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Nuclear Theory·nucl-th

Monday·December 16, 2019

4 papers—1 primary·3 cross-listed

All4Primary1Cross-lists3
  1. 02

    Lepton-Nucleus Cross Section Measurements for DUNE with the LDMX Detector

    Artur M. Ankowski🇺🇸 · Alexander Friedland🇺🇸 · Shirley Weishi Li🇺🇸 · Omar Moreno🇺🇸 · Philip Schuster🇺🇸 · Natalia Toro🇺🇸 · Nhan Tran🇺🇸

    We point out that the LDMX (Light Dark Matter eXperiment) detector design, conceived to search for sub-GeV dark matter, will also have very advantageous characteristics to pursue electron-nucleus scattering measurements of direct relevance to the neutrino program at DUNE and elsewhere. These characteristics include a 4-GeV electron beam, a precision tracker, electromagnetic and hadronic calorimeters with near 2 azimuthal acceptance from the forward beam axis out to 40 angle, and low reconstruction energy threshold. LDMX thus could provide (semi)exclusive cross section measurements, with detailed information about final-state electrons, pions, protons, and neutrons. We compare the predictions of two widely used neutrino generators (GENIE, GiBUU) in the LDMX region of acceptance to illustrate the large modeling discrepancies in electron-nucleus interactions at DUNE-like kinematics. We argue that discriminating between these predictions is well within the capabilities of the LDMX detector.

    ↳ hep-phhep-exnucl-exnucl-thPRD(2020)·31 citations
  2. 03

    Hierarchical Bayesian Thermonuclear Rate for the Be(n,p)Li Big Bang Nucleosynthesis Reaction

    Rafael S. de Souza🇺🇸 · Tan Hong Kiat🇸🇬 · Alain Coc🇫🇷 · Christian Iliadis🇺🇸

    Big bang nucleosynthesis provides the earliest probe of standard model physics, at a time when the universe was less than a thousand seconds old. It determines the abundances of the lightest nuclides, which give rise to the subsequent history of the visible matter in the Universe. This work derives new Be(n,p)Li thermonuclear reaction rates based on all available experimental information. This reaction sensitively impacts the primordial abundances of Be and Li during big bang nucleosynthesis. We critically evaluate all available data and disregard experimental results that are questionable. For the nuclear model, we adopt an incoherent sum of single-level, two-channel R-matrix approximation expressions, which are implemented into a hierarchical Bayesian model, to analyze the remaining six data sets we deem most reliable. In the fitting of the data, we consistently model all known sources of uncertainty, including discrepant absolute normalizations of different data sets, and also take the variation of the neutron and proton channel radii into account, hence providing less biased estimates of the Be(n,p)Li thermonuclear rates. From the resulting posteriors, we extract R-matrix parameters (, , ) and derive excitation energies, partial and total widths. Our fit is sensitive to the contributions of the first three levels above the neutron threshold. Reaction rates were computed by integrating 10,000 samples of the reduced cross section. Our Be(n,p)Li thermonuclear rates have uncertainties between 1.5% and 2.0% at temperatures of 1 GK. We compare our rates to previous results and find that the Be(n,p)Li rates most commonly used in big bang simulations have too optimistic uncertainties.

    ↳ astro-ph.COastro-ph.IMnucl-thApJ(2020)·17 citations
  3. 04

    The physics of helical electron beam in a uniform magnetic field as a testing ground of gauge principle

    M. Wakamatsu · Y. Kitadono · L.-P. Zou · P.-M. Zhang

    According to Bliokh et al., allowing free propagation along the direction of a uniform magnetic field, the familiar Landau electron state can be regarded as a non-diffracting version of the helical electron beam propagating along the magnetic field. Based on this observation, they argued that, while propagating along the magnetic field, the Landau electrons receive characteristic rotation with three different angular velocities, depending on the eigen-value of the canonical OAM operator, which is generally gauge-variant, and this splitting was in fact experimentally confirmed. Through complete analyses of highly mysterious -dependent rotational dynamics of the quantum Landau states, we try to make clear how and why their observation does not contradict the widely-believed gauge principle.

    ↳ quant-phnucl-thphysics.opticsPLA(2020)·14 citations

Affiliations

first authorsco-authorsvia INSPIRE