Nuclear Theory·nucl-th

Tuesday·March 3, 2020

11 papers—5 primary·6 cross-listed

01
Connecting far-from-equilibrium hydrodynamics to resummed transport coefficients and attractors
Gabriel S. Denicol (Niteroi, Fluminense U.)🇧🇷 · Jorge Noronha (Illinois U., Urbana)🇺🇸
We investigate whether hydrodynamic attractors are present in simulations of the quark-gluon plasma formed in heavy-ion collisions. We argue that Lagrangian schemes to solve the relativistic viscous fluid equations can be particularly useful to characterize the properties of attractors in heavy ion collisions. Preliminary results are shown in Israel-Stewart theory to support such a claim. We also discuss how to perform the slow-roll expansion in Israel-Stewart theory undergoing a general flow, which naturally leads to the definition of a resummed shear viscosity coefficient that depends on the gradients of the hydrodynamic fields.
nucl-thNPA(2021)·19 citations
02
Neutron-rich matter in atomic nuclei and neutron stars
Claudia Gonzalez-Boquera🇪🇸
The proper understanding of the equation of state (EoS) of highly asymmetric nuclear matter is essential when studying systems such as neutron stars (NSs). Using zero-range Skyrme interactions and finite-range interactions such as Gogny forces, momentum-dependent interactions (MDI) and simple effective interactions (SEI), we analyze the properties of the EoS and the influence they may have on the calculations for NSs. We study the convergence properties of the Taylor series expansion of the EoS in powers of the isospin asymmetry and the accuracy of the results for $β$ -stable nuclear matter when it is computed using the Taylor expansion of the EoS. The NS mass-radius relation for Skyrme and finite-range interactions is also analyzed. As none of the existing parametrizations of the standard Gogny D1 interaction are able to provide an NS inside the observational constraints, we propose a new parametrization, which we name D1M $^{*}$ , that is able to provide NSs of $2 M_{⊙}$ while still providing the same good description of finite nuclei as D1M. A parametrization D1M $^{**}$ is also presented, which is fitted similarly as D1M $^{*}$ and provides NSs up to $1.91 M_{⊙}$ . An accurate determination of the core-crust transition point is necessary for the modeling of NSs for astrophysical purposes. We estimate the core-crust transition in NSs by finding where the nuclear matter in the core is unstable against fluctuations of the density. To do that, we employ two methods, the thermodynamical method and the dynamical method for zero-range and finite-range interactions. To apply the dynamical method to finite-range forces, we have explicitly derived the expression of the energy curvature matrix in momentum space. Finally, the NS crustal properties, moment of inertia and tidal deformability are thoroughly analyzed using Skyrme and finite-range interactions.
nucl-th4 citations
03
The possibility to study in-medium modification of $J / ψ$ mesons from their photoproduction on nuclei near threshold in the case of presence of the LHCb pentaquark states $P_{c}^{+}$ in this photoproduction
E. Ya. Paryev🇷🇺
We study the $J / ψ$ photoproduction from nuclei in the near-threshold beam energy region of $E_{γ}$ =5--11 GeV within the nuclear spectral function approach by considering incoherent direct ( $γ N \to J / ψ N$ ) and two-step ( $γ p \to P_{c}^{+} (4312)$ , $P_{c}^{+} (4312) \to J / ψ p$ ; $γ p \to P_{c}^{+} (4440)$ , $P_{c}^{+} (4440) \to J / ψ p$ ; $γ p \to P_{c}^{+} (4457)$ , $P_{c}^{+} (4457) \to J / ψ p$ ) $J / ψ$ production processes. We calculate the absolute excitation functions for the non-resonant and resonant production of $J / ψ$ mesons off $^{12}$ C and $^{208}$ Pb target nuclei within the different scenarios for in-medium modification of the directly photoproduced $J / ψ$ mesons and for branching ratios of the decays $P_{c}^{+} (4312) \to J / ψ p$ , $P_{c}^{+} (4440) \to J / ψ p$ and $P_{c}^{+} (4457) \to J / ψ p$ . We show that the non-resonant subthreshold $J / ψ$ production in $γ A$ reactions reveals some sensitivity to employed in-medium modification scenarios for $J / ψ$ mesons, which is not masked by the resonantly produced $J / ψ$ mesons, only if above branching ratios are less than 5\%. We also demonstrate that if these branching ratios more than 5\% then the presence of the $P_{c}^{+} (4312)$ , $P_{c}^{+} (4440)$ and $P_{c}^{+} (4457)$ resonances in $J / ψ$ photoproduction on nuclei produces above threshold additional enhancements in the behavior of the total $J / ψ$ creation cross section on nuclei, which could be also studied in the future JLab experiments at the CEBAF facility to provide both further evidence for their existence and valuable information on their nature.
nucl-thnucl-exNPA(2020)·9 citations
04
The single-particle unit for alpha decay
Chong Qi · Roberto Liotta · Ramon Wyss
A salient feature of quantum mechanics is the inherent property of collective quantum motion, when apparent independent quasiparticles move in highly correlated trajectories, resulting in strongly enhanced transition probabilities. To assess the extend of a collective quantity requires an appropriate definition of the uncorrelated average motion, often expressed by single particle units. A well known example in nuclear physics is the Weisskopf unit for electromagnetic transitions which reveals different aspects of collective motion. In this paper we define the corresponding single particle unit for alpha decay following Weisskopf's derivations. We evaluate the alpha decay amplitude as induced by four uncorrelated/non-interacting protons and neutrons and compare it with the one extracted from observed decay rates. Our definition elucidates the collectivity in alpha decay and facilitates an unified description of all alpha decay processes along the nuclear chart. Our formalism is also applicable to other particle decay processes.
nucl-thnucl-exPLB(2021)·7 citations
05
Microscopic description of the self-conjugate $^{108}$ Xe and $^{104}$ Te $α$ -decay chain
F. Mercier🇫🇷 · J. Zhao🇨🇳 · R.-D Lasseri🇫🇷 · J.-P. Ebran🇫🇷 · E. Khan🇫🇷 · T. Niksic🇭🇷 · D. Vretenar🇭🇷
A microscopic calculation of half-lives for the recently observed $^{108}$ Xe $\to$ $^{104}$ Te $\to$ $^{100}$ Sn $α$ -decay chain is performed using a self-consistent framework based on energy density functionals. The relativistic density functional DD-PC1 and a separable pairing interaction of finite range are used to compute axially-symmetric deformation energy surfaces of $^{104}$ Te and $^{108}$ Xe as functions of quadrupole, octupole and hexadecupole collective coordinates. Dynamic least-action paths are determined that trace the $α$ -particle emission from the equilibrium deformation to the point of scission. The calculated half-lives: 197 ns for $^{104}$ Te and 50 $μ$ s for $^{108}$ Xe, are compared to recent experimental values of the half-lives of superallowed $α$ -decay of $^{104}$ Te: $< 18$ ns, and $^{108}$ Xe: 58 $_{- 23}^{+ 106}$ $μ$ s.
nucl-thPRC(2020)·15 citations

Affiliations

first authorsco-authorsvia INSPIRE

Connecting far-from-equilibrium hydrodynamics to resummed transport coefficients and attractors

Neutron-rich matter in atomic nuclei and neutron stars

The possibility to study in-medium modification of J/ψ mesons from their photoproduction on nuclei near threshold in the case of presence of the LHCb pentaquark states Pc+​ in this photoproduction

The single-particle unit for alpha decay

Microscopic description of the self-conjugate 108Xe and 104Te α-decay chain

Affiliations

The possibility to study in-medium modification of $J / ψ$ mesons from their photoproduction on nuclei near threshold in the case of presence of the LHCb pentaquark states $P_{c}^{+}$ in this photoproduction

Microscopic description of the self-conjugate $^{108}$ Xe and $^{104}$ Te $α$ -decay chain