PaperPanorama
FAQ

Nuclear Theory·nucl-th

Tuesday·January 4, 2022

9 papers—6 primary·3 cross-listed

All9Primary6Cross-lists3
  1. 01

    Influence of moments of inertia on transverse wobbling mode in odd-mass nuclei

    Hui Zhang · Bin Qi · Xu Dong Wang · Hui Jia · Shou Yu Wang

    The reported transverse wobbling band in odd-mass Pd has been reinvestigated by the triaxial particle rotor model. Employing different parameter sets of moment of inertia (MOI), several calculated results could be in good agreement with the experimental data, which show distinct modes of rotational excitation, respectively. These modes are sensitive to the ratio between the MOI at intermediate and short axis. With the increase of this ratio, a wobble about the short axis of the total angular momentum is gradually changed to a wobble about the intermediate axis. In addition, it is exhibited that precession and tunneling are two aspects of the quantum wobbling motion. The tunneling aspect dominates in the yrare states of Pd. The present results in Pd show the complexity of the transverse wobbling mode.

    nucl-thPRC(2022)·14 citations
  2. 02

    Direct Nuclear Reactions

    Carlos A. Bertulani · Angela Bonaccorso

    In this brief review we discuss the basic theoretical concepts used in the experimental studies of the most common cases of direct reactions such as (a) elastic scattering, (b) inelastic scattering, (c) Coulomb excitation, (d) transfer reactions and (e) breakup reactions.

    nucl-thnucl-ex0 citations
  3. 03

    Quark-nuclear hybrid equation of state for neutron stars under modern observational constraints

    G.A. Contrera🇦🇷 · D. Blaschke🇵🇱 · J.P. Carlomagno🇦🇷 · A.G. Grunfeld🇦🇷 · S. Liebing🇷🇺

    We study a family of equations of state for hybrid neutron star matter. The hybrid EOS are obtained by a Maxwell construction of the first-order phase transition between a hadronic phase described by the relativistic density-functional EOS of the "DD2" class with excluded volume effects and a deconfined quark matter phase modeled by an instantaneous nonlocal version of the Nambu-Jona-Lasinio model in SU(2) with vector interactions and color superconductivity. The form factor in the nonlocal quark matter model is fitted to lattice QCD results in the Coulomb gauge. Owing to strong coupling in the vector meson and diquark channels, a coexistence phase of color superconductivity and chiral symmetry breaking occurs. Our results show an approximately constant behavior for the squared speed of sound with values of 0.4 - 0.6 in the density region relevant for neutron star interiors. To simultaneously fulfill the constraints from the Neutron Star Interior Composition Explorer radius measurement for PSR J0740+6620 and tidal deformability from GW170817 it is necessary to consider a -dependent bag pressure that mimics confinement.

    nucl-thastro-ph.HEPRC(2022)·69 citations
  4. 04

    Bootstrapping the deuteron

    Dong Bai🇨🇳

    Bootstrap is a novel and ambitious paradigm for quantum physics. It aims to solve the target problems by exploiting theoretical constraints from general physical principles and self-consistency conditions. The bootstrap philosophy dates back to the 1960s. Its real power has been recognized only recently in, e.g., conformal field theories and relativistic scattering amplitudes. Inspired by [X. Han, S. A. Hartnoll, and J. Kruthoff, Phys. Rev. Lett. 125, 041601 (2020)], we report the first bootstrap results in low-energy nuclear physics, where deuteron, with its Hamiltonian given by pionless effective field theory in harmonic oscillator space, is solved by directly exploiting the most fundamental quantum mechanical requirement that probability should never be negative. Our study shows that the bootstrap method can be helpful in studying realistic nuclear systems.

    nucl-thhep-th16 citations
  5. 05

    Nuclear masses learned from a probabilistic neural network

    A.E. Lovell · A.T. Mohan · T.M. Sprouse · M.R. Mumpower

    Machine learning methods and uncertainty quantification have been gaining interest throughout the last several years in low-energy nuclear physics. In particular, Gaussian processes and Bayesian Neural Networks have increasingly been applied to improve mass model predictions while providing well-quantified uncertainties. In this work, we use the probabilistic Mixture Density Network (MDN) to directly predict the mass excess of the 2016 Atomic Mass Evaluation within the range of measured data, and we extrapolate the inferred models beyond available experimental data. The MDN not only provides mean values but also full posterior distributions both within the training set and extrapolated testing set. We show that the addition of physical information to the feature space increases the accuracy of the match to the training data as well as provides for more physically meaningful extrapolations beyond the the limits of experimental data.

    nucl-thnucl-exPRC(2022)·60 citations
  6. 06

    Simultaneous description of wobbling and chiral properties in even-odd triaxial nuclei

    C. M. Raduta · A. A. Raduta · R. Poenaru · Al.H. Raduta

    A particle-triaxial rigid core Hamiltonian is semi-classically treated. The coupling term corresponds to a particle rigidly coupled to the triaxial core, along a direction that does not belong to any principal plane of the inertia ellipsoid.The equations of motion for the angular momentum components provide a sixth-order algebraic equation for one component and subsequently equations for the other two. Linearizing the equations of motion, a dispersion equation for the wobbling frequency is obtained. The equations of motion are also considered in the reduced space of generalized phase space coordinates. Choosing successively the three axes as quantization axis will lead to analytical solutions for the wobbling frequency, respectively. The same analysis is performed for the chirally transformed Hamiltonian. With an illustrative example one identified wobbling states whose frequencies are mirror image to one another. Changing the total angular momentum I, a pair of twin bands emerged. Note that the present formalism conciliates between the two signatures of triaxial nuclei, i.e., they could coexist for a single nucleus.

    nucl-thJ.Phys.G(2022)·7 citations
  7. 07

    Possible early universe signals in proton collisions at the Large Hadron Collider

    Raghunath Sahoo🇮🇳 · Tapan Kumar Nayak🇨🇭

    Our universe was born about 13.8 billion years ago from an extremely hot and dense singular point, in a process known as the Big Bang. The hot and dense matter which dominated the system within a few microseconds of its birth was in the form of a soup of elementary quarks and gluons, known as the quark-gluon plasma (QGP). Signatures compatible with the formation of the QGP matter have experimentally been observed in heavy-ion (such as Au or Pb) collisions at ultra-relativistic energies. Recently, experimental data of proton-proton (pp) collisions at the CERN Large Hadron Collider (LHC) have also shown signals resembling those of the QGP formation, which made these studies quite stimulating as to how the collision of small systems features in producing the early universe signals. In this article, we report on some of the compelling experimental results and give an account of the present understanding. We review the pp physics program at the LHC and discuss future prospects in the context of exploring the nature of the primordial matter in the early universe.

    ↳ hep-phhep-exhep-thnucl-ex+1Curr.Sci.(2021)·22 citations
  9. 09

    Analysis on the composite nature of the light scalar mesons and

    Ze-Qiang Wang🇨🇳 · Xian-Wei Kang🇨🇳 · J. A. Oller🇪🇸 · Lu Zhang🇨🇳

    We study the weight or compositeness of the - and - in the composition of the and resonances, respectively. Either we use the saturation of the total width and compositeness, or we use a Flatté parameterization taking also into account the spectral function of a near-threshold resonance. We make connections and compare between these two methods. We take input values for the pole mass and width from several determinations in the literature. In addition, we take as third input either the total compositeness or the decay-width branching ratio to the lighter channel for each resonance. It turns out that for the poles considered the meson-meson components are dominant for the , while for the resonance they are subdominant. We also provide partial decay widths and partial compositeness coefficients, so that the component is the most important one for the . Additionally, this study stresses the need to distinguish between the bare and dressed couplings and widths in a Flatté parameterization. We elaborate on the connection between the partial-decay widths calculated in terms of the dressed couplings and the actual measured ones. Due to the coupled-channel dynamics when the pole lies near the heavier threshold in the second Riemann sheet some changes are needed with respect to standard relations.

    ↳ hep-phhep-exnucl-thPRD(2022)·29 citations

Affiliations

first authorsco-authorsvia INSPIRE