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#quantumfieldtheory — Public Fediverse posts

Live and recent posts from across the Fediverse tagged #quantumfieldtheory, aggregated by home.social.

  1. АНТРОПОЛОГИЯ, ANTHROPOLOGY, АНТРОПОЛОГІЯ
    #АНТРОПОЛОГИЯ, #ANTHROPOLOGY, #АНТРОПОЛОГІЯ
    t.me/scilib_yura15cbx/542

    Thermodynamics, statistical physics
    Термодинамика, статистическая физика
    Термодинаміка, статистична фізика
    #Thermodynamics, #statistical physics
    #Термодинамика, #статистическаяфизика
    #Термодинаміка, #статистична
    фізика
    t.me/scilib_yura15cbx/541

    PQm Quantum mechanics
    Квантовая механика
    Квантова механіка
    #Quantum mechanics
    #Квантоваямеханика
    #Квантова
    механіка
    t.me/scilib_yura15cbx/540

    PQft Quantum field theory
    Квантовая теория поля
    Квантова теорія поля
    #Quantum field theory
    t.me/scilib_yura15cbx/539

    Фазовые переходы
    Phase_transitions, Фазовіпереходи
    #Фазовые переходы
    #Phase transitions, #Фазові
    переходи
    t.me/scilib_yura15cbx/538

    Пиротехника, Піротехніка, Pyrotechnics
    #Пиротехника, #Піротехніка, #Pyrotechnics
    t.me/scilib_yura15cbx/537

    Астрономия, Астрономія, Astronomy
    #Астрономия, #Астрономія, #Astronomy
    t.me/scilib_yura15cbx/536

    PPop Popular-level
    Популярная физика
    Популярна Фізика
    t.me/scilib_yura15cbx/535

    PG General courses
    Общие курсы
    Загальні курси
    t.me/scilib_yura15cbx/534

    PPl Plasma Плазма
    Физика плазмы
    #Plasma #Плазма
    #Физика плазмы
    t.me/scilib_yura15cbx/533

    PPh Philosophy of Physics
    Философия физики,
    Філософія фізики
    t.me/scilib_yura15cbx/532

    POs Oscillations and waves
    Колебания и волны
    Коливання і хвилі
    t.me/scilib_yura15cbx/531

    PNu Nuclear Physics
    Ядерна фізика
    Ядерная физика
    #Nuclear Physics
    #Ядернафізика
    #Ядерная
    физика
    t.me/scilib_yura15cbx/530

    PNc Nonlinear chaos
    Нелинейный хаос
    Нелінійний хаос
    #Nonlinear chaos
    #Нелинейныйхаос
    #Нелінійний
    хаос
    t.me/scilib_yura15cbx/529

    PM Atomic Molecular and Optical Physics
    Атомна молекулярна та оптична Фізика
    Атомная молекулярная и оптическая физика
    t.me/scilib_yura15cbx/528

    PGrc Cosmology
    Космология
    Космологія
    #Cosmology
    #Космология
    #Космологія
    t.me/scilib_yura15cbx/527

    PGr Gravitation
    Гравитация
    Гравітація
    #Gravitation
    #Гравитация
    #Гравітація
    t.me/scilib_yura15cbx/526

    PGe Encyclopaediae physics
    Енциклопедія
    Энциклопедии
    t.me/scilib_yura15cbx/525

    PE Electromagnetism
    Електромагнетизм
    Электромагнетизм
    #Electromagnetism
    #Електромагнетизм
    #Электромагнетизм
    t.me/scilib_yura15cbx/523

    PD Dynamical systems
    Динамические системы
    Динамічна система
    t.me/scilib_yura15cbx/522

    PCh Chemical physics
    Хімічна фізика
    Химическая физика
    #Chemical physics
    #Хімічнафізика
    #Химическая
    физика
    t.me/scilib_yura15cbx/521

    PCtm Theoretical mechanics
    Теоретическая механика
    Теоретична механіка
    t.me/scilib_yura15cbx/520

    PCstr Special relativity
    Спеціальна теорія відносності
    Специальная теория относительности
    t.me/scilib_yura15cbx/519

    PCft Classical fields
    Классические поля, классическая теория поля, класична теорія поля
    t.me/scilib_yura15cbx/518

  2. #paperOfTheDay is "Comparison between large-order estimates and perturbation series in a scalar field theory with Gaussian propagator" from 1978.
    The perturbation series for small coupling in #quantumFieldTheory is usually divergent (because the theory with negative coupling describes different #physics and is not "smoothly" connected with the case of positive coupling). To obtain finite physical predictions for the positive coupling case, a #resummation is needed. In the 1970s and 1980s, the computational techniques were for the first time sufficient to reach, say, order 4 in perturbation series computed with #FeynmanDiagram s, and the question arose how to actually do the resummation in practice.
    The present paper studies a model quantum field theory, where the propagator is exp(-p^2). This is not physically accurate, but it allows to compute perturbation series to very high order (order 8 here) because the #FeynmanIntegral s are easier. Secondly, one can carry out an #instanton calculation to determine the leading large-order growth. This allows to study whether or not the series coefficients match the expected growth rate, and how to use various different methods of resummation. In particular, the instanton analysis predicts the location and algebraic exponent for the leading singularity in the Borel plane, and this can be used as an additional input: Either, compute the Borel transform directly with a shifted-gamma function to account for the singularity, or make an ansatz of the type (known singularity)x(Pade approximant) for the Borel transformed function. The numerical data shows that this gives substantially higher accuracy for the resummation. journals.aps.org/prd/abstract/

  3. #paperOfTheDay is "The Diagrammar of Quantum Magnusian" from 2026.
    The Magnusian is, morally, the logarithm of the S-matrix in #quantumFieldTheory . It has a perturbative expansion similarly to #FeynmanDiagrams , but these are not exactly the same diagrams, and they come with different combinatorial factors. The Magnus expansion has long been well understood for the case of differential equations, but the application to full quantum field theory is relatively new and so far had been rather ad-hoc, by expanding the corresponding series and explicitly matching terms. The present paper provides a systematic description of which diagrams, and with which combinatorial factors, appear in the Magnus expansion in QFT. Even for a scalar QFT, this is more complicated than ordinary Feynman diagrams, e.g. because the Magnus diagrams have directed edges (representing retarded propagators). arxiv.org/abs/2605.25473