Nuclear Theory·nucl-th

Tuesday·May 26, 2020

10 papers—4 primary·6 cross-listed

01
Power-law intensity distribution in $γ$ -decay cascades -- Nuclear Structure as a Scale-Free Random Network
Keisuke Fujii · Julian C. Berengut
By modeling the transition paths of the nuclear $γ$ -decay cascade using a scale-free random network, we uncover a universal power-law distribution of $γ$ -ray intensity $ρ_{I} (I) \propto I^{- 2}$ , with $I$ the $γ$ -ray intensity of each transition. This property is consistently observed for all datasets with a sufficient number of $γ$ -ray intensity entries in the National Nuclear Data Center database, regardless of the reaction type or nuclei involved. In addition, we perform numerical simulations which support the model's predictions of level population density.
nucl-thPRL(2021)·2 citations
02
Effective field theory for deformed odd-mass nuclei
T. Papenbrock · H. A. Weidenmüller
We develop an effective field theory (EFT) for deformed odd-mass nuclei. These are described as an axially symmetric core to which a nucleon is coupled. In the coordinate system fixed to the core the nucleon is subject to an axially symmetric potential. Power counting is based on the separation of scales between low-lying rotations and higher-lying states of the core. In leading order, core and nucleon are coupled by universal derivative terms. These comprise a covariant derivative and gauge potentials which account for Coriolis forces and relate to Berry-phase phenomena. At leading order, the EFT combines the particle-rotor and Nilsson models. We work out the EFT up to next-to-leading order and illustrate the results in $^{239}$ Pu and $^{187}$ Os. At leading order, odd-mass nuclei with rotational band heads that are close in energy and differ by one unit of angular momentum are triaxially deformed. For band heads that are well separated in energy, triaxiality becomes a subleading effect. The EFT developed in this paper presents a model-independent approach to the particle-rotor system that is capable of systematic improvement.
nucl-thPRC(2020)·15 citations
03
Finite size effect on Dissociation and Diffusion of chiral partners in Nambu-Jona-Lasinio model
Paramita Deb🇮🇳 · Sabyasachi Ghosh🇮🇳 · Jai Prakash🇮🇳 · Santosh Kumar Das🇮🇳 · Raghava Varma🇮🇳
Along with masses of pion and sigma meson modes, their dissociation into quark medium provide a detail spectral structures of the chiral partners. Present article has studied a finite size effect on that detail structure of chiral partners by using the framework of Nambu-Jona-Lasinio model. Through this dissociation mechanism, their diffusions and conductions are also studied. The masses, widths, diffusion coefficients, conductivities of chiral partners are merged at different temperatures in restore phase of chiral symmetry, but merging points of all are shifted in lower temperature, when one introduce finite size effect into the picture. The strengths of diffusions and conductions are also reduced due to finite size consideration.
nucl-thhep-phCPC(2022)·5 citations
04
Scattering Observables from One- and Two-Body Densities: Formalism and Application to $γ^{3}$ He Scattering
Harald W. Griesshammer (George Washington U.) · Judith A. McGovern (U. of Manchester) · Andreas Nogga (FZ Jülich) · Daniel R. Phillips (Ohio U.)
We introduce the transition-density formalism, an efficient and general method for calculating the interaction of external probes with light nuclei. One- and two-body transition densities that encode the nuclear structure of the target are evaluated once and stored. They are then convoluted with an interaction kernel to produce amplitudes, and hence observables. By choosing different kernels, the same densities can be used for any reaction in which a probe interacts perturbatively with the target. The method therefore exploits the factorisation between nuclear structure and interaction kernel that occurs in such processes. We study in detail the convergence in the number of partial waves for matrix elements relevant in elastic Compton scattering on $^{3}$ He. The results are fully consistent with our previous calculations in Chiral Effective Field Theory. But the new approach is markedly more computationally efficient, which facilitates the inclusion of more partial-wave channels in the calculation. We also discuss the usefulness of the transition-density method for other nuclei and reactions. Calculations of elastic Compton scattering on heavier targets like $^{4}$ He are straightforward extensions of this study, since the same interaction kernels are used. And the generality of the formalism means that our $^{3}$ He densities can be used to evaluate any $^{3}$ He elastic-scattering observable with contributions from one- and two-body operators. They are available at https://datapub.fz-juelich.de/anogga.
nucl-thFew Body Syst.(2020)·10 citations
05
Decay of the pseudoscalar glueball into vector, axial-vector, scalar and pseudoscalar mesons
Walaa I. Eshraim🇦🇪
We resume the investigation of the ground-state pseudoscalar glueball, $J^{P C} = 0^{-+}$ , by computing its two- and three-body decays into vector and axial-vector quark-antiquark meson fields additional to scalar and pseudoscalar mesons through the construction of an interaction chiral Lagrangian that produces these decays. We evaluate the branching ratio, via a parameter-free calculation, by setting the mass of the pseudoscalar glueball to $2.6$ GeV as predicted by lattice QCD simulations. We duplicate the computation for the branching ratios for a pseudoscalar glueball mass $2.37$ GeV which matches to the measured mass of the resonance $X (2370)$ in the BESIII experiment. The present channels and states are potentially reached and are interesting for the running BESIII and Belle-II experiments and the planned PANDA experiment at FAIR/GSI which will be able to detect the pseudoscalar glueball within the accessible energy range.
↳ hep-phnucl-thEPJC(2023)·10 citations
06
Nonlinear Constraints on Relativistic Fluids Far From Equilibrium
Fabio S. Bemfica🇧🇷 · Marcelo M. Disconzi🇺🇸 · Vu Hoang🇺🇸 · Jorge Noronha🇺🇸 · Maria Radosz🇺🇸
New constraints are found that must necessarily hold for Israel-Stewart-like theories of fluid dynamics to be causal far away from equilibrium. Conditions that are sufficient to ensure causality, local existence, and uniqueness of solutions in these theories are also presented. Our results hold in the full nonlinear regime, taking into account bulk and shear viscosities (at zero chemical potential), without any simplifying symmetry or near-equilibrium assumptions. Our findings provide fundamental constraints on the magnitude of viscous corrections in fluid dynamics far from equilibrium.
↳ hep-thgr-qcmath-phmath.MP+2PRL(2021)·129 citations
07
Isovector parton distribution functions of the proton on a superfine lattice
Zhouyou Fan🇺🇸 · Xiang Gao🇺🇸 · Ruizi Li🇺🇸 · Huey-Wen Lin🇺🇸 · Nikhil Karthik🇺🇸 · Swagato Mukherjee🇺🇸 · Peter Petreczky🇺🇸 · Sergey Syritsyn🇺🇸 · Yi-Bo Yang🇨🇳 · Rui Zhang🇺🇸
We study isovector unpolarized and helicity parton distribution functions (PDF) of the proton within the framework of Large Momentum Effective Theory. We use a gauge ensemble, generated by the MILC Collaboration, with a superfine lattice spacing of $0.042$ fm and a pion mass of $310$ MeV, enabling us to simultaneously reach sub-fermi spatial separations and larger nucleon momenta. We compare the spatial dependence of quasi-PDF matrix elements in different renormalization schemes with the corresponding results of the global fits, obtained using 1-loop perturbative matching. We present determinations of the first four moments of the unpolarized and helicity PDFs of proton from the Ioffe-time dependence of the isovector matrix elements, obtained by employing a ratio-based renormalization scheme.
↳ hep-lathep-phnucl-exnucl-thPRD(2020)·81 citations
08
Low-Dimensional Fluctuations and Pseudogap in Gaudin-Yang Fermi Gases
Hiroyuki Tajima · Shoichiro Tsutsui · Takahiro M. Doi
Pseudogap is a ubiquitous phenomenon in strongly correlated systems such as high- $T_{c}$ superconductors, ultracold atoms and nuclear physics. While pairing fluctuations inducing the pseudogap are known to be enhanced in low-dimensional systems, such effects have not been explored well in one of the most fundamental 1D models, that is, Gaudin-Yang model. In this work, we show that the pseudogap effect can be visible in the single-particle excitation in this system using a diagrammatic approach. Fermionic single-particle spectra exhibit a unique crossover from the double-particle dispersion to pseudogap state with increasing the attractive interaction and the number density at finite temperature. Surprisingly, our results of thermodynamic quantities in unpolarized and polarized gases show an excellent agreement with the recent quantum Monte Carlo and complex Langevin results, even in the region where the pseudogap appears.
↳ cond-mat.quant-gascond-mat.str-elcond-mat.supr-connucl-thPRResearch(2020)·4 citations
09
Analytical determination of the structure of the outer crust of a cold nonaccreted neutron star: extension to strongly quantizing magnetic fields
Nicolas Chamel · Zhivko Krastev Stoyanov
The iterative method recently proposed for determining the internal constitution of the outer crust of a nonaccreted neutron star is extended to magnetars by taking into account the Landau-Rabi quantization of electron motion induced by the presence of a very high magnetic field. It is shown that in the strongly quantizing regime, the method can be efficiently implemented using new analytical solutions for the transitions between adjacent crustal layers. Detailed numerical computations are performed to assess the performance and precision of the method.
↳ astro-ph.HEnucl-thPRC(2020)·9 citations
10
Characterizing Proton-Proton Collisions at the Large Hadron Collider with Thermal Properties
Dushmanta Sahu🇮🇳 · Raghunath Sahoo🇮🇳
High-multiplicity proton-proton (pp) collisions at the Large Hadron Collider (LHC) energies have created a new domain of research to look for a possible formation of quark-gluon plasma in these events. In this paper, we estimate various thermal properties of the matter formed in pp collisions at the LHC energies, such as mean free path, isobaric expansivity, thermal pressure, and heat capacity using a thermodynamically consistent Tsallis distribution function. Particle species-dependent mean free path and isobaric expansivity are studied as functions of final state charged particle multiplicity for pp collisions at the center-of-mass energy $s$ = 7 TeV. The effects of degree of non-extensivity, baryochemical potential, and temperature on these thermal properties are studied. The findings are compared with the theoretical expectations.
↳ hep-phhep-exnucl-exnucl-thMDPI Physics(2021)·8 citations

Affiliations

first authorsco-authorsvia INSPIRE