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Nuclear Theory·nucl-th

Monday·October 17, 2022

12 papers—5 primary·7 cross-listed

All12Primary5Cross-lists7
  1. 06

    [Submitted on 13 Oct 2022] (cross-list from cond-mat.quant-gas)

    Direct observation of hydrodynamization and local prethermalization

    Yuan Le · Yicheng Zhang · Sarang Gopalakrishnan · Marcos Rigol · David S. Weiss

    Hydrodynamics accurately describes relativistic heavy-ion collision experiments well before local thermal equilibrium is established. This unexpectedly rapid onset of hydrodynamics -- which takes place on the fastest available timescale -- is called hydrodynamization. It occurs when an interacting quantum system is quenched with an energy density that is much greater than its initial energy density. During hydrodynamization, energy gets redistributed across very different energy scales. Hydrodynamization precedes local equilibration among momentum modes, which is local prethermalization to a generalized Gibbs ensemble in nearly integrable systems or local thermalization in non-integrable systems. Many theories of quantum dynamics postulate local (pre)thermalization, but the associated timescale has not been quantitatively studied. Here we use an array of 1D Bose gases to directly observe both hydrodynamization and local prethermalization. After we apply a Bragg scattering pulse, hydrodynamization is evident in the fast redistribution of energy among distant momentum modes, which occurs on timescales associated with the Bragg peak energies. Local prethermalization can be seen in the slower redistribution of occupation among nearby momentum modes. We find that the time scale for local prethermalization in our system is inversely proportional to the momenta involved. During hydrodynamization and local prethermalization, existing theories cannot quantitatively model our experiment. Exact theoretical calculations in the Tonks-Girardeau limit show qualitatively similar features.

    Comments:
    28 pages, 4 main figures, 8 extended data figures
    Subjects:
    Quantum Gases (cond-mat.quant-gas); Nuclear Theory (nucl-th); Atomic Physics (physics.atom-ph); Quantum Physics (quant-ph)
    arXiv:
    2210.07318 [pdf]
    Nature(2023)·36 citations
  2. 07

    [Submitted on 14 Oct 2022] (cross-list from hep-ph)

    Schwinger-Dyson truncations in the all-soft limit: a case study

    A. C. Aguilar🇧🇷 · M. N. Ferreira🇪🇸 · B. M. Oliveira🇧🇷 · J. Papavassiliou🇪🇸

    We study a special Schwinger-Dyson equation in the context of a pure SU(3) Yang-Mills theory, formulated in the background field method. Specifically, we consider the corresponding equation for the vertex that governs the interaction of two background gluons with a ghost-antighost pair. By virtue of the background gauge invariance, this vertex satisfies a naive Slavnov-Taylor identity, which is not deformed by the ghost sector of the theory. In the all-soft limit, where all momenta vanish, the form of this vertex may be obtained exactly from the corresponding Ward identity. This special result is subsequently reproduced at the level of the Schwinger-Dyson equation, by making extensive use of Taylor's theorem and exploiting a plethora of key relations, particular to the background field method. This information permits the determination of the error associated with two distinct truncation schemes, where the potential advantage from employing lattice data for the ghost dressing function is quantitatively assessed.

    Comments:
    29 pages, 9 figures
    Subjects:
    High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Lattice (hep-lat); High Energy Physics — Theory (hep-th); Nuclear Theory (nucl-th)
    arXiv:
    2210.07429 [pdf]
    EPJC(2022)·6 citations
  3. 08

    [Submitted on 14 Oct 2022] (cross-list from hep-ph)

    Bethe-Salpeter Bound-State Solutions: Examining Semirelativistic Approaches

    Wolfgang Lucha🇦🇹

    Within the formalism of relativistic quantum field theory an adequate framework for the description of two-particle bound states, such as, for instance, all conventional (i.e., non-exotic) mesons, is provided by the Poincaré-covariant homogeneous Bethe-Salpeter equation. In applications, however, this approach usually proves to be rather involved, whence it is not always quite easy to extract the predictions sought. In view of this, a coarse idea of the bound-state spectrum to be expected might be gained by adhering to some simplifying approximations - which constitutes an entirely legitimate first step. The reliability of the insights inferred from the arising simpler bound-state equation may be straightforwardly examined by taking into account a couple of rigorous constraints on the obtained discrete spectrum. Application of these tools is illustrated for popular potentials.

    Comments:
    8 pages, 2 figures, contributed to "XVth Quark Confinement and the Hadron Spectrum" (1 - 6 August 2022, Stavanger, Norway)
    Subjects:
    High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Theory (hep-th); Nuclear Theory (nucl-th); Quantum Physics (quant-ph)
    arXiv:
    2210.07720 [pdf]
    EPJ Web Conf.(2022)·0 citations
  4. 09

    [Submitted on 14 Oct 2022] (cross-list from hep-lat)

    Thermal Transitions in Dense Two-Colour QCD

    Dale Lawlor🇮🇪 · Simon Hands🇬🇧 · Seyong Kim🇰🇷 · Jon-Ivar Skullerud🇮🇪

    The infamous sign problem makes it impossible to probe dense (baryon density ) QCD at temperatures near or below the deconfinement threshold. As a workaround, one can explore QCD-like theories such as two-colour QCD (QC2D) which don't suffer from this sign problem but are qualitively similar to real QCD. Previous studies on smaller lattice volumes have investigated deconfinement and colour superfluid to normal matter transitions. In this study we look at a larger lattice volume in an attempt to disentangle finite volume and finite temperature effects. We also fit to a larger number of diquark sources to better allow for extrapolation to zero diquark source.

    Comments:
    7 pages, 9 figures, 1 table, contributed poster presented at XVth Quark Confinement and the Hadron Spectrum conference
    Subjects:
    High Energy Physics — Lattice (hep-lat); High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
    arXiv:
    2210.07731 [pdf]
    EPJ Web Conf.(2022)·3 citations
  5. 10

    [Submitted on 14 Oct 2022] (cross-list from cond-mat.str-el)

    Addressing energy density functionals in the language of path-integrals II: Comparative study of functional renormalization group techniques applied to the (0+0)-D -symmetric -theory

    Kilian Fraboulet🇩🇪 · Jean-Paul Ebran🇫🇷

    The present paper is the second of a series of publications that aim at investigating relevant directions to turn the nuclear energy density functional (EDF) method as an effective field theory (EFT). The EDF approach has known numerous successes in nuclear theory over the past decades and is currently the only microscopic technique that can be applied to all atomic nuclei. However, the phenomenological character of the EDF method also comes with important limitations, such as the lack of an explicit connection with quantum chromodynamics (QCD). As was argued in the first paper of this series, reformulating the EDF framework as an EFT would enable us to overcome these limitations. In particular, path-integral (PI) techniques are suited to achieve such a purpose as they allow to design numerous non-perturbative approximations and can take Lagrangians possibly derived from EFTs of QCD as inputs. In our previous paper, we have illustrated such technical features for diagrammatic PI techniques in a study of the (0+0)-D -symmetric -theory. In the present work, we consider another class of PI techniques, i.e. functional renormalization group (FRG) approaches, that we apply to the same toy model. Despite our explicit interest for the nuclear many-body problem, the presented study is also directed towards FRG practitioners from various fields: technical details are provided for FRG techniques based on 1-particle-irreducible (1PI), 2-particle-irreducible (2PI) and 2-particle-point-irreducible (2PPI) effective actions (EAs), coined respectively as 1PI-, 2PI- and 2PPI-FRGs, and the treatment of the symmetry is also addressed thoroughly. Connections between these various FRG methods are identified as well.

    Comments:
    This article is part of a PhD project. The corresponding manuscript can be found at: arXiv:2210.16676
    Subjects:
    Strongly Correlated Electrons (cond-mat.str-el); Nuclear Theory (nucl-th)
    arXiv:
    2210.07748 [pdf]
    EPJA(2024)·4 citations
  6. 11

    [Submitted on 14 Oct 2022] (cross-list from hep-ph)

    Pushing forward jet substructure measurements in heavy-ion collisions

    Daniel Pablos🇮🇹 · Alba Soto-Ontoso🇫🇷

    Energetic jets that traverse the quark-gluon plasma created in heavy-ion collisions serve as excellent probes to study this new state of deconfined QCD matter. Presently, however, our ability to achieve a crisp theoretical interpretation of the crescent number of jet observables measured in experiments is hampered by the presence of selection biases. The aim of this work is to minimise those selection biases associated to the modification of the quark- vs. gluon-initiated jet fraction in order to assess the presence of other medium-induced effects, namely color decoherence, by exploring the rapidity dependence of jet substructure observables. So far, all jet substructure measurements at mid-rapidity have shown that heavy-ion jets are narrower than vacuum jets. We show both analytically and with Monte Carlo simulations that if the narrowing effect persists at forward rapidities, where the quark-initiated jet fraction is greatly increased, this could serve as an unambiguous experimental observation of color decoherence dynamics in heavy-ion collisions.

    Subjects:
    High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Experiment (hep-ex); Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
    arXiv:
    2210.07901 [pdf]
    PRD(2023)·30 citations
  7. 12

    [Submitted on 14 Oct 2022] (cross-list from hep-ph)

    Single diffractive hard exclusive processes for the study of generalized parton distributions

    Jian-Wei Qiu🇺🇸 · Zhite Yu🇺🇸

    Generalized parton distributions (GPDs) are important nonperturbative functions that provide tomographic images of partonic structures of hadrons. We introduce a type of exclusive processes, to be referred to as single diffractive hard exclusive processes (SDHEPs). We discuss the necessary and sufficient conditions for SDHEPs to be factorized into GPDs. We demonstrate that the SDHEP is not only sufficiently generic to cover all known processes for extracting GPDs, but is also well motivated for the search of new processes for the study of GPDs. We examine the sensitivity of the SDHEP to the parton momentum fraction dependence of GPDs.

    Comments:
    26 pages, 26 figures. To match the journal version
    Subjects:
    High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Experiment (hep-ex); Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
    arXiv:
    2210.07995 [pdf]
    PRD(2023)·82 citations

Affiliations

first authorsco-authorsvia INSPIRE