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Nuclear Theory·nucl-th

Wednesday·August 9, 2023

4 papers—1 primary·3 cross-listed

All4Primary1Cross-lists3
  1. 02

    [Submitted on 7 Aug 2023] (cross-list from quant-ph)

    Liouvillian Dynamics of the Open Schwinger Model: String Breaking and Kinetic Dissipation in a Thermal Medium

    Kyle Lee🇺🇸 · James Mulligan🇺🇸 · Felix Ringer🇺🇸 · Xiaojun Yao🇺🇸

    Understanding the dynamics of bound state formation is one of the fundamental questions in confining quantum field theories such as Quantum Chromodynamics (QCD). One hadronization mechanism that has garnered significant attention is the breaking of a string initially connecting a fermion and an anti-fermion. Deepening our understanding of real-time string-breaking dynamics with simpler, lower dimensional models like the Schwinger model can improve our understanding of the hadronization process in QCD and other confining systems found in condensed matter and statistical systems. In this paper, we consider the string-breaking dynamics within the Schwinger model and investigate its modification inside a thermal medium, treating the Schwinger model as an open quantum system coupled to a thermal environment. Within the regime of weak coupling between the system and environment, the real-time evolution of the system can be described by a Lindblad evolution equation. We analyze the Liouvillian gaps of this Lindblad equation and the time dependence of the system's von Neumann entropy. We observe that the late-time relaxation rate decreases as the environment correlation length increases. Moreover, when the environment correlation length is infinite, the system exhibits two steady states, one in each of the sectors with definite charge-conjugation-parity (CP) quantum numbers. For parameter regimes where an initial string breaks in vacuum, we observe a delay of the string breaking in the medium, due to kinetic dissipation effects. Conversely, in regimes where an initial string remains intact in vacuum time evolution, we observe string breaking (melting) in the thermal medium. We further discuss how the Liouvillian dynamics of the open Schwinger model can be simulated on quantum computers and provide an estimate of the associated Trotter errors.

    Comments:
    24 pages, 16 figures; v2: added an appendix to explain the dependence of Liouvillian gaps on environment correlation functions and system sizes; v3: add references; v4,v5: correct typos
    Subjects:
    Quantum Physics (quant-ph); High Energy Physics — Lattice (hep-lat); High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
    arXiv:
    2308.03878 [pdf]
    PRD(2023)·38 citations
  2. 03

    [Submitted on 8 Aug 2023] (cross-list from astro-ph.HE)

    Neutrinos and nucleosynthesis of elements

    Tobias Fischer🇵🇱 · Gang Guo🇨🇳 · Karlheinz Langanke🇩🇪 · Gabriel Martinez-Pinedo🇩🇪 · Yong-Zhong Qian🇺🇸 · Meng-Ru Wu🇹🇼

    Neutrinos are known to play important roles in many astrophysical scenarios from the early period of the big bang to current stellar evolution being a unique messenger of the fusion reactions occurring in the center of our sun. In particular, neutrinos are crucial in determining the dynamics and the composition evolution in explosive events such as core-collapse supernovae and the merger of two neutron stars. In this paper, we review the current understanding of supernovae and binary neutron star mergers by focusing on the role of neutrinos therein. Several recent improvements on the theoretical modeling of neutrino interaction rates in nuclear matter as well as their impact on the heavy element nucleosynthesis in the supernova neutrino-driven wind are discussed, including the neutrino-nucleon opacity at the mean field level taking into account the relativistic kinematics of nucleons, the effect due to the nucleon-nucleon correlation, and the nucleon-nucleon bremsstrahlung. We also review the framework used to compute the neutrino-nucleus interactions and the up-to-date yield prediction for isotopes from neutrino nucleosynthesis occurring in the outer envelope of the supernova progenitor star during the explosion. Here improved predictions of energy spectra of supernova neutrinos of all flavors have had significant impact on the nucleosynthesis yields. Rapid progresses in modeling the flavor oscillations of neutrinos in these environments, including several novel mechanisms for collective neutrino oscillations and their potential impacts on various nucleosynthesis processes are summarized.

    Comments:
    Matches the published version on PPNP
    Subjects:
    High Energy Astrophysical Phenomena (astro-ph.HE); Solar and Stellar Astrophysics (astro-ph.SR); High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
    arXiv:
    2308.03962 [pdf]
    PPNP(2024)·68 citations
  3. 04

    [Submitted on 8 Aug 2023] (cross-list from hep-ph)

    Puzzles in the hadronic contributions to the muon anomalous magnetic moment

    Gilberto Colangelo🇨🇭 · Martin Hoferichter🇨🇭 · Peter Stoffer🇨🇭

    We summarize recent developments in the Standard-Model evaluation of the anomalous magnetic moment of the muon , both in the hadronic-light-by-light and hadronic-vacuum-polarization contributions. The current situation for the latter is puzzling as we are confronted with multiple discrepancies that are not yet understood. We present updated fits of a dispersive representation of the pion vector form factor to the new CMD-3 data set and quantify the tensions with the other high-statistics experiments in the contribution to in the energy range up to 1 GeV, as well as in the corresponding contribution to the intermediate Euclidean window.

    Comments:
    12 pages, 1 figure, proceedings for "21st Conference on Flavor Physics and CP Violation," "Les Rencontres de Physique de la Vallée d'Aoste," and "New Frontiers in Lepton Flavor"
    Subjects:
    High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Experiment (hep-ex); High Energy Physics — Lattice (hep-lat); Nuclear Theory (nucl-th)
    arXiv:
    2308.04217 [pdf]
    JINST(2023)·46 citations

Affiliations

first authorsco-authorsvia INSPIRE