Nuclear Theory·nucl-th

Wednesday·April 12, 2017

9 papers—6 primary·3 cross-listed

01
Effects of enhanced bulk viscosity near the QCD critical point
Akihiko Monnai🇫🇷 · Swagato Mukherjee🇺🇸 · Yi Yin🇺🇸
Search for the conjectured QCD critical point is one of the major scientific goals for the Beam Energy Scan program at RHIC. The growth of the correlation length is a universal feature for systems near criticality, and bulk viscosity exhibits the strongest dependence on the correlation length. We investigate its effects using a relativistic hydrodynamic model to find that rapidity distributions of charged particles and net baryon number are visibly modified if the fireball passes through the vicinity of the QCD critical point on the phase diagram. We also discuss how critical modification of dilepton emission rate may leave imprints on invariant mass spectra.
nucl-thhep-phnucl-exNPA(2017)·6 citations
02
Correlated-Gaussian approach to linear-chain states -Case of four $α$ -particles-
Y. Suzuki · W. Horiuchi
We show that correlated Gaussians with good angular momentum and parity provide flexible basis functions for specific elongated shape. As its application we study linear-chain states of four-alpha particles in variation-after-projection calculations in which all the matrix elements are evaluated analytically. We find possible chain states for $J = 0^{+}$ , $2^{+}$ , $4^{+}$ and perhaps $6^{+}$ with the bandhead energy being about 33 MeV from the ground state of $^{16}$ O. No chain states with $J \geq 8$ are found. The nature of the rotational sequence of the chain states is clarified in contrast to a rigid-body rotation. The quadrupole deformation parameters estimated from the chain states increase from 0.59 to 1.07 for $2^{+}$ to $6^{+}$ . This work suggests undeveloped fields for the correlated Gaussians beyond those problems which have hitherto been solved successfully.
nucl-thPRC(2017)·12 citations
03
Structural Properties of Finite and Infinite Nuclear Systems and Related Phenomena
Subrata Kumar Biswal
In the present thesis, we have carried a thorough investigation of nuclear structure properties. We start our investigation from the study of the magic property of nucleus in the super -heavy region. We know the magic combination of proton and neutron in the light and medium heavy region. But in the super-heavy region, it is still unclear. We applied SEI (simple effective interaction ) and RMF (relativistic mean field ) formalism with a different parameter sets to predict the magic combinations and it turned out Z=114, 120, 126 with N=184. We have also studied theisoscalar giant monopole resonance energy of nucleus of Z=114, 120,126, with scaling and constrained method using RETF formalism. Isoscalar giant monopole resonance (ISGMR) is also known as the breathing mode. We have a developed a new constrained type calculation for the ISGMR and IVGDR. Effects of delta meson on the neutron system also discuses extensively.
nucl-thDAE Symp.Nucl.Phys.(2016)·0 citations
04
Elastic Scattering Phenomenology
R.S. Mackintosh
We argue that, in many situations, fits to elastic scattering data that were historically, and frequently still are, considered `good', are not justifiably so describable. Information about the dynamics of nucleon-nucleus and nucleus-nucleus scattering is lost when elastic scattering phenomenology is insufficiently ambitious. It is argued that in many situations, an alternative approach is appropriate for the phenomenology of nuclear elastic scattering of nucleons and other light nuclei. The approach affords an appropriate means of evaluating folding models, one that fully exploits available empirical data. It is particularly applicable for nucleons and other light ions.
nucl-thnucl-exEPJA(2017)·4 citations
05
Bayesian truncation errors in chiral effective field theory: nucleon-nucleon observables
J.A. Melendez · S. Wesolowski · R.J. Furnstahl
Chiral effective field theory (EFT) predictions are necessarily truncated at some order in the EFT expansion, which induces an error that must be quantified for robust statistical comparisons to experiment. In previous work, a Bayesian model for truncation errors of perturbative expansions was adapted to EFTs. The model yields posterior probability distribution functions (pdfs) for these errors based on expectations of naturalness encoded in Bayesian priors and the observed order-by-order convergence pattern of the EFT. A first application was made to chiral EFT for neutron-proton scattering using the semi-local potentials of Epelbaum, Krebs, and Meißner (EKM). Here we extend this application to consider a larger set of regulator parameters, energies, and observables as a general example of a statistical approach to truncation errors. The Bayesian approach allows for statistical validations of the assumptions and enables the calculation of posterior pdfs for the EFT breakdown scale. The statistical model is validated for EKM potentials whose convergence behavior is not distorted by regulator artifacts. For these cases, the posterior for the breakdown scale is consistent with EKM assumptions.
nucl-thhep-phnucl-exphysics.data-anPRC(2017)·188 citations
06
Goodness of Generalized Seniority in Semi-magic Nuclei
Ashok Kumar Jain · Bhoomika Maheshwari
Symmetry plays an important role in understanding the nuclear structure properties from the rotation of a nucleus to the spin, parity and isospin of nuclear states. This simplifies the complexity of the nuclear problems in one way or the other. Seniority is also a well known quantum number which arises due to the symmetry in the pairing interaction of nuclei. We present empirical as well as theoretical evidences based on decay rates which support the goodness of seniority at higher spins as well as in nrich or, n-deficient nuclei. We find that the generalized seniority governs the identical trends of high-spin isomers in different semi-magic chains, where different set of nucleon orbitals from different valence spaces are involved.
nucl-thNucl.Phys.Rev.(2017)·8 citations
07
3-D Glasma initial state from small-x evolution
Björn Schenke🇺🇸 · Sören Schlichting🇺🇸
We present an ab-initio approach to compute the longitudinal dependence of the initial state in heavy-ion collisions by including small-x evolution of the nuclear gluon distributions. Extending the IP-Glasma model by including JIMWLK rapidity evolution, we compute event-by-event rapidity distributions of produced gluons and the early time energy momentum tensor as a function of space-time rapidity and transverse coordinates. We show how the effects of small-x evolution manifest themselves in longitudinal (rapidity) correlations of event-by-event multiplicities and transverse geometry and compare our results to various phenomenological models and experimental observations.
↳ hep-phnucl-thNPA(2017)·1 citation
08
Precise measurement of alpha_K and alpha_T for the 109.3-keV M4 transition in 125Te: Test of internal-conversion theory
N. Nica · J.C. Hardy · V.E. Iacob · T.A. Werke · C.M. Folden III · K. Ofodile · M.B. Trzhaskovskaya
We have measured the K-shell and total internal conversion coefficients (ICCs), alpha_K and alpha_T, for the 109.3-keV M4 transition in 125Te to be 185.0(40) and 350.0(38), respectively. Previously this transition's ICCs were considered anomalous, with alpha values lying below calculated values. When compared with Dirac-Fock calculations, our new results show good agreement. The alpha_K result agrees well with the version of the theory that takes account of the K-shell atomic vacancy and disagrees with the one that does not. This is consistent with our conclusion drawn from a series of high multipolarity transitions.
↳ nucl-exnucl-thPRC(2017)·4 citations
09
Pion radiative weak decay from the instanton vacuum
Sang-In Shim🇰🇷 · Hyun-Chul Kim🇰🇷
We investigate the vector and axial-vector form factors for the pion radiative weak decays $π^{+} \to e^{+} ν_{e} γ$ and $π^{+} \to e^{+} ν_{e} e^{+} e^{-}$ , based on the gauged effective chiral action from the instanton vacuum in the large $N_{c}$ limit. The nonlocal contributions, which arise from the gauging of the action, enhance the vector form factor by about $20 %$ , whereas the axial-vector form factor is reduced by almost $30 %$ . Both the results for the vector and axial-vector form factors at the zero momentum transfer are in good agreement with the experimental data. The dependence of the form factors on the momentum transfer is also studied. The slope parameters are computed and compared with other works.
↳ hep-phhep-exnucl-thPLB(2017)·5 citations

Affiliations

first authorsco-authorsvia INSPIRE