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Nuclear Theory·nucl-th

Wednesday·July 31, 2019

9 papers—3 primary·6 cross-listed

All9Primary3Cross-lists6
  1. 04

    LIght scalars with lepton number to solve the anomaly

    Susan Gardner🇺🇸 · Xinshuai Yan🇺🇸

    Scalars that carry lepton number can help mediate would-be lepton-number-violating processes, such as neutrinoless double decay or lepton-scattering-mediated nucleon-antinucleon conversion. Here we show that such new scalars can also solve the anomaly in precision determinations of the fine-structure constant from atom interferometry and from the electron's anomalous magnetic moment, , by reducing . Study of the phenomenological constraints on these solutions favor a doubly-charged scalar with mass below the GeV scale. Significant constraints arise from the measurement of the parity-violating asymmetry in Møller scattering, and we consider the implications of the next-generation MOLLER experiment at Jefferson Laboratory and of an improved measurement.

    ↳ hep-phnucl-thphysics.atom-phPRD(2020)·23 citations
  2. 05

    Nonlinear causality of general first-order relativistic viscous hydrodynamics

    Fábio S. Bemfica (Rio Grande do Norte U.) · Marcelo M. Disconzi (Vanderbilt U.) · Jorge Noronha (Illinois U., Urbana)

    Effective theory arguments are used to derive the most general energy-momentum tensor of a relativistic viscous fluid with an arbitrary equation of state (in the absence of other conserved currents) that is first-order in the derivatives of the energy density and flow velocity and does not include extended variables such as in Mueller-Israel-Stewart-like theories. This energy-momentum tensor leads to a causal theory, provided one abandons the usual conventions for the out-of-equilibrium hydrodynamic variables put forward by Landau-Lifshitz and Eckart. In particular, causality requires nonzero out-of-equilibrium energy density corrections and heat flow. Conditions are found to ensure linear stability around equilibrium in flat space-time. We also prove local existence and uniqueness of solutions to the equations of motion. Our causality, existence, and uniqueness results hold in the full nonlinear regime, without symmetry assumptions, in four space-time dimensions, with or without coupling to Einstein's equations, and are mathematically rigorously established. Furthermore, a kinetic theory realization of this energy-momentum tensor is also provided.

    ↳ gr-qchep-thnucl-thPRD(2019)·238 citations
  3. 06

    Chirality of Nd reexamined: Evidence for multiple chiral doublet bands

    B.F. Lv🇫🇷 · C. M. Petrache🇫🇷 · Q. B. Chen🇩🇪 · J. Meng🇨🇳 · A. Astier🇫🇷 · E. Dupont🇫🇷 · P. Greenlees🇫🇮 · H. Badran🇫🇮 · T. Calverley🇫🇮 · D. M. Cox🇫🇮 · T. Grahn🇫🇮 · J. Hilton🇫🇮 and 26 other authors

    One new pair of positive-parity chiral doublet bands have been identified in the odd- nucleus Nd which together with the previously reported negative-parity chiral doublet bands constitute a third case of multiple chiral doublet (MD) bands in the mass region. The properties of the MD bands are well reproduced by constrained covariant density functional theory and particle rotor model calculations. The newly observed MD bands in Nd represents an important milestone in supporting the existence of MD in nuclei.

    ↳ nucl-exnucl-thPRC(2019)·32 citations
  4. 07

    Dipole evolution: perspectives for collectivity and A collisions

    Christian Bierlich🇸🇪 · Christine O. Rasmussen🇸🇪

    The transverse, spatial structure of protons is an area revealing fundamental properties of matter, and provides key input for deeper understanding of emerging collective phenomena in high energy collisions of protons, as well as collisions of heavy ions. In this paper eccentricities and eccentricity fluctuations are predicted using the dipole formulation of BFKL evolution. Furthermore, first steps are taken towards generation of fully exclusive final states of A collisions, by assessing the importance of colour fluctuations in the initial state. Such steps are crucial for the preparation of event generators for a future electron-ion collider. Due to the connection between an impact parameter picture of the proton structure, and cross sections of ep and pp collisions, the model parameters can be fully determined by fits to such quantities, leaving results as real predictions of the model.

    ↳ hep-phnucl-thJHEP(2019)·22 citations
  5. 08

    Time Evolution Operators for Periodic SU(3)

    P. G. Morrison

    We present an outline of a technique to associate certain methods from time optimal quantum control with various transforms on SU(3). Unitary operators are taken from certain time dependent Hamiltonians and transformation laws are derived. A methodological framework for development of solution for these types of problems with a non-simple geometric framework is presented that is generally applicable. We give an expansive overview of the field of SU(3), its meaning, purpose and context within the presented results. Exact solutions for periodic curves on SU(3) are provided, along with the operators and physical framework that surrounds them. A comprehensive review of the literature and established results is given for reference. Discussion is given in full to effective approaches that may be given both to the teaching of the subject, and the development of further results within the science. We conclude the paper with an overview of new avenues of investigation that are opened through the results that are presented.

    ↳ quant-phnucl-th2 citations
  6. 09

    Acceleration of the Sn Equations with Highly Anisotropic Scattering using the Fokker-Planck Equation

    Japan K. Patel · James S. Warsa · Anil K. Prinja

    The discrete ordinates method can model forward-peaked transport problems accurately. However, convergence of discrete ordinates solution can become arbitrarily slow upon use of standard iterative procedures like source iteration and GMRES. Standard zeroth and first moment-based acceleration methods like nonlinear diffusion acceleration and diffusion synthetic acceleration are ineffective in accelerating such problems because these methods do not correct higher order Legendre-moments of angular flux. We explore the idea of using Fokker-Planck as a preconditioner to accelerate forward-peaked transport problems in this paper.

    ↳ physics.comp-phnucl-th1 citation

Affiliations

first authorsco-authorsvia INSPIRE