Nuclear Theory·nucl-th

Friday·September 25, 2015

10 papers—6 primary·4 cross-listed

01
Microscopic optical potential for exotic isotopes from chiral effective field theory
J. W. Holt · N. Kaiser · G. A. Miller
We compute the isospin-asymmetry dependence of microscopic optical model potentials from realistic chiral two- and three-body interactions over a range of resolution scales $Λ ≃ 400 - 500$ \,MeV. We show that at moderate projectile energies, $E_{inv} = 110 - 200$ \,MeV, the real isovector part of the optical potential changes sign, a phenomenon referred to as isospin inversion. We also extract the strength and energy dependence of the imaginary isovector optical potential and find no evidence for an analogous phenomenon over the range of energies, $E \leq 200$ \,MeV, considered in the present work. Finally, we compute for the first time the leading corrections to the Lane parametrization for the isospin-asymmetry dependence of the optical potential and observe an enhanced importance at low scattering energies.
nucl-thPRC(2016)·48 citations
02
Charge, neutron, and weak size of the atomic nucleus
G. Hagen · A. Ekström · C. Forssén · G. R. Jansen · W. Nazarewicz · T. Papenbrock · K. A. Wendt · S. Bacca · N. Barnea · B. Carlsson · C. Drischler · K. Hebeler and 5 other authors
What is the size of the atomic nucleus? This deceivably simple question is difficult to answer. While the electric charge distributions in atomic nuclei were measured accurately already half a century ago, our knowledge of the distribution of neutrons is still deficient. In addition to constraining the size of atomic nuclei, the neutron distribution also impacts the number of nuclei that can exist and the size of neutron stars. We present an ab initio calculation of the neutron distribution of the neutron-rich nucleus $^{48}$ Ca. We show that the neutron skin (difference between radii of neutron and proton distributions) is significantly smaller than previously thought. We also make predictions for the electric dipole polarizability and the weak form factor; both quantities are currently targeted by precision measurements. Based on ab initio results for $^{48}$ Ca, we provide a constraint on the size of a neutron star.
nucl-thnucl-exNat.Phys.(2015)·379 citations
03
Double scattering production of two $ρ^{0}$ mesons in UPC
Mariola Kłusek-Gawenda🇵🇱 · Antoni Szczurek🇵🇱
We review our recent results for double-scattering mechanism in the exclusive $AA \to AA ρ^{0} ρ^{0}$ reaction in ultrarelativistic ultraperipheral heavy ion collisions. The cross section for single and double- $ρ^{0}$ production is calculated in the impact parameter space equivalent photon approximation. We compare the results of our calculation with the STAR and ALICE Collaboration results on one $ρ^{0} (770)$ meson and four-charged-pion production.
nucl-thhep-phActa Phys.Polon.Supp.(2015)·0 citations
04
Hybrid method to resolve the neutrino mass hierarchy by supernova (anti)neutrino induced reactions
D. Vale🇭🇷 · T. Rauscher🇬🇧 · N. Paar🇭🇷
We introduce a hybrid method to determine the neutrino mass hierarchy by simultaneous measurements of responses of at least two detectors to antineutrino and neutrino fluxes from accretion and cooling phases of core-collapse supernovae. The (anti)neutrino-nucleus cross sections for $^{56}$ Fe and $^{208}$ Pb are calculated in the framework of the relativistic nuclear energy density functional and weak interaction Hamiltonian, while the cross sections for inelastic scattering on free protons $p (ν ˉ_{e}, e^{+}) n$ are obtained using heavy-baryon chiral perturbation theory. The modelling of (anti)neutrino fluxes emitted from a protoneutron star in a core-collapse supernova include collective and Mikheyev-Smirnov-Wolfenstein effects inside the exploding star. The particle emission rates from the elementary decay modes of the daughter nuclei are calculated for normal and inverted neutrino mass hierarchy. It is shown that simultaneous use of (anti)neutrino detectors with different target material allows to determine the neutrino mass hierarchy from the ratios of $ν_{e}$ - and $ν ˉ_{e}$ -induced particle emissions. This hybrid method favors neutrinos from the supernova cooling phase and the implementation of detectors with heavier target nuclei ( $^{208}$ Pb) for the neutrino sector, while for antineutrinos the use of free protons in mineral oil or water is the appropriate choice.
nucl-thastro-ph.IMastro-ph.SRhep-ex+1JCAP(2016)·12 citations
05
Estimating $η / s$ of QCD matter at high baryon densities
Iu. Karpenko🇺🇦 · M. Bleicher🇩🇪 · P. Huovinen🇩🇪 · H. Petersen🇩🇪
We report on the application of a cascade + viscous hydro + cascade model for heavy ion collisions in the RHIC Beam Energy Scan range, $s_{NN} = 6.3 \dots 200$ GeV. By constraining model parameters to reproduce the data we find that the effective(average) value of the shear viscosity over entropy density ratio $η / s$ decreases from 0.2 to 0.08 when collision energy grows from $s_{NN} \approx 7$ to 39 GeV.
nucl-thhep-phJ.Phys.Conf.Ser.(2016)·2 citations
06
Fluctuations of harmonic and radial flow in heavy ion collisions with principal components
Aleksas Mazeliauskas🇺🇸 · Derek Teaney🇺🇸
We analyze the spectrum of harmonic flow, $v_{n} (p_{T})$ for $n = 0 - 5$ , in event-by-event hydrodynamic simulations of Pb+Pb collisions at the CERN Large Hadron Collider ( $s_{N N} = 2.76 TeV$ ) with principal component analysis (PCA). The PCA procedure finds two dominant contributions to the two-particle correlation function. The leading component is identified with the event plane $v_{n} (p_{T})$ , while the subleading component is responsible for factorization breaking in hydrodynamics. For $v_{0}$ , $v_{1}$ , and $v_{3}$ the subleading flow is a response to the radial excitation of the corresponding eccentricity. By contrast, for $v_{2}$ the subleading flow in \emph{peripheral collisions} is dominated by the nonlinear mixing between the leading elliptic flow and radial flow fluctuations. In the $v_{2}$ case, the sub-sub-leading mode more closely reflects the response to the radial excitation of $ε_{2}$ . A consequence of this picture is that the elliptic flow fluctuations and factorization breaking change rapidly with centrality, and in central collisions (where the leading $v_{2}$ is small and nonlinear effects can be neglected) the subsub-leading mode becomes important. Radial flow fluctuations and nonlinear mixing also play a significant role in the factorization breaking of $v_{4}$ and $v_{5}$ . We construct good geometric predictors for the orientation and magnitudes of the leading and subleading flows based on a linear response to the geometry, and a quadratic mixing between the leading principal components. Finally, we suggest a set of measurements involving three point correlations which can experimentally corroborate the nonlinear mixing of radial and elliptic flow and its important contribution to factorization breaking as a function of centrality.
nucl-thPRC(2016)·65 citations

Affiliations

first authorsco-authorsvia INSPIRE

Microscopic optical potential for exotic isotopes from chiral effective field theory

Charge, neutron, and weak size of the atomic nucleus

Double scattering production of two ρ0 mesons in UPC

Hybrid method to resolve the neutrino mass hierarchy by supernova (anti)neutrino induced reactions

Estimating η/s of QCD matter at high baryon densities

Fluctuations of harmonic and radial flow in heavy ion collisions with principal components

Affiliations

Double scattering production of two $ρ^{0}$ mesons in UPC

Estimating $η / s$ of QCD matter at high baryon densities