebastian König🇺🇸 · Harald W. Grießhammer🇺🇸 · H.-W. Hammer🇩🇪 · U. van Kolck🇫🇷
We present a new perturbative expansion for pionless effective field theory with Coulomb interactions in which at leading order the spin-singlet nucleon-nucleon channels are taken in the unitarity limit. Presenting results up to next-to-leading order for the Phillips line and the neutron-deuteron doublet-channel phase shift, we find that a perturbative expansion in the inverse 1S0 scattering lengths converges rapidly. Using a new systematic treatment of the proton-proton sector that isolates the divergence due to one-photon exchange, we renormalize the corresponding contribution to the 3H-3He binding energy splitting and demonstrate that the Coulomb force in pionless EFT is a completely perturbative effect in the trinucleon bound-state regime. In our new expansion, the leading order is exactly isospin-symmetric. At next-to-leading order, we include isospin breaking via the Coulomb force and two-body scattering lengths, and find for the energy splitting (E_B(3He)-E_B(3H))^NLO = (-0.86 +/- 0.17) MeV.
nucl-thJ.Phys.G(2016)·74 citations

Affiliations

first authorsco-authorsvia INSPIRE