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Nuclear Theory·nucl-th

Wednesday·October 13, 2021

10 papers—5 primary·5 cross-listed

All10Primary5Cross-lists5
  1. 06

    Chiral extrapolation of hadronic vacuum polarization

    Gilberto Colangelo🇨🇭 · Martin Hoferichter🇨🇭 · Bastian Kubis🇩🇪 · Malwin Niehus🇩🇪 · Jacobo Ruiz de Elvira🇨🇭

    We study the pion-mass dependence of the two-pion channel in the hadronic-vacuum-polarization (HVP) contribution to the anomalous magnetic moment of the muon , by using an Omnès representation for the pion vector form factor with the phase shift derived from the inverse-amplitude method (IAM). Our results constrain the dominant isospin- part of the isospin-symmetric light-quark contribution, and should thus allow one to better control the chiral extrapolation of , required for lattice-QCD calculations performed at larger-than-physical pion masses. In particular, the comparison of the one- and two-loop IAM allows us to estimate the associated systematic uncertainties and show that these are under good control.

    ↳ hep-phhep-latnucl-thPLB(2022)·41 citations
  2. 07

    Effect of the Nuclear Equation of State on Relativistic-Turbulence Induced Core-Collapse Supernovae

    Luca Boccioli · Grant J. Mathews · In-Saeng Suh · Evan P. O'Connor

    The nuclear equation of state is an important component in the evolution of core collapse supernovae. In this paper we make a survey of various equations of state in the literature and analyze their effect on spherical core-collapse models in which the effects of three-dimensional turbulence is modeled by a general relativistic formulation of Supernova Turbulence in Reduced dimensionality (STIR). We show that the viability of the explosion is quite EOS dependent and that it best correlates with the early-time interior entropy density of the proto-neutron star. We check that this result is not progenitor dependent, although low-mass progenitors show different explosion properties, due to the different pre-collapse nuclear composition. Larger central entropies also induce more vigorous proto-neutron-star convection in our one-dimensional turbulence model, as well as a wider convective layer.

    ↳ astro-ph.HEnucl-thApJ(2022)·34 citations
  3. 08

    Extending Israel and Stewart hydrodynamics to relativistic superfluids via Carter's multifluid approach

    Lorenzo Gavassino🇵🇱 · Marco Antonelli🇵🇱 · Brynmor Haskell🇵🇱

    We construct a relativistic model for bulk viscosity and heat conduction in a superfluid. Building on the principles of Unified Extended Irreversible Thermodynamics, the model is derived from Carter's multifluid approach for a theory with 3 four-currents: particles, entropy, and quasi-particles. Dissipation arises directly from the fact that the quasi-particle four-current is an independent degree of freedom that does not necessarily comove with the entropy. For small deviations from local thermodynamic equilibrium, the model provides an extension of the Israel-Stewart theory to superfluid systems. It can, therefore, be made hyperbolic, causal and stable if the microscopic input is accurate. The non-dissipative limit of the model is the relativistic two-fluid model of Carter, Khalatnikov and Gusakov. The Newtonian limit of the model is an Extended-Irreversible-Thermodynamic extension of Landau's two-fluid model. The model predicts the existence of four bulk viscosity coefficients and accounts for their microscopic origin, providing their exact formulas in terms of the quasi-particle creation rate. Furthermore, when fast oscillations of small amplitude around the equilibrium are considered, the relaxation-time term in the telegraph-type equations for the bulk viscosities accounts directly for their expected dependence on the frequency.

    ↳ gr-qcastro-ph.HEnucl-thphysics.flu-dynPRD(2022)·17 citations
  4. 09

    Pion GPDs: A path toward phenomenology

    José Manuel Morgado Chavez🇪🇸 · Valerio Bertone🇫🇷 · Feliciano De Soto Borrero🇪🇸 · Maxime Defurne🇫🇷 · Cédric Mezrag🇫🇷 · Hervé Moutarde🇫🇷 · José Rodríguez-Quintero🇪🇸 · Jorge Segovia🇪🇸

    We introduce a new family of Generalised Parton Distribution models able to fulfil by construction all the theoretical properties imposed by QCD. These models are built on standard Parton Distribution Functions and extended to off-forward kinematics through a well-defined procedure. We apply this strategy on the pion, first handling a simple but insightful algebraic model, and then exploiting state-of-the-art computations obtained in continuum QCD. We compare these models with a more standard one relying on an xFitter extraction of the pion Parton Distribution Functions. The results for both quark and gluon Generalised Parton Distributions are presented and exploited for calculation of Electromagnetic, Gravitational and Compton Form Factors. Results on the latter highlight the relevance of next-to-leading order corrections, even in the so-called valence region.

    ↳ hep-phnucl-thPRD(2022)·59 citations
  5. 10

    X17 discovery potential in the process at electron scattering facilities

    Johannes Backens🇩🇪 · Marc Vanderhaeghen🇩🇪

    We propose a direct search for the X17 particle, which was conjectured to explain the ATOMKI Be and He anomalies, through the dilepton photoproduction process on a nucleon in the photon energy range below or around the pion production threshold. For the scenarios of either pseudoscalar, vector, or axial-vector quantum numbers of the conjectured X17, we use existing constraints to estimate the X17 signal process. For dilepton resolutions which have been achieved in previous experiments, a signal-to-background ratio of up to an order of magnitude is found for a neutron target, and in particular for the pseudoscalar and vector X17 scenarios.

    ↳ hep-phnucl-thPRL(2022)·12 citations

Affiliations

first authorsco-authorsvia INSPIRE