Nuclear Theory·nucl-th

Thursday·January 17, 2019

9 papers—4 primary·5 cross-listed

01
Isoscalar pairing interaction for the quasiparticle random-phase approximation approach to double- $β$ and $β$ decays
J. Terasaki🇨🇿 · Y. Iwata🇯🇵
We have proposed in a series of previous papers a method to determine the effective axial-vector current coupling and the strength of the isoscalar proton-neutron pairing interaction for calculating the nuclear matrix elements of the neutrinoless double- $β$ decay by the quasiparticle random-phase approximation. The combination of these two parameters have had an uncertainty in this approach, but now this uncertainty is removed. In this paper, we apply our method to the neutrinoless double- $β$ decays of $^{136}$ Xe and $^{130}$ Te and predict the nuclear matrix elements and reduced half-lives. Our calculation is tested first by a self-check method using the two-neutrino double- $β$ decay, and this test ensures the application of our method to $^{136}$ Xe. It turns out, however, that our method is not successful in $^{130}$ Te. Further test is made for our calculation of the $β$ decay of $^{138}$ Xe, and a satisfactory result is obtained.
nucl-thhep-exnucl-exPRC(2019)·18 citations
02
Neutron gas and pairing
M. Anguiano🇪🇸 · A. M. Lallena🇪🇸 · R. Bernard🇫🇷 · G. Co'🇮🇹
We study the emergence of neutron gas effects in the description of nuclei with large neutron excess within the Bardeen-Cooper-Schrieffer approach. We consider Ni and Sn isotopes where, in the literature, these effects have been found. We investigate the role of the single particle states with positive energy generating the neutron gas, and we find that the contribution of these states is numerically irrelevant for the various observables that we evaluate.
nucl-thPRC(2019)·5 citations
03
Thermal-FIST: A package for heavy-ion collisions and hadronic equation of state
Volodymyr Vovchenko🇩🇪 · Horst Stoecker🇩🇪
Thermal-FIST (Thermal, Fast and Interactive Statistical Toolkit) is a C++ package designed for a convenient general-purpose physics analysis within the family of hadron resonance gas (HRG) models. This mainly includes the statistical analysis of particle production in heavy-ion collisions and the phenomenology of hadronic equation of state. Notable features include fluctuations and correlations of conserved charges, effects of probabilistic decay, chemical non-equilibrium, and inclusion of van der Waals hadronic interactions. Calculations are possible within the grand canonical ensemble, the canonical ensemble, as well as in mixed-canonical ensembles combining the canonical treatment of certain conserved charges with the grand-canonical treatment of other conserved charges. The package contains a fast thermal event generator, which generates particle yields in accordance with the HRG chemistry, and particle momenta based on the Blast Wave model. A distinct feature of this package is the presence of the graphical user interface frontend -- QtThermalFIST -- which is designed for fast and convenient general-purpose HRG model applications.
nucl-thhep-phnucl-exComput.Phys.Commun.(2019)·221 citations
04
Direct flow of heavy mesons as unique probe of the initial Electro-Magnetic fields in Ultra-Relativistic Heavy Ion collisions
Gabriele Coci🇮🇹 · Lucia Oliva🇮🇹 · Salvatore Plumari🇮🇹 · Santosh Kumar Das🇮🇹 · Vincenzo Greco🇮🇹
In Ultra-relativistic Heavy-Ion Collisions (HICs) very strong initial electro-magnetic (E.M.) fields are created: the order of magnitude of the magnetic field is about $1 0^{19} G a u ss$ , the most intense field in the Universe, even larger than that of a magnetar. These fields rapidly decrease in time, inducing a drift of particles in the reaction plane. The resulting flow is odd under charge exchange and this allows to distinguish it from the large vorticity of the bulk matter due to the initial angular momentum conservation. Conjointly charm quarks, thanks to their large mass $M_{c} >> Λ_{QC D}$ , are produced in hard partonic processes at formation time $τ_{f} \approx 1 / (2 M_{H Q})$ which is comparable with the time scale when the E.M. field attains its maximum value. Moreover, with a mass of $M_{c} \approx 1.3$ GeV there should be no mixing with the chiral magnetic dynamics and the condition $M_{c} ≫ T$ allows charm quarks to have sufficiently large thermalization time, so that they can probe the entire phase-space evolution of the QGP retaining the initial kick given by the E.M. field. We show that such E.M. field entails a transverse motion of charm quarks resulting in a splitting of directed flow $v_{1}$ of $D$ and $D ˉ$ mesons of few percent, i.e. much larger compared to the measured pion one.
nucl-thNPA(2019)·11 citations
05
Physics Beyond Colliders: QCD Working Group Report
A. Dainese🇮🇹 · M. Diehl🇩🇪 · P. Di Nezza🇮🇹 · J. Friedrich🇩🇪 · M. Gaździcki🇩🇪 · G. Graziani🇮🇹 · C. Hadjidakis🇫🇷 · J. Jäckel🇩🇪 · J. P. Lansberg🇫🇷 · A. Magnon🇨🇭 · G. Mallot🇨🇭 · F. Martinez Vidal🇪🇸 and 11 other authors
This report summarises the main findings of the QCD Working Group in the CERN Physics Beyond Colliders Study.
↳ hep-exhep-phnucl-exnucl-th26 citations
06
nEoS: Neutron Star Equation of State from hadron physics alone
Eva Lope Oter🇪🇸 · Andreas Windisch🇺🇸 · Felipe J. Llanes-Estrada🇪🇸 · Mark Alford🇺🇸
We contribute a publicly available set of tables and code to provide Equations of State (EoS) for matter at neutron star densities. Our EoSes are constrained only by input from hadron physics and fundamental principles, without feedback from neutron star observations, and so without relying on General Relativity. They can therefore be used to test General Relativity itself, as well as modified gravity theories, with neutron star observables, without logical circularity. We have adapted state of the art results from NN chiral potentials for the low--density limit, pQCD results for the asymptotically high-density EoS, and use monotonicity and causality as the only restrictions for intermediate densities, for the EoS sets to remain as model-independent as is feasible today.
↳ gr-qcastro-ph.HEhep-phnucl-thJ.Phys.G(2019)·36 citations
07
Van Hove Singularities and Excited-State Quantum Phase Transitions in Graphene-like Microwave Billiards
Michal Macek · Barbara Dietz
We discuss solutions of an algebraic model of the hexagonal lattice vibrations, which point out interesting localization properties of the eigenstates at van Hove singularities (vHs), whose energies correspond to Excited-State Quantum Phase Transitions (ESQPT). We show that these states form stripes oriented parallel to the zig-zag direction of the lattice, similar to the well-known edge states found at the Dirac point, however the vHs-stripes appear in the bulk. We interpret the states as lines of cell-tilting vibrations, and inspect their stability in the large lattice-size limit. The model can be experimentally realized by superconducting 2D microwave resonators containing triangular lattices of metallic cylinders, which simulate finite-sized graphene flakes. Thus we can assume that the effects discussed here could be experimentally observed.
↳ cond-mat.mes-hallcond-mat.othernucl-thAIP Conf.Proc.(2019)·1 citation
08
Nuclear configurational entropy of the energy-energy correlation in $e^{+} e^{-}$ annihilation processes
G. Karapetyan🇧🇷
In this paper the nuclear configurational entropy of the energy--energy correlation function is scrutinized, in $e^{+} e^{-}$ collisions to hadrons in the back-to-back region, within the QCD perturbative theory. The critical points of the nuclear configurational entropy concept, in the hot nuclear system, is shown to correspond to the critical angle between the two scattered hadrons, corroborating with phenomenological data with great accuracy. The main tools employ the main coefficients of the soft-gluon resummation formula, taking into account logarithmically enhanced contributions up to next-to-next-to-leading logarithmic accuracy.
↳ hep-phnucl-thEPL(2019)·24 citations
09
Reconstructing parton distribution functions from Ioffe time data: from Bayesian methods to Neural Networks
Joseph Karpie🇺🇸 · Kostas Orginos🇺🇸 · Alexander Rothkopf · Savvas Zafeiropoulos🇩🇪
The computation of the parton distribution functions (PDF) or distribution amplitudes (DA) of hadrons from first principles lattice QCD constitutes a central open problem. In this study, we present and evaluate the efficiency of a selection of methods for inverse problems to reconstruct the full $x$ -dependence of PDFs. Our starting point are the so called Ioffe time PDFs, which are accessible from Euclidean time calculations in conjunction with a matching procedure. Using realistic mock data tests, we find that the ill-posed incomplete Fourier transform underlying the reconstruction requires careful regularization, for which both the Bayesian approach as well as neural networks are efficient and flexible choices.
↳ hep-lathep-phnucl-thJHEP(2019)·152 citations

Affiliations

first authorsco-authorsvia INSPIRE