Nuclear Theory·nucl-th

Thursday·March 3, 2016

12 papers—4 primary·8 cross-listed

01
Investigating the alpha-clustering on the surface of $^{120}$ Sn via ( $p$ , $p α$ ) reaction and the validity of the factorization approximation
Kazuki Yoshida · Kosho Minomo · Kazuyuki Ogata
The $^{120}$ Sn( $p$ , $p α$ ) $^{116}$ Cd reaction at 392 MeV is investigated with the distorted wave impulse approximation (DWIA) framework. We show that this reaction is very peripheral mainly because of the strong absorption of $α$ by the reaction residue $^{116}$ Cd, and the $α$ -clustering on the nuclear surface can be probed clearly. We investigate also the validity of the so-called factorization approximation that has frequently been used so far. It is shown that the kinematics of $α$ in the nuclear interior region is significantly affected by the distortion of $^{116}$ Cd, but it has no effect on the reaction observables because of the strong absorption in that region.
nucl-thPRC(2016)·43 citations
02
Structure of the number projected BCS wave function
J. Dukelsky · S. Pittel · C. Esebbag
We study the structure of the number projected BCS (PBCS) wave function in the particle-hole basis, displaying its similarities with coupled clusters theory (CCT). The analysis of PBCS together with several modifications suggested by the CCT wave function is carried out for the exactly solvable Richardson model involving a pure pairing hamiltonian acting in a space of equally-spaced doubly-degenerate levels. We point out the limitations of PBCS to describe the non-superconducting regime and suggest possible avenues for improvement.
nucl-thcond-mat.supr-conPRC(2016)·12 citations
03
Constraining the density dependence of the symmetry energy using the multiplicity and average $p_{T}$ ratios of charged pions
M.D. Cozma🇷🇴
The charged pion multiplicity ratio in intermediate energy heavy-ion collisions, a probe of the density dependence of symmetry energy above the saturation point, has been proven in a previous study to be extremely sensitive to the strength of the isovector $Δ$ (1232) potential in nuclear matter. As there is no knowledge, either from theory or experiment, about the magnitude of this quantity, the extraction of constraints on the slope of the symmetry energy at saturation by using exclusively the mentioned observable is hindered at present. It is shown that, by including the ratio of average $p_{T}$ of charged pions $⟨ p_{T}^{(π^{+})} ⟩ / ⟨ p_{T}^{(π^{-})} ⟩$ in the list of fitted observables, the noted problem can be circumvented. A realistic description of this observable requires accounting for the interaction of pions with the dense nuclear matter environment by the incorporation of the so called $S$ -wave and $P$ -wave pion optical potentials. This is performed within the framework of a quantum molecular dynamics transport model that enforces the conservation of the total energy of the system. It is shown that constraints on the slope of the symmetry energy at saturation density and the strength of the $Δ$ (1232) potential can be simultaneously extracted. A symmetry energy with a value of the slope parameter $L >$ 50 MeV is favored, at 1 $σ$ confidence level, from a comparison with published FOPI experimental data. A precise constraint will require experimental data more accurate than presently available, particularly for the charged pion multiplicity ratio, and better knowledge of the density and momentum dependence of the pion potential for the whole range of these two variables probed in intermediate energy heavy-ion collisions.
nucl-thnucl-exPRC(2017)·52 citations
04
Tagged spectator deep-inelastic scattering off the deuteron as a tool to study neutron structure
W. Cosyn🇧🇪 · M. Sargsian🇺🇸
We give an overview of a model to describe deep-inelastic scattering (DIS) off the deuteron with a spectator proton, based on the virtual nucleon approximation (VNA). The model accounts for the final-state interactions (FSI) of the DIS debris with the spectator proton. Values of the rescattering cross section are obtained by fits to high-momentum spectator data. By using the so-called "pole extrapolation method", free neutron structure functions can be obtained by extrapolating low-momentum spectator proton data to the on-shell neutron pole. We apply this method to the BONuS data set and find a surprising Bjorken $x$ dependence, indicating a possible rise of the neutron to proton structure function ratio at high $x$ .
nucl-thnucl-exEPJ Web Conf.(2016)·1 citation

Affiliations

first authorsco-authorsvia INSPIRE

Investigating the alpha-clustering on the surface of 120Sn via (p,pα) reaction and the validity of the factorization approximation

Structure of the number projected BCS wave function

Constraining the density dependence of the symmetry energy using the multiplicity and average pT​ ratios of charged pions

Tagged spectator deep-inelastic scattering off the deuteron as a tool to study neutron structure

Affiliations

Investigating the alpha-clustering on the surface of $^{120}$ Sn via ( $p$ , $p α$ ) reaction and the validity of the factorization approximation

Constraining the density dependence of the symmetry energy using the multiplicity and average $p_{T}$ ratios of charged pions