Nuclear Theory·nucl-th

Monday·April 23, 2018

8 papers—4 primary·4 cross-listed

01
Neck configuration of Cm and Cf nuclei in the fission state within relativistic mean field formalism
M. Bhuyan · B. V. Carlson · S. K. Patra · R. K. Gupta
A correlation is established between the neutron multiplicity and the neutrons number in the fission state of Curium and Californium isotopes within a microscopic study using relativistic mean field formalism. The study includes the isotopes of Cm and Cf nuclei near the valley of stability, and hence is likely to play an important role in the artificial synthesis of superheavy nuclei. The static fission path, the neutron $-$ proton asymmetry, the evolution of the neck and their composition in terms of nucleon numbers are also estimated. We find a maximum ratio for average neutron to proton density, which is about $1.6$ in the breakdown of the liquid $-$ drop picture for $^{248}$ Cm and $^{252}$ Cf. A strong dependence of the neutron $-$ proton asymmetry on the neutron multiplicity in an isotopic chain is also observed.
nucl-thPRC(2019)·2 citations
02
Diffusion monte carlo calculations of three-body systems
Mengjiao Lyu · Zhongzhou Ren · Qihu Lin
Application of diffusion Monte Carlo algorithm in three-body systems is studied. We develop a program and use it to calculate the property of various three-body systems. Regular Coulomb systems such as atoms, molecules and ions are investigated. Calculation is then extended to exotic systems where electrons are replaced by muons. Some nuclei with neutron halos are also calculated as three-body systems consisting of a core and two external nucleons. Our results agree well with experiments and others' work.
nucl-thCPC(2012)·1 citation
03
Quasielastic charged-current neutrino scattering in the scaling model with relativistic effective mass
I. Ruiz Simo🇪🇸 · V.L. Martinez-Consentino🇪🇸 · J.E. Amaro🇪🇸 · E. Ruiz Arriola🇪🇸
We use a recent scaling analysis of the quasielastic electron scattering data from $^{12}$ C to predict the quasielastic charge-changing neutrino scattering cross sections within an uncertainty band. We use a scaling function extracted from a selection of the $(e, e^{'})$ cross section data, and an effective nucleon mass inspired by the relativistic mean-field model of nuclear matter. The corresponding super-scaling analysis with relativistic effective mass (SuSAM*) describes a large amount of the electron data lying inside a phenomenological quasielastic band. The effective mass incorporates the enhancement of the transverse current produced by the relativistic mean field. The scaling function incorporates nuclear effects beyond the impulse approximation, in particular meson-exchange currents and short range correlations producing tails in the scaling function. Besides its simplicity, this model describes the neutrino data as reasonably well as other more sophisticated nuclear models.
nucl-thhep-phPRD(2018)·23 citations
04
Calculating hard probe radiative energy loss beyond soft-gluon approximation: Examining the approximation validity
Bojana Blagojevic🇷🇸 · Magdalena Djordjevic🇷🇸 · Marko Djordjevic🇷🇸
The soft-gluon approximation, which implies that radiated gluon carries away a small fraction of initial parton's energy, is a commonly used assumption in calculating radiative energy loss of high momentum partons traversing QGP created at RHIC and LHC. While soft-gluon approximation is convenient, different theoretical approaches reported significant radiative energy loss of high $p_{⊥}$ partons, thereby questioning its validity. To address this issue, we relaxed the soft-gluon approximation within DGLV formalism. The obtained analytical expressions are quite distinct compared to the soft-gluon case. However, numerical results for the first order in opacity fractional energy loss lead to small differences in predictions for the two cases. The difference in the predicted number of radiated gluons is also small. Moreover, the effect on these two variables has an opposite sign, which when combined results in almost overlapping suppression predictions. Therefore, our results imply that, contrary to the commonly held doubts, the soft-gluon approximation in practice works surprisingly well in DGLV formalism. Finally, we also discuss generalizing this relaxation in the dynamical QCD medium, which suggests a more general applicability of the conclusions obtained here.
nucl-thhep-phPRC(2019)·29 citations
05
$J / ψ \to γ η^{'} π^{+} π^{-}$ and the structure observed around the $p ˉ p$ threshold
Ling-Yun Dai🇨🇳 · Johann Haidenbauer🇩🇪 · Ulf-G. Meißner🇩🇪
We analyze the origin of the structure observed in the reaction $J / ψ \to γ η^{'} π^{+} π^{-}$ for $η^{'} π^{+} π^{-}$ invariant masses close to the antiproton-proton ( $p ˉ p$ ) threshold, commonly associated with the $X (1835)$ resonance. Specifically, we explore the effect of a possible contribution from the two-step process $J / ψ \to γ N ˉ N \to γ η^{'} π^{+} π^{-}$ . The calculation is performed in distorted-wave Born approximation which allows an appropriate inclusion of the $N ˉ N$ interaction in the transition amplitude. The $N ˉ N$ amplitude itself is generated from a corresponding potential recently derived within chiral effective field theory. We are able to reproduce the measured spectra for the reactions $J / ψ \to γ p ˉ p$ and $J / ψ \to γ η^{'} π^{+} π^{-}$ for invariant masses around the $p ˉ p$ threshold. The structure seen in the $η^{'} π^{+} π^{-}$ spectrum emerges as a threshold effect due to the opening of the $p ˉ p$ channel.
↳ hep-phnucl-thPRD(2018)·20 citations
06
Nucleon Mass Sum Rule Violation in QCD and Confinement
Gouranga C Nayak🇺🇸
In this paper we show that for a nucleon at rest if the quarks and/or antiquarks are in motion inside the nucleon producing chromo-magnetic field then the mass sum rule in QCD is violated when the confinement potential energy at large distance $r$ rises linearly with $r$ (or faster). Hence we find that the mass of the nucleon at rest is not equal to the mass-energy of all the quarks plus antiquarks plus gluons inside the nucleon if there exists chromo-magnetic field inside the nucleon and the confinement potential energy at large distance $r$ rises linearly with $r$ (or faster).
↳ hep-phhep-latnucl-th3 citations
07
Partial-Wave Analysis of $γ p \to K^{+} Λ$ using a multichannel framework
B. C. Hunt🇺🇸 · D. M. Manley🇺🇸
Results from a partial-wave analysis of the reaction $γ p \to K^{+} Λ$ are presented. The reaction is dominated by the $S_{11} (1650)$ and $P_{13} (1720)$ resonances at low energies and by $P_{13} (1900)$ at higher energies. There are small contributions from all amplitudes up to and including $G_{17}$ , with $F_{17}$ necessary for obtaining a good fit of several of the spin observables. We find evidence for $P_{11}$ (1880), $D_{13}$ (2120), and $D_{15}$ (2080) resonances, as well as a possible $F_{17}$ resonance near 2300 MeV, which is expected from quark-model predictions. Some predictions for $γ n \to K^{0} Λ$ are also included.
↳ nucl-exnucl-thPRC(2019)·20 citations
08
Elliptic flow and $R_{AA}$ of D mesons at FAIR comparing the UrQMD hybrid model and the coarse-graining approach
Gabriele Inghirami🇩🇪 · Hendrik van Hees🇩🇪 · Stephan Endres🇩🇪 · Juan M. Torres-Rincon🇺🇸 · Marcus Bleicher🇩🇪
We present a study of the elliptic flow and $R_{AA}$ of D and anti-D mesons in Au+Au collisions at FAIR energies. We propagate the charm quarks and the D mesons following a previously applied Langevin dynamics. The evolution of the background medium is modeled in two different ways: (I) we use the UrQMD hydrodynamics + Boltzmann transport hybrid approach including a phase transition to QGP and (II) with the coarse-graining approach employing also an equation of state with QGP. The latter approach has previously been used to describe di-lepton data at various energies very successfully. This comparison allows us to explore the effects of partial thermalization and viscous effects on the charm propagation. We explore the centrality dependencies of the collisions, the variation of the decoupling temperature and various hadronization parameters. We find that the initial partonic phase is responsible for the creation of most of the D mesons elliptic flow and that the subsequent hadronic interactions seem to play only a minor role. This indicates that D mesons elliptic flow is a smoking gun for a partonic phase at FAIR energies. However, the results suggest that the magnitude and the details of the elliptic flow strongly depend on the dynamics of the medium and on the hadronization procedure, which is related to the medium properties as well. Therefore, even at FAIR energies the charm quark might constitute a very useful tool to probe the Quark-Gluon Plasma and investigate its physics.
↳ hep-phhep-exnucl-thEPJC(2019)·10 citations

Affiliations

first authorsco-authorsvia INSPIRE